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Testosterone: Molecular, Physiological, and Behavioral Aspects

At a Glance

Title: Testosterone: Molecular, Physiological, and Behavioral Aspects

Total Categories: 7

Category Stats

  • Molecular Structure and Biosynthesis: 13 flashcards, 12 questions
  • Physiological Functions and Developmental Impact: 16 flashcards, 21 questions
  • Regulation, Metabolism, and Measurement: 15 flashcards, 18 questions
  • Clinical Relevance and Therapeutic Use: 10 flashcards, 15 questions
  • Behavioral and Social Endocrinology: 9 flashcards, 10 questions
  • Historical Discovery and Evolutionary Context: 8 flashcards, 8 questions
  • Population-Level Variations and Comparative Biology: 5 flashcards, 4 questions

Total Stats

  • Total Flashcards: 76
  • True/False Questions: 45
  • Multiple Choice Questions: 43
  • Total Questions: 88

Instructions

Click the button to expand the instructions for how to use the Wiki2Web Teacher studio in order to print, edit, and export data about Testosterone: Molecular, Physiological, and Behavioral Aspects

Welcome to Your Curriculum Command Center

This guide will turn you into a Wiki2web Studio power user. Let's unlock the features designed to give you back your weekends.

The Core Concept: What is a "Kit"?

Think of a Kit as your all-in-one digital lesson plan. It's a single, portable file that contains every piece of content for a topic: your subject categories, a central image, all your flashcards, and all your questions. The true power of the Studio is speed—once a kit is made (or you import one), you are just minutes away from printing an entire set of coursework.

Getting Started is Simple:

  • Create New Kit: Start with a clean slate. Perfect for a brand-new lesson idea.
  • Import & Edit Existing Kit: Load a .json kit file from your computer to continue your work or to modify a kit created by a colleague.
  • Restore Session: The Studio automatically saves your progress in your browser. If you get interrupted, you can restore your unsaved work with one click.

Step 1: Laying the Foundation (The Authoring Tools)

This is where you build the core knowledge of your Kit. Use the left-side navigation panel to switch between these powerful authoring modules.

⚙️ Kit Manager: Your Kit's Identity

This is the high-level control panel for your project.

  • Kit Name: Give your Kit a clear title. This will appear on all your printed materials.
  • Master Image: Upload a custom cover image for your Kit. This is essential for giving your content a professional visual identity, and it's used as the main graphic when you export your Kit as an interactive game.
  • Topics: Create the structure for your lesson. Add topics like "Chapter 1," "Vocabulary," or "Key Formulas." All flashcards and questions will be organized under these topics.

🃏 Flashcard Author: Building the Knowledge Blocks

Flashcards are the fundamental concepts of your Kit. Create them here to define terms, list facts, or pose simple questions.

  • Click "➕ Add New Flashcard" to open the editor.
  • Fill in the term/question and the definition/answer.
  • Assign the flashcard to one of your pre-defined topics.
  • To edit or remove a flashcard, simply use the ✏️ (Edit) or ❌ (Delete) icons next to any entry in the list.

✍️ Question Author: Assessing Understanding

Create a bank of questions to test knowledge. These questions are the engine for your worksheets and exams.

  • Click "➕ Add New Question".
  • Choose a Type: True/False for quick checks or Multiple Choice for more complex assessments.
  • To edit an existing question, click the ✏️ icon. You can change the question text, options, correct answer, and explanation at any time.
  • The Explanation field is a powerful tool: the text you enter here will automatically appear on the teacher's answer key and on the Smart Study Guide, providing instant feedback.

🔗 Intelligent Mapper: The Smart Connection

This is the secret sauce of the Studio. The Mapper transforms your content from a simple list into an interconnected web of knowledge, automating the creation of amazing study guides.

  • Step 1: Select a question from the list on the left.
  • Step 2: In the right panel, click on every flashcard that contains a concept required to answer that question. They will turn green, indicating a successful link.
  • The Payoff: When you generate a Smart Study Guide, these linked flashcards will automatically appear under each question as "Related Concepts."

Step 2: The Magic (The Generator Suite)

You've built your content. Now, with a few clicks, turn it into a full suite of professional, ready-to-use materials. What used to take hours of formatting and copying-and-pasting can now be done in seconds.

🎓 Smart Study Guide Maker

Instantly create the ultimate review document. It combines your questions, the correct answers, your detailed explanations, and all the "Related Concepts" you linked in the Mapper into one cohesive, printable guide.

📝 Worksheet & 📄 Exam Builder

Generate unique assessments every time. The questions and multiple-choice options are randomized automatically. Simply select your topics, choose how many questions you need, and generate:

  • A Student Version, clean and ready for quizzing.
  • A Teacher Version, complete with a detailed answer key and the explanations you wrote.

🖨️ Flashcard Printer

Forget wrestling with table layouts in a word processor. Select a topic, choose a cards-per-page layout, and instantly generate perfectly formatted, print-ready flashcard sheets.

Step 3: Saving and Collaborating

  • 💾 Export & Save Kit: This is your primary save function. It downloads the entire Kit (content, images, and all) to your computer as a single .json file. Use this to create permanent backups and share your work with others.
  • ➕ Import & Merge Kit: Combine your work. You can merge a colleague's Kit into your own or combine two of your lessons into a larger review Kit.

You're now ready to reclaim your time.

You're not just a teacher; you're a curriculum designer, and this is your Studio.

This page is an interactive visualization based on the Wikipedia article "Testosterone" (opens in new tab) and its cited references.

Text content is available under the Creative Commons Attribution-ShareAlike 4.0 License (opens in new tab). Additional terms may apply.

Disclaimer: This website is for informational purposes only and does not constitute any kind of advice. The information is not a substitute for consulting official sources or records or seeking advice from qualified professionals.


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Study Guide: Testosterone: Molecular, Physiological, and Behavioral Aspects

Study Guide: Testosterone: Molecular, Physiological, and Behavioral Aspects

Molecular Structure and Biosynthesis

Testosterone is classified as a steroid hormone of the androstane class, featuring a ketone group at position three and a hydroxyl group at position seventeen.

Answer: True

Testosterone is indeed a steroid hormone belonging to the androstane class, characterized by a ketone group at position three and a hydroxyl group at position seventeen.

Related Concepts:

  • Chemically, how is testosterone classified and what are its key structural features?: Testosterone is classified as a steroid hormone of the androstane class, characterized by a ketone group at position three and a hydroxyl group at position seventeen.
  • What was the chemical identification of testosterone, and what did this discovery enable?: Testosterone was identified as 17β-hydroxyandrost-4-en-3-one (C19H28O2), a solid polycyclic alcohol with a hydroxyl group at the 17th carbon atom. This precise identification enabled further chemical modifications, such as esterification and alkylation, to synthesized testosterone.

Testosterone can only act directly on target tissues and cannot be metabolized into other active forms.

Answer: False

Testosterone can act directly on target tissues, but it can also be metabolized into other active forms, such as dihydrotestosterone (DHT) by 5α-reductase or estradiol by aromatase, which then exert their own biological effects.

Related Concepts:

  • How does testosterone exert its effects on target tissues, and what are its key active metabolites?: Testosterone can act directly on target tissues by binding to the androgen receptor, or it can be metabolized. It can be converted by 5α-reductase into dihydrotestosterone (DHT) or aromatized to estradiol (E2). Both testosterone and DHT bind to the androgen receptor, with DHT exhibiting a stronger binding affinity.
  • What are the two main mechanisms through which testosterone exerts its effects in vertebrates?: Testosterone exerts its effects in humans and other vertebrates primarily through two mechanisms: by directly activating the androgen receptor (or indirectly as dihydrotestosterone), and by being converted to estradiol and activating certain estrogen receptors.
  • What are the biologically important immediate metabolites of testosterone, and where are they formed?: Two biologically important immediate metabolites of testosterone are 5α-dihydrotestosterone (5α-DHT) and estradiol. Both can be formed in the liver and in extrahepatic tissues. Approximately 5% to 7% of testosterone is converted into 5α-DHT by 5α-reductase, and about 0.3% is converted into estradiol by aromatase.

Testosterone exerts its effects solely by directly activating the androgen receptor.

Answer: False

Testosterone exerts its effects not only by directly activating the androgen receptor (or indirectly as dihydrotestosterone) but also by being converted to estradiol and activating certain estrogen receptors.

Related Concepts:

  • What are the two main mechanisms through which testosterone exerts its effects in vertebrates?: Testosterone exerts its effects in humans and other vertebrates primarily through two mechanisms: by directly activating the androgen receptor (or indirectly as dihydrotestosterone), and by being converted to estradiol and activating certain estrogen receptors.
  • Describe the cellular mechanism of testosterone action involving the androgen receptor.: Free testosterone is transported into the cytoplasm of target tissue cells, where it can either bind directly to the androgen receptor or be converted to 5α-dihydrotestosterone (5α-DHT) by the enzyme 5α-reductase. 5α-DHT binds even more strongly to the androgen receptor than testosterone, increasing its androgenic potency. The testosterone-receptor or DHT-receptor complex then undergoes a structural change, translocates into the cell nucleus, and binds to specific nucleotide sequences on chromosomal DNA called hormone response elements (HREs), which influence the transcriptional activity of certain genes to produce androgen effects.
  • What is the primary effect of testosterone in bones and the brain, and what role does aromatization play?: In bones, the primary effect of testosterone is mediated through its aromatization to estradiol, which accelerates the ossification of cartilage into bone, leading to the closure of epiphyses and the cessation of growth. In the central nervous system, testosterone is also aromatized to estradiol, which acts as the most important feedback signal to the hypothalamus, particularly affecting LH secretion. In many mammals, prenatal or perinatal masculinization of sexually dimorphic brain areas by estradiol derived from testosterone programs later male sexual behavior.

In the cellular mechanism of testosterone action, 5α-dihydrotestosterone (5α-DHT) binds more strongly to the androgen receptor than testosterone itself.

Answer: True

5α-dihydrotestosterone (5α-DHT) binds even more strongly to the androgen receptor than testosterone, increasing its androgenic potency.

Related Concepts:

  • Describe the cellular mechanism of testosterone action involving the androgen receptor.: Free testosterone is transported into the cytoplasm of target tissue cells, where it can either bind directly to the androgen receptor or be converted to 5α-dihydrotestosterone (5α-DHT) by the enzyme 5α-reductase. 5α-DHT binds even more strongly to the androgen receptor than testosterone, increasing its androgenic potency. The testosterone-receptor or DHT-receptor complex then undergoes a structural change, translocates into the cell nucleus, and binds to specific nucleotide sequences on chromosomal DNA called hormone response elements (HREs), which influence the transcriptional activity of certain genes to produce androgen effects.
  • How does testosterone exert its effects on target tissues, and what are its key active metabolites?: Testosterone can act directly on target tissues by binding to the androgen receptor, or it can be metabolized. It can be converted by 5α-reductase into dihydrotestosterone (DHT) or aromatized to estradiol (E2). Both testosterone and DHT bind to the androgen receptor, with DHT exhibiting a stronger binding affinity.
  • Where are 5α-reductase and aromatase highly expressed, and what is the impact of 5α-DHT's potency?: 5α-reductase is highly expressed in male reproductive organs (prostate gland, seminal vesicles, epididymides), skin, hair follicles, and the brain. Aromatase is highly expressed in adipose tissue, bone, and the brain. In androgenic tissues with high 5α-reductase expression, up to 90% of testosterone is converted into 5α-DHT, which is about 5 times more potent as an androgen receptor agonist than testosterone, leading to a 2- to 3-fold potentiation of testosterone's effects in these tissues.

The primary effect of testosterone in bones is directly through its binding to the androgen receptor, not through aromatization to estradiol.

Answer: False

In bones, the primary effect of testosterone is mediated through its aromatization to estradiol, which accelerates the ossification of cartilage into bone, rather than directly through androgen receptor binding.

Related Concepts:

  • What is the primary effect of testosterone in bones and the brain, and what role does aromatization play?: In bones, the primary effect of testosterone is mediated through its aromatization to estradiol, which accelerates the ossification of cartilage into bone, leading to the closure of epiphyses and the cessation of growth. In the central nervous system, testosterone is also aromatized to estradiol, which acts as the most important feedback signal to the hypothalamus, particularly affecting LH secretion. In many mammals, prenatal or perinatal masculinization of sexually dimorphic brain areas by estradiol derived from testosterone programs later male sexual behavior.
  • What are the primary anabolic effects of testosterone?: The anabolic effects of testosterone include increasing muscle mass and strength, enhancing bone density and strength, and stimulating linear growth and bone maturation.
  • What are the two main mechanisms through which testosterone exerts its effects in vertebrates?: Testosterone exerts its effects in humans and other vertebrates primarily through two mechanisms: by directly activating the androgen receptor (or indirectly as dihydrotestosterone), and by being converted to estradiol and activating certain estrogen receptors.

The initial step in testosterone biosynthesis involves the oxidative cleavage of cholesterol's side-chain, yielding pregnenolone.

Answer: True

The initial step in testosterone biosynthesis involves the oxidative cleavage of cholesterol's side-chain by cholesterol side-chain cleavage enzyme, resulting in the production of pregnenolone.

Related Concepts:

  • What is the initial step in the biosynthesis of testosterone from cholesterol?: The initial step in testosterone biosynthesis involves the oxidative cleavage of cholesterol's side-chain by cholesterol side-chain cleavage enzyme (P450scc, CYP11A1), a mitochondrial cytochrome P450 oxidase. This process results in the loss of six carbon atoms, yielding pregnenolone.
  • Describe the subsequent steps in testosterone biosynthesis from pregnenolone.: Following pregnenolone formation, two more carbon atoms are removed by the CYP17A1 enzyme (17α-hydroxylase/17,20-lyase) in the endoplasmic reticulum, producing various C19 steroids. The 3β-hydroxyl group is then oxidized by 3β-hydroxysteroid dehydrogenase to create androstenedione. Finally, in the rate-limiting step, the C17 keto group of androstenedione is reduced by 17β-hydroxysteroid dehydrogenase to yield testosterone.
  • How is testosterone biosynthesized, and where is it primarily converted to inactive metabolites?: Testosterone is biosynthesized through a multi-step pathway originating from cholesterol. It is primarily converted into inactive metabolites within the liver.

Chemically, testosterone is classified as a steroid hormone belonging to which class?

Answer: Androstane

Testosterone is classified as a steroid hormone belonging to the androstane class.

Related Concepts:

  • Chemically, how is testosterone classified and what are its key structural features?: Testosterone is classified as a steroid hormone of the androstane class, characterized by a ketone group at position three and a hydroxyl group at position seventeen.

How does testosterone influence the brain in adults, particularly regarding LH secretion?

Answer: It is aromatized into estradiol, which acts as a crucial feedback signal to the hypothalamus affecting LH secretion.

In the central nervous system, testosterone is aromatized into estradiol, which then acts as a crucial feedback signal to the hypothalamus, particularly affecting LH secretion.

Related Concepts:

  • What is the primary effect of testosterone in bones and the brain, and what role does aromatization play?: In bones, the primary effect of testosterone is mediated through its aromatization to estradiol, which accelerates the ossification of cartilage into bone, leading to the closure of epiphyses and the cessation of growth. In the central nervous system, testosterone is also aromatized to estradiol, which acts as the most important feedback signal to the hypothalamus, particularly affecting LH secretion. In many mammals, prenatal or perinatal masculinization of sexually dimorphic brain areas by estradiol derived from testosterone programs later male sexual behavior.
  • How does testosterone influence the brain in adults, and what role does estradiol play in this process?: The brain is also subject to sexual differentiation, with the male human brain being, on average, larger. In the central nervous system, testosterone is aromatized into estradiol, which is responsible for the masculinization of the brain in male mice and serves as a crucial feedback signal to the hypothalamus, particularly affecting LH secretion. In humans, masculinization of the fetal brain appears to be associated with functional androgen receptors.

What is one of the two main mechanisms through which testosterone exerts its effects in vertebrates?

Answer: Being converted to estradiol and activating certain estrogen receptors

One of the two main mechanisms through which testosterone exerts its effects in vertebrates is by being converted to estradiol and activating certain estrogen receptors.

Related Concepts:

  • What are the two main mechanisms through which testosterone exerts its effects in vertebrates?: Testosterone exerts its effects in humans and other vertebrates primarily through two mechanisms: by directly activating the androgen receptor (or indirectly as dihydrotestosterone), and by being converted to estradiol and activating certain estrogen receptors.
  • What is the primary effect of testosterone in bones and the brain, and what role does aromatization play?: In bones, the primary effect of testosterone is mediated through its aromatization to estradiol, which accelerates the ossification of cartilage into bone, leading to the closure of epiphyses and the cessation of growth. In the central nervous system, testosterone is also aromatized to estradiol, which acts as the most important feedback signal to the hypothalamus, particularly affecting LH secretion. In many mammals, prenatal or perinatal masculinization of sexually dimorphic brain areas by estradiol derived from testosterone programs later male sexual behavior.
  • Describe the cellular mechanism of testosterone action involving the androgen receptor.: Free testosterone is transported into the cytoplasm of target tissue cells, where it can either bind directly to the androgen receptor or be converted to 5α-dihydrotestosterone (5α-DHT) by the enzyme 5α-reductase. 5α-DHT binds even more strongly to the androgen receptor than testosterone, increasing its androgenic potency. The testosterone-receptor or DHT-receptor complex then undergoes a structural change, translocates into the cell nucleus, and binds to specific nucleotide sequences on chromosomal DNA called hormone response elements (HREs), which influence the transcriptional activity of certain genes to produce androgen effects.

In the cellular mechanism of testosterone action, what enzyme converts testosterone to 5α-dihydrotestosterone (5α-DHT)?

Answer: 5α-reductase

The enzyme 5α-reductase converts testosterone to 5α-dihydrotestosterone (5α-DHT) in the cytoplasm of target tissue cells.

Related Concepts:

  • Describe the cellular mechanism of testosterone action involving the androgen receptor.: Free testosterone is transported into the cytoplasm of target tissue cells, where it can either bind directly to the androgen receptor or be converted to 5α-dihydrotestosterone (5α-DHT) by the enzyme 5α-reductase. 5α-DHT binds even more strongly to the androgen receptor than testosterone, increasing its androgenic potency. The testosterone-receptor or DHT-receptor complex then undergoes a structural change, translocates into the cell nucleus, and binds to specific nucleotide sequences on chromosomal DNA called hormone response elements (HREs), which influence the transcriptional activity of certain genes to produce androgen effects.
  • How does testosterone exert its effects on target tissues, and what are its key active metabolites?: Testosterone can act directly on target tissues by binding to the androgen receptor, or it can be metabolized. It can be converted by 5α-reductase into dihydrotestosterone (DHT) or aromatized to estradiol (E2). Both testosterone and DHT bind to the androgen receptor, with DHT exhibiting a stronger binding affinity.
  • Where are 5α-reductase and aromatase highly expressed, and what is the impact of 5α-DHT's potency?: 5α-reductase is highly expressed in male reproductive organs (prostate gland, seminal vesicles, epididymides), skin, hair follicles, and the brain. Aromatase is highly expressed in adipose tissue, bone, and the brain. In androgenic tissues with high 5α-reductase expression, up to 90% of testosterone is converted into 5α-DHT, which is about 5 times more potent as an androgen receptor agonist than testosterone, leading to a 2- to 3-fold potentiation of testosterone's effects in these tissues.

What is the primary effect of testosterone in bones, mediated by aromatization?

Answer: Accelerating the ossification of cartilage into bone

In bones, the primary effect of testosterone is through its aromatization to estradiol, which accelerates the ossification of cartilage into bone, leading to the closure of epiphyses and the cessation of growth.

Related Concepts:

  • What is the primary effect of testosterone in bones and the brain, and what role does aromatization play?: In bones, the primary effect of testosterone is mediated through its aromatization to estradiol, which accelerates the ossification of cartilage into bone, leading to the closure of epiphyses and the cessation of growth. In the central nervous system, testosterone is also aromatized to estradiol, which acts as the most important feedback signal to the hypothalamus, particularly affecting LH secretion. In many mammals, prenatal or perinatal masculinization of sexually dimorphic brain areas by estradiol derived from testosterone programs later male sexual behavior.
  • What are the primary anabolic effects of testosterone?: The anabolic effects of testosterone include increasing muscle mass and strength, enhancing bone density and strength, and stimulating linear growth and bone maturation.

What is the initial step in the biosynthesis of testosterone from cholesterol?

Answer: Oxidative cleavage of cholesterol's side-chain to yield pregnenolone

The initial step in testosterone biosynthesis involves the oxidative cleavage of cholesterol's side-chain by cholesterol side-chain cleavage enzyme, yielding pregnenolone.

Related Concepts:

  • What is the initial step in the biosynthesis of testosterone from cholesterol?: The initial step in testosterone biosynthesis involves the oxidative cleavage of cholesterol's side-chain by cholesterol side-chain cleavage enzyme (P450scc, CYP11A1), a mitochondrial cytochrome P450 oxidase. This process results in the loss of six carbon atoms, yielding pregnenolone.
  • Describe the subsequent steps in testosterone biosynthesis from pregnenolone.: Following pregnenolone formation, two more carbon atoms are removed by the CYP17A1 enzyme (17α-hydroxylase/17,20-lyase) in the endoplasmic reticulum, producing various C19 steroids. The 3β-hydroxyl group is then oxidized by 3β-hydroxysteroid dehydrogenase to create androstenedione. Finally, in the rate-limiting step, the C17 keto group of androstenedione is reduced by 17β-hydroxysteroid dehydrogenase to yield testosterone.
  • How is testosterone biosynthesized, and where is it primarily converted to inactive metabolites?: Testosterone is biosynthesized through a multi-step pathway originating from cholesterol. It is primarily converted into inactive metabolites within the liver.

Physiological Functions and Developmental Impact

Testosterone's primary role in males is limited to the development of reproductive tissues, with no significant impact on secondary sexual characteristics.

Answer: False

Testosterone is crucial not only for the development of male reproductive tissues but also for promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair.

Related Concepts:

  • What is the primary role of testosterone in males?: Testosterone serves as the principal male sex hormone and androgen, essential for the development of male reproductive tissues (e.g., testicles, prostate) and the promotion of secondary sexual characteristics, including increased muscle and bone mass, and the growth of body hair.
  • What are the primary androgenic effects of testosterone?: Androgenic effects of testosterone encompass the maturation of sex organs, such as the penis and the formation of the scrotum in the fetus. Postnatally, typically during puberty, these effects include voice deepening and the growth of facial and underarm hair, which are characteristic male secondary sex characteristics.

In both males and females, testosterone contributes to overall health by impacting mood, cognition, metabolism, and preventing osteoporosis.

Answer: True

Testosterone plays a significant role in the overall health and well-being of both sexes, influencing mood, cognition, metabolism, and contributing to the prevention of osteoporosis.

Related Concepts:

  • Beyond male-specific functions, what broader health and well-being aspects does testosterone influence in both sexes?: In both males and females, testosterone significantly contributes to overall health and well-being, affecting mood, cognition, social and sexual behavior, metabolism, energy output, cardiovascular function, and bone density, thereby helping to prevent osteoporosis.

Anabolic effects of testosterone include increasing muscle mass and strength, enhancing bone density, and stimulating linear growth.

Answer: True

Anabolic effects of testosterone indeed include increasing muscle mass and strength, enhancing bone density and strength, and stimulating linear growth and bone maturation.

Related Concepts:

  • What are the primary anabolic effects of testosterone?: The anabolic effects of testosterone include increasing muscle mass and strength, enhancing bone density and strength, and stimulating linear growth and bone maturation.
  • What are the general physiological effects of androgens, including testosterone?: Androgens, such as testosterone, generally promote protein synthesis, which in turn stimulates the growth of tissues containing androgen receptors. These effects are broadly categorized as anabolic and androgenic, with significant functional overlap.

During the first period of gestation (4-6 weeks), dihydrotestosterone plays a more significant role than testosterone in genital virilization and prostate gland formation.

Answer: True

During the first period of gestation, dihydrotestosterone (DHT) plays a more significant role than testosterone in genital virilization, including the formation of the prostate gland and seminal vesicles.

Related Concepts:

  • What are the effects of testosterone during the first period of gestation (4-6 weeks)?: During the first period of gestation, between 4 and 6 weeks, testosterone contributes to genital virilization, including midline fusion, phallic urethra development, scrotal thinning and rugation, and phallic enlargement. Dihydrotestosterone (DHT) plays a more significant role in these developments, alongside the formation of the prostate gland and seminal vesicles.

Prenatal androgens primarily influence adult hormone levels, with minimal impact on gendered activities or spatial abilities.

Answer: False

Prenatal androgens influence interests and engagement in gendered activities and have moderate effects on spatial abilities, potentially predicting feminine or masculine behaviors more accurately than adult hormone levels.

Related Concepts:

  • How do prenatal androgen levels during the second trimester influence sex formation and behavior?: During the second trimester, androgen levels are associated with sex formation. Specifically, testosterone, along with anti-Müllerian hormone (AMH), promotes the growth of the Wolffian duct and the degeneration of the Müllerian duct, respectively. Prenatal androgens also influence interests and engagement in gendered activities and have moderate effects on spatial abilities, potentially predicting feminine or masculine behaviors more accurately than adult hormone levels.

Male infants experience a surge in testosterone levels during early infancy, which is known to be crucial for brain feminization.

Answer: False

Male infants experience a testosterone surge in early infancy, which is theorized to be involved in brain masculinization, as testosterone is aromatized into estradiol to affect the male brain, not feminization.

Related Concepts:

  • What occurs with testosterone levels in male infants during early infancy, and what is its theorized function?: In the initial weeks of life, male infants experience a transient rise in testosterone levels, which remain in a pubertal range for several months before returning to barely detectable childhood levels by 4–7 months of age. The precise function of this surge in humans is not fully understood, but it is theorized to be involved in brain masculinization, as testosterone is aromatized into estradiol, which then crosses the blood-brain barrier to affect the male brain.
  • How does testosterone influence the brain in adults, and what role does estradiol play in this process?: The brain is also subject to sexual differentiation, with the male human brain being, on average, larger. In the central nervous system, testosterone is aromatized into estradiol, which is responsible for the masculinization of the brain in male mice and serves as a crucial feedback signal to the hypothalamus, particularly affecting LH secretion. In humans, masculinization of the fetal brain appears to be associated with functional androgen receptors.

Before puberty, rising androgen levels in both boys and girls contribute to adult-type body odor, acne, and a growth spurt.

Answer: True

Rising androgen levels before puberty in both sexes lead to adult-type body odor, increased oiliness of skin and hair, acne, and a growth spurt, among other changes.

Related Concepts:

  • What are the effects of rising androgen levels before puberty in both boys and girls?: Before puberty, increasing androgen levels in both boys and girls lead to the development of adult-type body odor, increased oiliness of skin and hair, acne, pubarche (pubic hair appearance), axillary (armpit) hair, a growth spurt, accelerated bone maturation, and the emergence of facial hair.
  • What pubertal effects are observed when androgen levels are consistently higher than normal adult female levels for prolonged periods?: When androgen levels are consistently elevated above normal adult female levels for extended durations, pubertal effects can include clitoris enlargement, increased libido, more frequent clitoral engorgement, growth and remodeling of facial bones (jaw, brow, chin, nose) in conjunction with human growth hormone, completion of bone maturation and growth termination (mediated by estradiol metabolites), increased muscle strength and mass, broader shoulders, an expanding rib cage, deepening of the voice, and growth of the Adam's apple. Additionally, sebaceous glands enlarge, potentially causing acne, subcutaneous fat in the face decreases, and pubic hair extends to the thighs and umbilicus, with the development of facial hair (sideburns, beard, mustache) and increased chest, periareolar, perianal, and leg hair, alongside androgenetic alopecia (scalp hair loss).

In adults, testosterone is essential for normal sperm development and regulates the acute hypothalamic–pituitary–adrenal axis response during dominance challenges.

Answer: True

In adults, testosterone is essential for normal sperm development by activating genes in Sertoli cells and also regulates the acute hypothalamic–pituitary–adrenal axis response during dominance challenges.

Related Concepts:

  • What are the adult effects of testosterone, particularly concerning sperm development and the HPA axis?: In adults, testosterone is critical for normal sperm development, activating genes in Sertoli cells that promote spermatogonia differentiation. It also modulates the acute hypothalamic–pituitary–adrenal axis (HPA axis) response during dominance challenges. Furthermore, androgens, including testosterone, enhance muscle growth and regulate thromboxane A2 receptors on megakaryocytes and platelets, influencing platelet aggregation.

Maintaining normal testosterone levels in elderly men has been shown to improve several parameters that reduce cardiovascular disease risk.

Answer: True

Maintaining normal testosterone levels in elderly men has been shown to improve parameters such as increased lean body mass, decreased visceral fat mass, lower total cholesterol, and improved glycemic control, which are believed to reduce cardiovascular disease risk.

Related Concepts:

  • What are the conflicting views on testosterone's role in cardiovascular health, and what benefits are associated with maintaining normal levels?: Conflicting results exist regarding testosterone's importance in maintaining cardiovascular health. Nevertheless, maintaining normal testosterone levels in elderly men has been shown to improve several parameters believed to reduce cardiovascular disease risk, such as increased lean body mass, decreased visceral fat mass, lower total cholesterol, and improved glycemic control.
  • Why is testosterone sometimes considered for older men, and what is the current clinical perspective?: Testosterone levels naturally decline with age, leading to interest in its use to mitigate this deficiency, sometimes termed andropause or late-onset hypogonadism. However, the consistent benefits or harms of testosterone therapy for age-related low levels remain subjects of ongoing research and clinical debate.
  • How is testosterone deficiency linked to the immune system and chronic inflammation?: Testosterone deficiency is associated with an increased risk of metabolic syndrome, cardiovascular disease, and mortality, which are also consequences of chronic inflammation. Plasma testosterone concentration shows an inverse correlation with multiple biomarkers of inflammation, including CRP, interleukin 1 beta, interleukin 6, TNF alpha, and leukocyte count. Testosterone substitution therapy has been shown to significantly reduce inflammatory markers.

Research indicates a linear relationship between testosterone levels and cognitive function, where higher levels always lead to improved cognition.

Answer: False

Research indicates a curvilinear or quadratic relationship between testosterone levels and cognitive function, meaning both deficient and excessive androgen levels can negatively impact cognition, not a linear improvement with higher levels.

Related Concepts:

  • What cognitive functions are influenced by testosterone, and what is the nature of the relationship between testosterone levels and cognitive decline?: Testosterone influences key cognitive functions such as attention, memory, and spatial ability in humans. Preliminary evidence suggests that low testosterone levels may be a risk factor for cognitive decline and potentially for Alzheimer's type dementia. However, research indicates a curvilinear or quadratic relationship, implying that both deficient (hypo-secretion) and excessive (hyper-secretion) androgen levels can negatively impact cognition.

Testosterone deficiency is associated with an increased risk of chronic inflammation and related conditions like metabolic syndrome.

Answer: True

Testosterone deficiency is associated with an increased risk of metabolic syndrome, cardiovascular disease, and mortality, which are consequences of chronic inflammation. Plasma testosterone concentration shows an inverse correlation with multiple biomarkers of inflammation.

Related Concepts:

  • How is testosterone deficiency linked to the immune system and chronic inflammation?: Testosterone deficiency is associated with an increased risk of metabolic syndrome, cardiovascular disease, and mortality, which are also consequences of chronic inflammation. Plasma testosterone concentration shows an inverse correlation with multiple biomarkers of inflammation, including CRP, interleukin 1 beta, interleukin 6, TNF alpha, and leukocyte count. Testosterone substitution therapy has been shown to significantly reduce inflammatory markers.
  • What are some potential consequences of insufficient testosterone levels in men?: Insufficient testosterone levels in men can manifest as frailty, increased adipose fat tissue, anxiety, depression, sexual dysfunction, and bone loss.

Which of the following is NOT a primary role of testosterone in males?

Answer: Regulating female menstrual cycles

Testosterone's primary roles in males include the development of reproductive tissues, increased muscle and bone mass, and the growth of body hair. Regulating female menstrual cycles is not a male-specific function of testosterone.

Related Concepts:

  • What is the primary role of testosterone in males?: Testosterone serves as the principal male sex hormone and androgen, essential for the development of male reproductive tissues (e.g., testicles, prostate) and the promotion of secondary sexual characteristics, including increased muscle and bone mass, and the growth of body hair.
  • What are the primary androgenic effects of testosterone?: Androgenic effects of testosterone encompass the maturation of sex organs, such as the penis and the formation of the scrotum in the fetus. Postnatally, typically during puberty, these effects include voice deepening and the growth of facial and underarm hair, which are characteristic male secondary sex characteristics.
  • Beyond male-specific functions, what broader health and well-being aspects does testosterone influence in both sexes?: In both males and females, testosterone significantly contributes to overall health and well-being, affecting mood, cognition, social and sexual behavior, metabolism, energy output, cardiovascular function, and bone density, thereby helping to prevent osteoporosis.

Beyond male-specific functions, what aspect of health and well-being does testosterone contribute to in both sexes?

Answer: Preventing osteoporosis and influencing mood and cognition

In both males and females, testosterone contributes to overall health by impacting mood, cognition, metabolism, and helping to prevent osteoporosis.

Related Concepts:

  • Beyond male-specific functions, what broader health and well-being aspects does testosterone influence in both sexes?: In both males and females, testosterone significantly contributes to overall health and well-being, affecting mood, cognition, social and sexual behavior, metabolism, energy output, cardiovascular function, and bone density, thereby helping to prevent osteoporosis.

Which of the following is an anabolic effect of testosterone?

Answer: Increasing muscle mass and strength

Anabolic effects of testosterone include increasing muscle mass and strength, enhancing bone density, and stimulating linear growth.

Related Concepts:

  • What are the primary anabolic effects of testosterone?: The anabolic effects of testosterone include increasing muscle mass and strength, enhancing bone density and strength, and stimulating linear growth and bone maturation.
  • What are the general physiological effects of androgens, including testosterone?: Androgens, such as testosterone, generally promote protein synthesis, which in turn stimulates the growth of tissues containing androgen receptors. These effects are broadly categorized as anabolic and androgenic, with significant functional overlap.

During the second trimester, what role do androgens like testosterone play in sex formation?

Answer: Promoting the growth of the Wolffian duct

During the second trimester, androgens like testosterone promote the growth of the Wolffian duct, while anti-Müllerian hormone (AMH) promotes the degeneration of the Müllerian duct.

Related Concepts:

  • How do prenatal androgen levels during the second trimester influence sex formation and behavior?: During the second trimester, androgen levels are associated with sex formation. Specifically, testosterone, along with anti-Müllerian hormone (AMH), promotes the growth of the Wolffian duct and the degeneration of the Müllerian duct, respectively. Prenatal androgens also influence interests and engagement in gendered activities and have moderate effects on spatial abilities, potentially predicting feminine or masculine behaviors more accurately than adult hormone levels.
  • What are the effects of testosterone during the first period of gestation (4-6 weeks)?: During the first period of gestation, between 4 and 6 weeks, testosterone contributes to genital virilization, including midline fusion, phallic urethra development, scrotal thinning and rugation, and phallic enlargement. Dihydrotestosterone (DHT) plays a more significant role in these developments, alongside the formation of the prostate gland and seminal vesicles.

What is the theorized function of the testosterone surge observed in male infants during early infancy?

Answer: To be involved in brain masculinization

The testosterone surge observed in male infants during early infancy is theorized to be involved in brain masculinization, as testosterone is aromatized into estradiol to affect the male brain.

Related Concepts:

  • What occurs with testosterone levels in male infants during early infancy, and what is its theorized function?: In the initial weeks of life, male infants experience a transient rise in testosterone levels, which remain in a pubertal range for several months before returning to barely detectable childhood levels by 4–7 months of age. The precise function of this surge in humans is not fully understood, but it is theorized to be involved in brain masculinization, as testosterone is aromatized into estradiol, which then crosses the blood-brain barrier to affect the male brain.
  • How does testosterone influence the brain in adults, and what role does estradiol play in this process?: The brain is also subject to sexual differentiation, with the male human brain being, on average, larger. In the central nervous system, testosterone is aromatized into estradiol, which is responsible for the masculinization of the brain in male mice and serves as a crucial feedback signal to the hypothalamus, particularly affecting LH secretion. In humans, masculinization of the fetal brain appears to be associated with functional androgen receptors.

Which of the following is an effect of rising androgen levels before puberty in both boys and girls?

Answer: Adult-type body odor

Before puberty, rising androgen levels in both boys and girls lead to adult-type body odor, increased oiliness of skin and hair, acne, pubarche, axillary hair, a growth spurt, and accelerated bone maturation.

Related Concepts:

  • What are the effects of rising androgen levels before puberty in both boys and girls?: Before puberty, increasing androgen levels in both boys and girls lead to the development of adult-type body odor, increased oiliness of skin and hair, acne, pubarche (pubic hair appearance), axillary (armpit) hair, a growth spurt, accelerated bone maturation, and the emergence of facial hair.
  • What pubertal effects are observed when androgen levels are consistently higher than normal adult female levels for prolonged periods?: When androgen levels are consistently elevated above normal adult female levels for extended durations, pubertal effects can include clitoris enlargement, increased libido, more frequent clitoral engorgement, growth and remodeling of facial bones (jaw, brow, chin, nose) in conjunction with human growth hormone, completion of bone maturation and growth termination (mediated by estradiol metabolites), increased muscle strength and mass, broader shoulders, an expanding rib cage, deepening of the voice, and growth of the Adam's apple. Additionally, sebaceous glands enlarge, potentially causing acne, subcutaneous fat in the face decreases, and pubic hair extends to the thighs and umbilicus, with the development of facial hair (sideburns, beard, mustache) and increased chest, periareolar, perianal, and leg hair, alongside androgenetic alopecia (scalp hair loss).

In adults, what is one essential role of testosterone regarding sperm?

Answer: Promoting spermatogonia differentiation

In adults, testosterone is essential for normal sperm development, activating genes in Sertoli cells that promote spermatogonia differentiation.

Related Concepts:

  • What are the adult effects of testosterone, particularly concerning sperm development and the HPA axis?: In adults, testosterone is critical for normal sperm development, activating genes in Sertoli cells that promote spermatogonia differentiation. It also modulates the acute hypothalamic–pituitary–adrenal axis (HPA axis) response during dominance challenges. Furthermore, androgens, including testosterone, enhance muscle growth and regulate thromboxane A2 receptors on megakaryocytes and platelets, influencing platelet aggregation.

Which of the following is a benefit associated with maintaining normal testosterone levels in elderly men, regarding cardiovascular health?

Answer: Improved glycemic control

Maintaining normal testosterone levels in elderly men has been shown to improve several parameters that reduce cardiovascular disease risk, including improved glycemic control, increased lean body mass, and decreased visceral fat mass.

Related Concepts:

  • What are the conflicting views on testosterone's role in cardiovascular health, and what benefits are associated with maintaining normal levels?: Conflicting results exist regarding testosterone's importance in maintaining cardiovascular health. Nevertheless, maintaining normal testosterone levels in elderly men has been shown to improve several parameters believed to reduce cardiovascular disease risk, such as increased lean body mass, decreased visceral fat mass, lower total cholesterol, and improved glycemic control.

What type of relationship does research suggest exists between testosterone levels and cognitive function?

Answer: A curvilinear or quadratic relationship

Research indicates a curvilinear or quadratic relationship between testosterone levels and cognitive function, meaning both deficient and excessive androgen levels can negatively impact cognition.

Related Concepts:

  • What cognitive functions are influenced by testosterone, and what is the nature of the relationship between testosterone levels and cognitive decline?: Testosterone influences key cognitive functions such as attention, memory, and spatial ability in humans. Preliminary evidence suggests that low testosterone levels may be a risk factor for cognitive decline and potentially for Alzheimer's type dementia. However, research indicates a curvilinear or quadratic relationship, implying that both deficient (hypo-secretion) and excessive (hyper-secretion) androgen levels can negatively impact cognition.

Testosterone deficiency is inversely correlated with which of the following?

Answer: Biomarkers of inflammation

Plasma testosterone concentration shows an inverse correlation with multiple biomarkers of inflammation, including CRP, interleukin 1 beta, interleukin 6, TNF alpha, and leukocyte count.

Related Concepts:

  • How is testosterone deficiency linked to the immune system and chronic inflammation?: Testosterone deficiency is associated with an increased risk of metabolic syndrome, cardiovascular disease, and mortality, which are also consequences of chronic inflammation. Plasma testosterone concentration shows an inverse correlation with multiple biomarkers of inflammation, including CRP, interleukin 1 beta, interleukin 6, TNF alpha, and leukocyte count. Testosterone substitution therapy has been shown to significantly reduce inflammatory markers.

Regulation, Metabolism, and Measurement

Testosterone is primarily converted into inactive metabolites in the kidneys, not the liver.

Answer: False

Testosterone is primarily converted into inactive metabolites in the liver, not the kidneys.

Related Concepts:

  • How is testosterone biosynthesized, and where is it primarily converted to inactive metabolites?: Testosterone is biosynthesized through a multi-step pathway originating from cholesterol. It is primarily converted into inactive metabolites within the liver.
  • Describe the main metabolic pathways of testosterone in the liver.: Testosterone is primarily metabolized in the liver. Approximately 50% undergoes conjugation into testosterone glucuronide and, to a lesser extent, testosterone sulfate. Another 40% is metabolized into 17-ketosteroids like androsterone and etiocholanolone through the actions of 5α- and 5β-reductases, 3α-hydroxysteroid dehydrogenase, and 17β-HSD. These 17-ketosteroids are then conjugated and excreted. Additionally, testosterone can be hydroxylated and oxidized by cytochrome P450 enzymes, with 6β-hydroxylation being a major transformation.

Adult females typically have testosterone levels about seven to eight times greater than adult males.

Answer: False

Adult males typically have testosterone levels approximately seven to eight times greater than adult females, with their daily production being about 20 times higher.

Related Concepts:

  • Where is testosterone primarily secreted in humans, and how do levels differ between adult males and females?: In humans and most other vertebrates, testosterone is predominantly secreted by the testicles in males and, to a lesser extent, by the ovaries in females. Adult males typically exhibit testosterone levels approximately seven to eight times greater than adult females, with daily production being about 20 times higher due to more extensive metabolism in men.
  • What are the reported total testosterone levels in non-obese young adult men and adult women?: Total testosterone levels in non-obese European and American men aged 19 to 39 years have been reported to range from 264 to 916 ng/dL, with a mean of 630 ng/dL. In adult women, mean total testosterone levels have been reported as 32.6 ng/dL.

Free testosterone is the portion of total testosterone that is strongly bound to sex hormone-binding globulin (SHBG).

Answer: False

Free testosterone refers to the portion of total testosterone that is not bound to specific carrier proteins, whereas SHBG strongly binds testosterone, effectively inhibiting its action.

Related Concepts:

  • What is 'free testosterone' and how is it transported in the blood?: Free testosterone refers to the portion of total testosterone that is not bound to specific carrier proteins. Lipophilic hormones like testosterone are transported in water-based blood plasma by specific proteins, such as sex hormone-binding globulin (SHBG), and non-specific proteins like albumin. Only the free amount of testosterone can bind to an androgenic receptor and exert biological activity.
  • What is 'bioavailable testosterone' and how does it relate to free testosterone?: Bioavailable testosterone includes both free testosterone and the portion weakly bound to albumin. While SHBG strongly binds testosterone and effectively inhibits its action, the binding to albumin is weak and easily reversible, making both the free and albumin-bound fractions available at the tissue level for biological activity.
  • What is the plasma protein binding of testosterone, and what are the main binding proteins?: The plasma protein binding of testosterone ranges from 98.0% to 98.5%, leaving 1.5% to 2.0% as free or unbound. Testosterone is primarily bound 65% to sex hormone-binding globulin (SHBG) and 33% weakly to albumin.

Bioavailable testosterone includes both free testosterone and the portion weakly bound to albumin.

Answer: True

Bioavailable testosterone comprises both free testosterone and the fraction weakly bound to albumin, as both are considered available at the tissue level for biological activity.

Related Concepts:

  • What is 'bioavailable testosterone' and how does it relate to free testosterone?: Bioavailable testosterone includes both free testosterone and the portion weakly bound to albumin. While SHBG strongly binds testosterone and effectively inhibits its action, the binding to albumin is weak and easily reversible, making both the free and albumin-bound fractions available at the tissue level for biological activity.
  • What is 'free testosterone' and how is it transported in the blood?: Free testosterone refers to the portion of total testosterone that is not bound to specific carrier proteins. Lipophilic hormones like testosterone are transported in water-based blood plasma by specific proteins, such as sex hormone-binding globulin (SHBG), and non-specific proteins like albumin. Only the free amount of testosterone can bind to an androgenic receptor and exert biological activity.
  • How is the bioavailable concentration of testosterone typically determined?: The bioavailable concentration of testosterone is commonly determined using the Vermeulen calculation or, more precisely, the modified Vermeulen method. These methods utilize chemical equilibrium, considering testosterone's binding partners in circulation: albumin (weakly bound) and sex hormone-binding globulin (strongly bound).

In males, rising testosterone levels create a positive feedback loop, further stimulating the release of GnRH, FSH, and LH.

Answer: False

In males, rising testosterone levels create a negative feedback loop, inhibiting the release of GnRH from the hypothalamus and FSH/LH from the pituitary, rather than stimulating them.

Related Concepts:

  • How is testosterone synthesis regulated in males through the hypothalamic–pituitary–testicular axis?: In males, testosterone synthesis is regulated by the hypothalamic–pituitary–testicular axis. When testosterone levels are low, the hypothalamus releases gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These hormones, in turn, stimulate the testes to synthesize testosterone. As testosterone levels rise, they create a negative feedback loop, inhibiting the release of GnRH from the hypothalamus and FSH/LH from the pituitary.

Resistance training acutely increases testosterone levels in men, but endurance training may lead to lower levels.

Answer: True

Resistance training acutely increases testosterone levels in men, while endurance training may lead to lower testosterone levels.

Related Concepts:

  • What are the effects of different types of exercise on testosterone levels in men?: Resistance training acutely increases testosterone levels in men, though this increase can be prevented in older men by protein ingestion. Conversely, endurance training in men may lead to lower testosterone levels.

Weight loss may increase testosterone levels because fat cells synthesize aromatase, which converts testosterone into estradiol.

Answer: True

Weight loss may increase testosterone levels because fat cells synthesize aromatase, an enzyme that converts testosterone into estradiol, thereby reducing testosterone availability.

Related Concepts:

  • How do weight loss and body mass index relate to testosterone levels?: Weight loss may result in an increase in testosterone levels because fat cells synthesize aromatase, an enzyme that converts testosterone into estradiol. However, no clear association between body mass index (BMI) and testosterone levels has been consistently found.

Testosterone is primarily bound 65% to albumin and 33% to sex hormone-binding globulin (SHBG) in plasma.

Answer: False

Testosterone is primarily bound 65% to sex hormone-binding globulin (SHBG) and 33% weakly to albumin in plasma, not the other way around.

Related Concepts:

  • What is the plasma protein binding of testosterone, and what are the main binding proteins?: The plasma protein binding of testosterone ranges from 98.0% to 98.5%, leaving 1.5% to 2.0% as free or unbound. Testosterone is primarily bound 65% to sex hormone-binding globulin (SHBG) and 33% weakly to albumin.
  • What is 'bioavailable testosterone' and how does it relate to free testosterone?: Bioavailable testosterone includes both free testosterone and the portion weakly bound to albumin. While SHBG strongly binds testosterone and effectively inhibits its action, the binding to albumin is weak and easily reversible, making both the free and albumin-bound fractions available at the tissue level for biological activity.
  • What is 'free testosterone' and how is it transported in the blood?: Free testosterone refers to the portion of total testosterone that is not bound to specific carrier proteins. Lipophilic hormones like testosterone are transported in water-based blood plasma by specific proteins, such as sex hormone-binding globulin (SHBG), and non-specific proteins like albumin. Only the free amount of testosterone can bind to an androgenic receptor and exert biological activity.

The liquid chromatography/tandem mass spectrometry method is preferred for measuring testosterone due to its superior specificity and precision.

Answer: True

The liquid chromatography/tandem mass spectrometry method is preferred for measuring testosterone due to its superior specificity and precision compared to other assay techniques.

Related Concepts:

  • What are the challenges in measuring testosterone levels in blood samples, and which method is preferred?: Different assay techniques can yield varying results when measuring testosterone in blood samples. Immunofluorescence assays, for instance, show considerable variability and may overestimate concentrations due to cross-reaction with structurally similar steroids. The liquid chromatography/tandem mass spectrometry method is preferred for its superior specificity and precision.

Where is testosterone primarily converted into inactive metabolites?

Answer: Liver

Testosterone is primarily converted into inactive metabolites in the liver.

Related Concepts:

  • How is testosterone biosynthesized, and where is it primarily converted to inactive metabolites?: Testosterone is biosynthesized through a multi-step pathway originating from cholesterol. It is primarily converted into inactive metabolites within the liver.
  • Describe the main metabolic pathways of testosterone in the liver.: Testosterone is primarily metabolized in the liver. Approximately 50% undergoes conjugation into testosterone glucuronide and, to a lesser extent, testosterone sulfate. Another 40% is metabolized into 17-ketosteroids like androsterone and etiocholanolone through the actions of 5α- and 5β-reductases, 3α-hydroxysteroid dehydrogenase, and 17β-HSD. These 17-ketosteroids are then conjugated and excreted. Additionally, testosterone can be hydroxylated and oxidized by cytochrome P450 enzymes, with 6β-hydroxylation being a major transformation.
  • What are the biologically important immediate metabolites of testosterone, and where are they formed?: Two biologically important immediate metabolites of testosterone are 5α-dihydrotestosterone (5α-DHT) and estradiol. Both can be formed in the liver and in extrahepatic tissues. Approximately 5% to 7% of testosterone is converted into 5α-DHT by 5α-reductase, and about 0.3% is converted into estradiol by aromatase.

How do average adult male testosterone levels compare to adult female levels?

Answer: Adult males have approximately seven to eight times greater levels.

On average, adult males have testosterone levels approximately seven to eight times greater than adult females, and their daily production is about 20 times higher.

Related Concepts:

  • What are the reported total testosterone levels in non-obese young adult men and adult women?: Total testosterone levels in non-obese European and American men aged 19 to 39 years have been reported to range from 264 to 916 ng/dL, with a mean of 630 ng/dL. In adult women, mean total testosterone levels have been reported as 32.6 ng/dL.
  • Where is testosterone primarily secreted in humans, and how do levels differ between adult males and females?: In humans and most other vertebrates, testosterone is predominantly secreted by the testicles in males and, to a lesser extent, by the ovaries in females. Adult males typically exhibit testosterone levels approximately seven to eight times greater than adult females, with daily production being about 20 times higher due to more extensive metabolism in men.

What is 'free testosterone'?

Answer: Testosterone not bound to specific carrier proteins

Free testosterone refers to the portion of total testosterone that is not bound to specific carrier proteins, making it biologically active.

Related Concepts:

  • What is 'free testosterone' and how is it transported in the blood?: Free testosterone refers to the portion of total testosterone that is not bound to specific carrier proteins. Lipophilic hormones like testosterone are transported in water-based blood plasma by specific proteins, such as sex hormone-binding globulin (SHBG), and non-specific proteins like albumin. Only the free amount of testosterone can bind to an androgenic receptor and exert biological activity.

What does bioavailable testosterone include?

Answer: Free testosterone and the portion weakly bound to albumin

Bioavailable testosterone includes both free testosterone and the portion weakly bound to albumin, as both fractions are considered available for biological activity at the tissue level.

Related Concepts:

  • What is 'bioavailable testosterone' and how does it relate to free testosterone?: Bioavailable testosterone includes both free testosterone and the portion weakly bound to albumin. While SHBG strongly binds testosterone and effectively inhibits its action, the binding to albumin is weak and easily reversible, making both the free and albumin-bound fractions available at the tissue level for biological activity.
  • What is 'free testosterone' and how is it transported in the blood?: Free testosterone refers to the portion of total testosterone that is not bound to specific carrier proteins. Lipophilic hormones like testosterone are transported in water-based blood plasma by specific proteins, such as sex hormone-binding globulin (SHBG), and non-specific proteins like albumin. Only the free amount of testosterone can bind to an androgenic receptor and exert biological activity.
  • How is the bioavailable concentration of testosterone typically determined?: The bioavailable concentration of testosterone is commonly determined using the Vermeulen calculation or, more precisely, the modified Vermeulen method. These methods utilize chemical equilibrium, considering testosterone's binding partners in circulation: albumin (weakly bound) and sex hormone-binding globulin (strongly bound).

Which cells are responsible for testosterone production in the testes?

Answer: Leydig cells

In the testes, testosterone is produced by the Leydig cells.

Related Concepts:

  • Which cells are responsible for testosterone production in the testes, and what role do Sertoli cells play?: In the testes, testosterone is produced by the Leydig cells. The male generative glands also contain Sertoli cells, which require testosterone for spermatogenesis, the process of sperm development.

How does the hypothalamic–pituitary–testicular axis regulate testosterone synthesis when levels are low?

Answer: The hypothalamus releases GnRH, stimulating the pituitary to release FSH and LH, which then stimulate the testes.

When testosterone levels are low, the hypothalamus releases GnRH, which stimulates the pituitary gland to release FSH and LH, which in turn stimulate the testes to synthesize testosterone.

Related Concepts:

  • How is testosterone synthesis regulated in males through the hypothalamic–pituitary–testicular axis?: In males, testosterone synthesis is regulated by the hypothalamic–pituitary–testicular axis. When testosterone levels are low, the hypothalamus releases gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These hormones, in turn, stimulate the testes to synthesize testosterone. As testosterone levels rise, they create a negative feedback loop, inhibiting the release of GnRH from the hypothalamus and FSH/LH from the pituitary.

Which nutrient deficiency is mentioned as potentially leading to suboptimal plasma testosterone levels?

Answer: Vitamin A

Vitamin A deficiency is mentioned as potentially leading to suboptimal plasma testosterone levels.

Related Concepts:

  • Which nutrients are mentioned as influencing testosterone levels?: Vitamin A deficiency may lead to suboptimal plasma testosterone levels. Vitamin D supplementation (400–1000 IU/d) has been shown to raise testosterone levels. Zinc deficiency lowers testosterone, but over-supplementation has no further effect. Limited evidence suggests low-fat diets may reduce total and free testosterone levels in men.

What is the recommended minimum normal level for testosterone in men by several medical groups?

Answer: 350 ng/dL

Several professional medical groups recommend that 350 ng/dL generally be considered the minimum normal level for testosterone in men.

Related Concepts:

  • What is the recommended minimum normal level for testosterone in men by several medical groups?: Several professional medical groups recommend that 350 ng/dL generally be considered the minimum normal level for testosterone in men.
  • What are the reported total testosterone levels in non-obese young adult men and adult women?: Total testosterone levels in non-obese European and American men aged 19 to 39 years have been reported to range from 264 to 916 ng/dL, with a mean of 630 ng/dL. In adult women, mean total testosterone levels have been reported as 32.6 ng/dL.
  • What do the 2020 American College of Physicians guidelines recommend regarding testosterone treatment for age-related low testosterone?: The 2020 guidelines from the American College of Physicians recommend discussing testosterone treatment for adult men with age-related low testosterone primarily for improving sexual dysfunction. They advise annual evaluations for improvement, discontinuing treatment if no benefit is observed, and considering intramuscular treatments over transdermal options due to cost-effectiveness and similar efficacy and harm profiles. Testosterone treatment for reasons other than sexual dysfunction improvement may not be recommended.

Which method is preferred for measuring testosterone levels due to its superior specificity and precision?

Answer: Liquid chromatography/tandem mass spectrometry

The liquid chromatography/tandem mass spectrometry method is preferred for measuring testosterone levels due to its superior specificity and precision.

Related Concepts:

  • What are the challenges in measuring testosterone levels in blood samples, and which method is preferred?: Different assay techniques can yield varying results when measuring testosterone in blood samples. Immunofluorescence assays, for instance, show considerable variability and may overestimate concentrations due to cross-reaction with structurally similar steroids. The liquid chromatography/tandem mass spectrometry method is preferred for its superior specificity and precision.

Clinical Relevance and Therapeutic Use

Excessive testosterone levels in men are primarily linked to increased muscle mass and improved cardiovascular health, with no known risks.

Answer: False

Excessive testosterone levels in men are associated with potential risks such as hyperandrogenism, an elevated risk of heart failure, increased mortality in men with existing prostate cancer, and male pattern baldness, rather than solely positive outcomes.

Related Concepts:

  • What are the potential risks associated with excessive testosterone levels in men?: Excessive testosterone levels in men may be linked to hyperandrogenism, an elevated risk of heart failure, increased mortality in men with existing prostate cancer, and male pattern baldness.
  • What are the conflicting views on testosterone's role in cardiovascular health, and what benefits are associated with maintaining normal levels?: Conflicting results exist regarding testosterone's importance in maintaining cardiovascular health. Nevertheless, maintaining normal testosterone levels in elderly men has been shown to improve several parameters believed to reduce cardiovascular disease risk, such as increased lean body mass, decreased visceral fat mass, lower total cholesterol, and improved glycemic control.

Testosterone is used as a medication to treat male hypogonadism, gender dysphoria, and certain types of breast cancer.

Answer: True

Testosterone is indeed utilized as a medication for male hypogonadism, gender dysphoria, and specific types of breast cancer.

Related Concepts:

  • What are the established medical applications of testosterone?: Testosterone is utilized as a medication for treating conditions such as male hypogonadism, gender dysphoria, and specific types of breast cancer, often referred to as hormone replacement therapy (HRT) or testosterone replacement therapy (TRT).
  • What are the common and serious side effects associated with testosterone medication?: Common side effects of testosterone medication include acne, swelling, and breast enlargement in males. More serious side effects can involve liver toxicity, heart disease (though a randomized trial found no evidence of major adverse cardiac events compared to placebo in men with low testosterone), and behavioral changes. Women and children exposed to testosterone medication may develop virilization, and it is not recommended for use during pregnancy or breastfeeding, or for individuals with prostate cancer.

The World Anti-Doping Agency lists testosterone as a prohibited S1 Anabolic agent substance.

Answer: True

The World Anti-Doping Agency (WADA) classifies testosterone as an S1 Anabolic agent substance, which is prohibited at all times due to its performance-enhancing effects.

Related Concepts:

  • What is the World Anti-Doping Agency's classification of testosterone?: The World Anti-Doping Agency (WADA) classifies testosterone as an S1 Anabolic agent substance, which is prohibited at all times due to its performance-enhancing properties.

Testosterone consistently increases the risk of developing prostate cancer.

Answer: False

Testosterone does not appear to increase the risk of developing prostate cancer. However, in individuals who have undergone testosterone deprivation therapy, increases beyond castrate levels have been shown to accelerate the spread of existing prostate cancer.

Related Concepts:

  • What is the relationship between testosterone levels and the risk of prostate cancer?: Testosterone does not appear to increase the risk of developing prostate cancer. However, in individuals who have undergone testosterone deprivation therapy, testosterone increases beyond castrate levels have been shown to accelerate the spread of existing prostate cancer.

High androgen levels in women are exclusively associated with increased fertility and improved skin health.

Answer: False

High androgen levels in women are associated with menstrual cycle irregularities, unusual hair growth, acne, weight gain, infertility, and sometimes scalp hair loss, rather than exclusively increased fertility and improved skin health.

Related Concepts:

  • How do high androgen levels affect women, particularly those with polycystic ovary syndrome (PCOS)?: High androgen levels in women are associated with menstrual cycle irregularities, unusual hair growth, acne, weight gain, infertility, and sometimes scalp hair loss. These effects are largely observed in women with polycystic ovary syndrome (PCOS), for whom treatments like birth control pills can help mitigate the increased testosterone levels.

Testosterone substitution therapy in androgen-deficient men with autoimmune thyroiditis can decrease thyroid autoantibody titres.

Answer: True

Testosterone substitution therapy in androgen-deficient men who also have autoimmune thyroiditis has been shown to decrease thyroid autoantibody titres and increase the thyroid's secretory capacity.

Related Concepts:

  • What specific effects does testosterone substitution therapy have on men with autoimmune thyroiditis?: In androgen-deficient men who also have autoimmune thyroiditis, testosterone substitution therapy leads to a decrease in thyroid autoantibody titres and an increase in the thyroid's secretory capacity (SPINA-GT).

The 2020 American College of Physicians guidelines recommend testosterone treatment for age-related low testosterone primarily for improving sexual dysfunction.

Answer: True

The 2020 American College of Physicians guidelines support discussing testosterone treatment for adult men with age-related low testosterone primarily for improving sexual dysfunction.

Related Concepts:

  • What do the 2020 American College of Physicians guidelines recommend regarding testosterone treatment for age-related low testosterone?: The 2020 guidelines from the American College of Physicians recommend discussing testosterone treatment for adult men with age-related low testosterone primarily for improving sexual dysfunction. They advise annual evaluations for improvement, discontinuing treatment if no benefit is observed, and considering intramuscular treatments over transdermal options due to cost-effectiveness and similar efficacy and harm profiles. Testosterone treatment for reasons other than sexual dysfunction improvement may not be recommended.

Which of the following is a potential consequence of insufficient testosterone levels in men?

Answer: Bone loss

Insufficient testosterone levels in men can lead to various abnormalities, including bone loss, frailty, accumulation of adipose fat tissue, anxiety, depression, and sexual performance issues.

Related Concepts:

  • What are some potential consequences of insufficient testosterone levels in men?: Insufficient testosterone levels in men can manifest as frailty, increased adipose fat tissue, anxiety, depression, sexual dysfunction, and bone loss.

What is a potential risk associated with excessive testosterone levels in men?

Answer: Male pattern baldness

Excessive testosterone levels in men may be linked to male pattern baldness, hyperandrogenism, a higher risk of heart failure, and increased mortality in men with existing prostate cancer.

Related Concepts:

  • What are the potential risks associated with excessive testosterone levels in men?: Excessive testosterone levels in men may be linked to hyperandrogenism, an elevated risk of heart failure, increased mortality in men with existing prostate cancer, and male pattern baldness.
  • What are the common and serious side effects associated with testosterone medication?: Common side effects of testosterone medication include acne, swelling, and breast enlargement in males. More serious side effects can involve liver toxicity, heart disease (though a randomized trial found no evidence of major adverse cardiac events compared to placebo in men with low testosterone), and behavioral changes. Women and children exposed to testosterone medication may develop virilization, and it is not recommended for use during pregnancy or breastfeeding, or for individuals with prostate cancer.

For which condition is testosterone NOT typically used as a medication?

Answer: Type 2 diabetes management

Testosterone is used as a medication for male hypogonadism, gender dysphoria, and certain types of breast cancer, but not typically for Type 2 diabetes management.

Related Concepts:

  • What are the established medical applications of testosterone?: Testosterone is utilized as a medication for treating conditions such as male hypogonadism, gender dysphoria, and specific types of breast cancer, often referred to as hormone replacement therapy (HRT) or testosterone replacement therapy (TRT).
  • What are the common and serious side effects associated with testosterone medication?: Common side effects of testosterone medication include acne, swelling, and breast enlargement in males. More serious side effects can involve liver toxicity, heart disease (though a randomized trial found no evidence of major adverse cardiac events compared to placebo in men with low testosterone), and behavioral changes. Women and children exposed to testosterone medication may develop virilization, and it is not recommended for use during pregnancy or breastfeeding, or for individuals with prostate cancer.
  • Why is testosterone sometimes considered for older men, and what is the current clinical perspective?: Testosterone levels naturally decline with age, leading to interest in its use to mitigate this deficiency, sometimes termed andropause or late-onset hypogonadism. However, the consistent benefits or harms of testosterone therapy for age-related low levels remain subjects of ongoing research and clinical debate.

What is the World Anti-Doping Agency's classification of testosterone?

Answer: S1 Anabolic agent substance

The World Anti-Doping Agency (WADA) lists testosterone as an S1 Anabolic agent substance, which is prohibited at all times.

Related Concepts:

  • What is the World Anti-Doping Agency's classification of testosterone?: The World Anti-Doping Agency (WADA) classifies testosterone as an S1 Anabolic agent substance, which is prohibited at all times due to its performance-enhancing properties.

What is the relationship between testosterone and the risk of developing prostate cancer?

Answer: Testosterone does not appear to increase the risk of developing prostate cancer.

Testosterone does not appear to increase the risk of developing prostate cancer, though it can accelerate the spread of existing prostate cancer if levels rise above castrate levels.

Related Concepts:

  • What is the relationship between testosterone levels and the risk of prostate cancer?: Testosterone does not appear to increase the risk of developing prostate cancer. However, in individuals who have undergone testosterone deprivation therapy, testosterone increases beyond castrate levels have been shown to accelerate the spread of existing prostate cancer.
  • What are the potential risks associated with excessive testosterone levels in men?: Excessive testosterone levels in men may be linked to hyperandrogenism, an elevated risk of heart failure, increased mortality in men with existing prostate cancer, and male pattern baldness.

High androgen levels in women, particularly those with PCOS, are associated with which of the following?

Answer: Unusual hair growth and acne

High androgen levels in women, particularly those with PCOS, are associated with menstrual cycle irregularities, unusual hair growth (hirsutism), acne, weight gain, infertility, and sometimes scalp hair loss.

Related Concepts:

  • How do high androgen levels affect women, particularly those with polycystic ovary syndrome (PCOS)?: High androgen levels in women are associated with menstrual cycle irregularities, unusual hair growth, acne, weight gain, infertility, and sometimes scalp hair loss. These effects are largely observed in women with polycystic ovary syndrome (PCOS), for whom treatments like birth control pills can help mitigate the increased testosterone levels.

Which of the following is a common side effect of testosterone medication?

Answer: Acne

Common side effects of testosterone medication include acne, swelling, and breast enlargement in males.

Related Concepts:

  • What are the common and serious side effects associated with testosterone medication?: Common side effects of testosterone medication include acne, swelling, and breast enlargement in males. More serious side effects can involve liver toxicity, heart disease (though a randomized trial found no evidence of major adverse cardiac events compared to placebo in men with low testosterone), and behavioral changes. Women and children exposed to testosterone medication may develop virilization, and it is not recommended for use during pregnancy or breastfeeding, or for individuals with prostate cancer.

According to the 2020 American College of Physicians guidelines, for what primary reason should testosterone treatment be discussed for adult men with age-related low testosterone?

Answer: To improve sexual dysfunction

The 2020 American College of Physicians guidelines recommend discussing testosterone treatment for adult men with age-related low testosterone primarily for improving sexual dysfunction.

Related Concepts:

  • What do the 2020 American College of Physicians guidelines recommend regarding testosterone treatment for age-related low testosterone?: The 2020 guidelines from the American College of Physicians recommend discussing testosterone treatment for adult men with age-related low testosterone primarily for improving sexual dysfunction. They advise annual evaluations for improvement, discontinuing treatment if no benefit is observed, and considering intramuscular treatments over transdermal options due to cost-effectiveness and similar efficacy and harm profiles. Testosterone treatment for reasons other than sexual dysfunction improvement may not be recommended.

Behavioral and Social Endocrinology

Sexual arousal and masturbation in women lead to significant decreases in testosterone concentrations.

Answer: False

Sexual arousal and masturbation in women result in small increases in testosterone concentrations, not significant decreases.

Related Concepts:

  • What impact do sexual arousal and masturbation have on testosterone concentrations in men and women?: Sexual arousal and masturbation in women result in small increases in testosterone concentrations. In men, plasma levels of various steroids, including testosterone, significantly increase after masturbation, with testosterone levels correlating to these changes.
  • How do testosterone levels relate to sexual activity and orgasm experience in humans?: Testosterone levels in humans follow a circadian rhythm, peaking early each day, irrespective of sexual activity. In women, there may be correlations between positive orgasm experience and testosterone levels. For men, studies have shown small or inconsistent correlations between testosterone levels and orgasm experience, as well as sexual assertiveness in both sexes.

Men with lower testosterone levels are more likely to be in a relationship or married.

Answer: True

Men with lower testosterone levels are indeed more likely to be in a relationship or married, while those with higher levels are more prone to divorce or extramarital sex.

Related Concepts:

  • How do romantic relationships and marital status generally correlate with testosterone levels in men?: Falling in love has been linked to decreases in men's testosterone levels, with mixed changes reported for women. Men with lower testosterone are more likely to be in a relationship or married, while those with higher levels are more prone to divorce or extramarital sex. Marriage or commitment may lead to decreased testosterone, and single men with prior relationship experience tend to have higher testosterone than those without, suggesting a more competitive state.

Fatherhood is associated with increased testosterone levels, promoting more competitive behaviors.

Answer: False

Fatherhood is associated with decreased testosterone levels in men, suggesting that emotions and behaviors related to paternal care reduce these hormone levels, rather than promoting competitive behaviors.

Related Concepts:

  • How does fatherhood influence testosterone levels and paternal care behaviors?: Fatherhood is associated with decreased testosterone levels in men, suggesting that emotions and behaviors related to paternal care reduce these hormone levels. Higher direct child care investment correlates with lower average testosterone and temporary fluctuations. A decrease in a father's testosterone levels in response to a baby's cry indicates empathy, which is linked to increased nurturing behavior and better infant outcomes.
  • How does testosterone influence aggression in competitive situations and social status seeking?: The rise in testosterone during competition predicts aggression in males, but not in females. Studies show that interacting with handguns and engaging in experimental games can increase testosterone and aggression. It is suggested that natural selection has made males more sensitive to competitive and status challenges, with testosterone playing a crucial role in aggressive behavior in these contexts. Testosterone may also promote status-seeking and social dominance rather than just physical aggression, and can amplify existing aggression towards lower-ranked individuals in a social hierarchy.

Elevated testosterone, alongside cortisol, is associated with an increased risk of impulsive and violent criminal behavior.

Answer: True

Elevated testosterone, particularly when combined with cortisol, is associated with an increased risk of impulsive and violent criminal behavior.

Related Concepts:

  • What theories explain the link between testosterone, aggression, and criminality?: Two main theories explain the link between testosterone and aggression/criminality. The 'challenge hypothesis' suggests that testosterone increases during puberty, facilitating reproductive and competitive behaviors, including aggression, in response to competition among males. The 'evolutionary neuroandrogenic (ENA) theory' proposes that testosterone and other androgens masculinize the brain to be competitive, even at personal risk, to enhance resource acquisition and mating success. This masculinization is influenced by both prenatal and adult testosterone levels, with higher prenatal testosterone (indicated by a low digit ratio) correlating with increased aggression.
  • What role do testosterone levels play in financial decisions and criminal behavior?: Testosterone levels significantly influence risk-taking in financial decisions, with higher levels in men potentially reducing the risk of unemployment. Elevated testosterone, alongside cortisol, is associated with an increased risk of impulsive and violent criminal behavior. Conversely, high testosterone in men may also increase generosity, primarily as a means to attract a potential mate.
  • How does testosterone influence aggression in competitive situations and social status seeking?: The rise in testosterone during competition predicts aggression in males, but not in females. Studies show that interacting with handguns and engaging in experimental games can increase testosterone and aggression. It is suggested that natural selection has made males more sensitive to competitive and status challenges, with testosterone playing a crucial role in aggressive behavior in these contexts. Testosterone may also promote status-seeking and social dominance rather than just physical aggression, and can amplify existing aggression towards lower-ranked individuals in a social hierarchy.

The 'challenge hypothesis' suggests that testosterone increases during puberty to facilitate reproductive and competitive behaviors, including aggression.

Answer: True

The 'challenge hypothesis' posits that testosterone increases during puberty to facilitate reproductive and competitive behaviors, including aggression, in response to competition among males.

Related Concepts:

  • What theories explain the link between testosterone, aggression, and criminality?: Two main theories explain the link between testosterone and aggression/criminality. The 'challenge hypothesis' suggests that testosterone increases during puberty, facilitating reproductive and competitive behaviors, including aggression, in response to competition among males. The 'evolutionary neuroandrogenic (ENA) theory' proposes that testosterone and other androgens masculinize the brain to be competitive, even at personal risk, to enhance resource acquisition and mating success. This masculinization is influenced by both prenatal and adult testosterone levels, with higher prenatal testosterone (indicated by a low digit ratio) correlating with increased aggression.
  • How does testosterone influence aggression in competitive situations and social status seeking?: The rise in testosterone during competition predicts aggression in males, but not in females. Studies show that interacting with handguns and engaging in experimental games can increase testosterone and aggression. It is suggested that natural selection has made males more sensitive to competitive and status challenges, with testosterone playing a crucial role in aggressive behavior in these contexts. Testosterone may also promote status-seeking and social dominance rather than just physical aggression, and can amplify existing aggression towards lower-ranked individuals in a social hierarchy.

Testosterone might encourage fair behavior in economic experiments, potentially as a strategy to ensure acceptance of offers.

Answer: True

In some behavioral experiments, artificially enhanced testosterone levels have been linked to fairer offers, potentially as a strategic maneuver to ensure acceptance and avoid earning nothing.

Related Concepts:

  • What is the unexpected correlation between testosterone and fair behavior in economic experiments?: Testosterone might encourage fair behavior. In a behavioral experiment where subjects decided the distribution of money, those with artificially enhanced testosterone levels generally made fairer offers than placebo recipients, thereby reducing the risk of rejection. However, other studies have shown men with high testosterone to be significantly less generous in an ultimatum game, suggesting a complex relationship where fairer offers might be a strategic maneuver to ensure acceptance and avoid earning nothing.
  • What role do testosterone levels play in financial decisions and criminal behavior?: Testosterone levels significantly influence risk-taking in financial decisions, with higher levels in men potentially reducing the risk of unemployment. Elevated testosterone, alongside cortisol, is associated with an increased risk of impulsive and violent criminal behavior. Conversely, high testosterone in men may also increase generosity, primarily as a means to attract a potential mate.

What impact do sexual arousal and masturbation have on testosterone concentrations in women?

Answer: Small increases

Sexual arousal and masturbation in women result in small increases in testosterone concentrations.

Related Concepts:

  • What impact do sexual arousal and masturbation have on testosterone concentrations in men and women?: Sexual arousal and masturbation in women result in small increases in testosterone concentrations. In men, plasma levels of various steroids, including testosterone, significantly increase after masturbation, with testosterone levels correlating to these changes.
  • How do testosterone levels relate to sexual activity and orgasm experience in humans?: Testosterone levels in humans follow a circadian rhythm, peaking early each day, irrespective of sexual activity. In women, there may be correlations between positive orgasm experience and testosterone levels. For men, studies have shown small or inconsistent correlations between testosterone levels and orgasm experience, as well as sexual assertiveness in both sexes.

How do romantic relationships and marital status generally correlate with testosterone levels in men?

Answer: Men with lower testosterone are more likely to be in a relationship or married.

Men with lower testosterone are more likely to be in a relationship or married, while those with higher levels are more prone to divorce or extramarital sex.

Related Concepts:

  • How do romantic relationships and marital status generally correlate with testosterone levels in men?: Falling in love has been linked to decreases in men's testosterone levels, with mixed changes reported for women. Men with lower testosterone are more likely to be in a relationship or married, while those with higher levels are more prone to divorce or extramarital sex. Marriage or commitment may lead to decreased testosterone, and single men with prior relationship experience tend to have higher testosterone than those without, suggesting a more competitive state.

What effect does fatherhood typically have on testosterone levels in men?

Answer: Decreases testosterone levels

Fatherhood is associated with decreased testosterone levels in men, suggesting that emotions and behaviors related to paternal care reduce these hormone levels.

Related Concepts:

  • How does fatherhood influence testosterone levels and paternal care behaviors?: Fatherhood is associated with decreased testosterone levels in men, suggesting that emotions and behaviors related to paternal care reduce these hormone levels. Higher direct child care investment correlates with lower average testosterone and temporary fluctuations. A decrease in a father's testosterone levels in response to a baby's cry indicates empathy, which is linked to increased nurturing behavior and better infant outcomes.

Which theory suggests that testosterone increases during puberty to facilitate reproductive and competitive behaviors, including aggression?

Answer: Challenge hypothesis

The 'challenge hypothesis' suggests that testosterone increases during puberty to facilitate reproductive and competitive behaviors, including aggression, in response to competition among males.

Related Concepts:

  • What theories explain the link between testosterone, aggression, and criminality?: Two main theories explain the link between testosterone and aggression/criminality. The 'challenge hypothesis' suggests that testosterone increases during puberty, facilitating reproductive and competitive behaviors, including aggression, in response to competition among males. The 'evolutionary neuroandrogenic (ENA) theory' proposes that testosterone and other androgens masculinize the brain to be competitive, even at personal risk, to enhance resource acquisition and mating success. This masculinization is influenced by both prenatal and adult testosterone levels, with higher prenatal testosterone (indicated by a low digit ratio) correlating with increased aggression.

Historical Discovery and Evolutionary Context

Charles-Édouard Brown-Séquard's self-injection of testicular extracts in 1889 definitively proved the existence of a 'rejuvenating elixir'.

Answer: False

While Charles-Édouard Brown-Séquard reported temporary vigor from his self-injections, his hopes for a definitive 'rejuvenating elixir' were dashed, and his work did not definitively prove its existence.

Related Concepts:

  • What was Charles-Édouard Brown-Séquard's contribution to testosterone research in the late 19th century?: In 1889, Charles-Édouard Brown-Séquard self-injected a 'rejuvenating elixir' derived from dog and guinea pig testicles, reporting a temporary restoration of vigor and well-being. Although his hopes for the compound were not fully realized and he faced ridicule, his work briefly stimulated further research into androgens.

Fred C. Koch and Lemuel McGee were the first to isolate crystalline male hormone from testicles.

Answer: False

Fred C. Koch and Lemuel McGee extracted a substance that re-masculinized castrated animals, but the Organon group in the Netherlands was the first to isolate the crystalline male hormone, which they named 'testosterone', in May 1935.

Related Concepts:

  • How did Fred C. Koch and Lemuel McGee contribute to the early isolation of testosterone?: In 1927, Fred C. Koch and his student Lemuel McGee at the University of Chicago extracted 20 mg of a substance from 40 pounds of bovine testicles. This substance, when administered to castrated roosters, pigs, and rats, successfully re-masculinized them, marking a significant step in isolating the testicular hormone.
  • Which group first isolated crystalline male hormone from testicles, and what did they name it?: The Organon group in the Netherlands was the first to isolate the crystalline male hormone from testicles in May 1935. They named it 'testosterone,' combining the stems of 'testicle' and 'sterol' with the suffix of 'ketone'.

Adolf Butenandt and Leopold Ruzicka jointly received the 1939 Nobel Prize in Chemistry for their independent partial syntheses of testosterone.

Answer: True

Adolf Butenandt and Leopold Ruzicka were indeed jointly awarded the 1939 Nobel Prize in Chemistry for their independent partial syntheses of testosterone from a cholesterol base.

Related Concepts:

  • What significant recognition did Butenandt and Ruzicka receive for their work on testosterone?: Adolf Butenandt and Leopold Ruzicka jointly received the 1939 Nobel Prize in Chemistry for their independent partial syntheses of testosterone from a cholesterol base.
  • Who determined the chemical structure of testosterone and achieved its chemical synthesis from cholesterol?: Adolf Butenandt of Schering elucidated the chemical structure of testosterone. He, along with Hanisch, achieved the chemical synthesis of testosterone from cholesterol in August 1935. Independently, Leopold Ruzicka and A. Wettstein of the Ciba group also published their synthesis of testosterone around the same time.

Testosterone and the classical nuclear androgen receptor first appeared in jawless vertebrates like lampreys.

Answer: False

Testosterone and the classical nuclear androgen receptor first appeared in gnathostomes (jawed vertebrates), while jawless vertebrates like lampreys use androstenedione as their male sex hormone.

Related Concepts:

  • In which animal groups did testosterone and the classical nuclear androgen receptor first appear?: Testosterone and the classical nuclear androgen receptor first appeared in gnathostomes, which are jawed vertebrates.
  • What is used as a male sex hormone in jawless vertebrates like lampreys, instead of testosterone?: Agnathans, or jawless vertebrates such as lampreys, do not produce testosterone; instead, they utilize androstenedione as their male sex hormone.

Who conducted early research linking testicular action to circulating blood fractions through castration and testicular transplantation in fowl?

Answer: Arnold Adolph Berthold

Arnold Adolph Berthold conducted early research linking testicular action to circulating blood fractions through his work on castration and testicular transplantation in fowl.

Related Concepts:

  • Who conducted early research linking testicular action to circulating blood fractions?: Early research linking testicular action to circulating blood fractions, now understood as androgenic hormones, was conducted by Arnold Adolph Berthold (1803–1861) through his work on castration and testicular transplantation in fowl.

Which group was the first to isolate the crystalline male hormone from testicles in May 1935 and named it 'testosterone'?

Answer: The Organon group in the Netherlands

The Organon group in the Netherlands was the first to isolate the crystalline male hormone from testicles in May 1935 and named it 'testosterone'.

Related Concepts:

  • Which group first isolated crystalline male hormone from testicles, and what did they name it?: The Organon group in the Netherlands was the first to isolate the crystalline male hormone from testicles in May 1935. They named it 'testosterone,' combining the stems of 'testicle' and 'sterol' with the suffix of 'ketone'.
  • How did Fred C. Koch and Lemuel McGee contribute to the early isolation of testosterone?: In 1927, Fred C. Koch and his student Lemuel McGee at the University of Chicago extracted 20 mg of a substance from 40 pounds of bovine testicles. This substance, when administered to castrated roosters, pigs, and rats, successfully re-masculinized them, marking a significant step in isolating the testicular hormone.
  • Who determined the chemical structure of testosterone and achieved its chemical synthesis from cholesterol?: Adolf Butenandt of Schering elucidated the chemical structure of testosterone. He, along with Hanisch, achieved the chemical synthesis of testosterone from cholesterol in August 1935. Independently, Leopold Ruzicka and A. Wettstein of the Ciba group also published their synthesis of testosterone around the same time.

Who, along with Hanisch, achieved the chemical synthesis of testosterone from cholesterol in August 1935?

Answer: Adolf Butenandt

Adolf Butenandt, along with Hanisch, achieved the chemical synthesis of testosterone from cholesterol in August 1935.

Related Concepts:

  • What significant recognition did Butenandt and Ruzicka receive for their work on testosterone?: Adolf Butenandt and Leopold Ruzicka jointly received the 1939 Nobel Prize in Chemistry for their independent partial syntheses of testosterone from a cholesterol base.
  • Who determined the chemical structure of testosterone and achieved its chemical synthesis from cholesterol?: Adolf Butenandt of Schering elucidated the chemical structure of testosterone. He, along with Hanisch, achieved the chemical synthesis of testosterone from cholesterol in August 1935. Independently, Leopold Ruzicka and A. Wettstein of the Ciba group also published their synthesis of testosterone around the same time.

In which animal groups did testosterone and the classical nuclear androgen receptor first appear?

Answer: Gnathostomes (jawed vertebrates)

Testosterone and the classical nuclear androgen receptor first appeared in gnathostomes, which are jawed vertebrates.

Related Concepts:

  • In which animal groups did testosterone and the classical nuclear androgen receptor first appear?: Testosterone and the classical nuclear androgen receptor first appeared in gnathostomes, which are jawed vertebrates.

Population-Level Variations and Comparative Biology

People from Central European nations like the Czech Republic and Slovakia have consistently shown significantly elevated testosterone levels.

Answer: False

People from Central European and Baltic nations such as the Czech Republic and Slovakia have exhibited significantly decreased testosterone levels, not elevated levels.

Related Concepts:

  • What geographical patterns have been observed in testosterone levels among men?: Testosterone levels have been found to vary significantly among men from different nations and backgrounds. People from Eurasian Steppe and Central Asian nations like Mongolia, Kyrgyzstan, and Uzbekistan have consistently shown significantly elevated testosterone levels, while those from Central European and Baltic nations such as the Czech Republic, Slovakia, Latvia, and Estonia have exhibited significantly decreased levels.
  • Which region and people group have recorded the highest-ever tested testosterone levels?: The region with the highest-ever tested testosterone levels is Chita, Russia, and the people group with the highest recorded levels were the Yakuts.

The Yakuts are a people group recorded with the highest-ever tested testosterone levels.

Answer: True

The Yakuts are indeed the people group recorded with the highest-ever tested testosterone levels, found in the region of Chita, Russia.

Related Concepts:

  • Which region and people group have recorded the highest-ever tested testosterone levels?: The region with the highest-ever tested testosterone levels is Chita, Russia, and the people group with the highest recorded levels were the Yakuts.
  • What geographical patterns have been observed in testosterone levels among men?: Testosterone levels have been found to vary significantly among men from different nations and backgrounds. People from Eurasian Steppe and Central Asian nations like Mongolia, Kyrgyzstan, and Uzbekistan have consistently shown significantly elevated testosterone levels, while those from Central European and Baltic nations such as the Czech Republic, Slovakia, Latvia, and Estonia have exhibited significantly decreased levels.

Which people group has been recorded with the highest-ever tested testosterone levels?

Answer: Yakuts

The Yakuts are the people group recorded with the highest-ever tested testosterone levels, found in the region of Chita, Russia.

Related Concepts:

  • Which region and people group have recorded the highest-ever tested testosterone levels?: The region with the highest-ever tested testosterone levels is Chita, Russia, and the people group with the highest recorded levels were the Yakuts.
  • What geographical patterns have been observed in testosterone levels among men?: Testosterone levels have been found to vary significantly among men from different nations and backgrounds. People from Eurasian Steppe and Central Asian nations like Mongolia, Kyrgyzstan, and Uzbekistan have consistently shown significantly elevated testosterone levels, while those from Central European and Baltic nations such as the Czech Republic, Slovakia, Latvia, and Estonia have exhibited significantly decreased levels.

What is used as a male sex hormone in jawless vertebrates like lampreys, instead of testosterone?

Answer: Androstenedione

Agnathans, or jawless vertebrates such as lampreys, utilize androstenedione as their male sex hormone, rather than testosterone.

Related Concepts:

  • What is used as a male sex hormone in jawless vertebrates like lampreys, instead of testosterone?: Agnathans, or jawless vertebrates such as lampreys, do not produce testosterone; instead, they utilize androstenedione as their male sex hormone.

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