Human Anatomy and Hormones Quiz
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Questions and Answers

What is the primary function of testosterone?

  • Prepares the uterus for implantation
  • Promotes follicular growth
  • Inhibits ovulation
  • Stimulates sperm production and promotes sex drive (correct)

    • Which steroid is identified as the model molecule for estrogens?

  • Androstenedione
  • Testosterone
  • Progesterone
  • 17β-estradiol (correct)

    • What type of steroid hormone is progesterone classified as?

  • C17 steroid
  • C21 steroid (correct)
  • C18 steroid
  • C19 steroid

    • What triggers menstruation if fertilization does not occur?

    <p>Rapid fall of progesterone levels</p> Signup and view all the answers

    Which hormone signals the ovaries to produce more estrogen as the dominant follicle grows?

    <p>Follicle stimulating hormone (FSH)</p> Signup and view all the answers

    What is the main physiological role of estrogens?

    <p>Stimulating growth of uterus and breasts</p> Signup and view all the answers

    What type of enzymes do testes and ovaries contain that is crucial for the conversion of androgens to testosterone?

    <p>17β-hydroxysteroid dehydrogenase</p> Signup and view all the answers

    During the second half of the menstrual cycle, which hormone is primarily produced by the corpus luteum?

    <p>Progesterone</p> Signup and view all the answers

    What is the main symptom of vitamin D deficiency in adults?

    <p>Osteomalacia</p> Signup and view all the answers

    Which of the following is a prominent characteristic of rickets?

    <p>Improper mineralization of bones</p> Signup and view all the answers

    How do carotenoids contribute to human health?

    <p>Through enhancing immune system and reducing inflammation</p> Signup and view all the answers

    Which pigment is responsible for the coloration of carrots and tomatoes?

    <p>Carotenoids</p> Signup and view all the answers

    What role do carotenoids play in photosynthetic organisms?

    <p>They protect against light damage</p> Signup and view all the answers

    What is a vitamin A function associated with provitamin A carotenoids?

    <p>Supporting growth and immune function</p> Signup and view all the answers

    How do carotenoids affect cardiovascular health?

    <p>By reducing inflammation and preventing arterial blockages</p> Signup and view all the answers

    What is the primary source of vitamin D2 in the human diet?

    <p>Plant sources</p> Signup and view all the answers

    What percentage of total free cholesterol in the body is contained in the vertebrate brain?

    <p>25%</p> Signup and view all the answers

    What distinguishes carotenoids from other pigments?

    <p>Their defined chemical structure</p> Signup and view all the answers

    What is the common precursor for the synthesis of cholesterol that is mentioned?

    <p>Lanosterol</p> Signup and view all the answers

    What is the effect of phytosterols on cholesterol levels in the body?

    <p>They lower cholesterol levels.</p> Signup and view all the answers

    Which of the following statements about phytosterols is true?

    <p>They are excluded from body accumulation.</p> Signup and view all the answers

    What is the main structural difference between vitamins D2 and D3?

    <p>The source of derivation</p> Signup and view all the answers

    Which phytosterol is commonly present in all plant lipids?

    <p>Beta-sitosterol</p> Signup and view all the answers

    What biological activities do phytosterols exhibit in animals and humans?

    <p>Anti-tumor properties</p> Signup and view all the answers

    What is the primary role of cortisol in the human body?

    <p>To regulate blood glucose levels</p> Signup and view all the answers

    Which hormone is produced directly from pregnenolone?

    <p>Cortisol</p> Signup and view all the answers

    Where is aldosterone primarily produced in the body?

    <p>Zona glomerulosa of the adrenal cortex</p> Signup and view all the answers

    What type of steroid is testosterone classified as?

    <p>Androgen</p> Signup and view all the answers

    Cholesterol is primarily found in significant quantities in which of the following tissues?

    <p>Adrenal glands</p> Signup and view all the answers

    What is the classification of sterols in relation to their structure?

    <p>Triterpenes</p> Signup and view all the answers

    What role does progesterone play in the menstrual cycle?

    <p>Responsible for the luteal phase changes</p> Signup and view all the answers

    Which of the following sterols is primarily produced in the ovary?

    <p>Estradiol</p> Signup and view all the answers

    What is the biologically active form of vitamin D?

    <p>1,25-dihydroxy vitamin D3</p> Signup and view all the answers

    Which vitamin D form is synthesized in the skin upon UVB exposure?

    <p>Cholecalciferol</p> Signup and view all the answers

    What is the primary function of calcitriol in the body?

    <p>Regulating calcium and phosphorous homeostasis</p> Signup and view all the answers

    Which enzyme is responsible for hydroxylating cholecalciferol at the C-25 position in the liver?

    <p>D3-25-hydroxylase</p> Signup and view all the answers

    What role does ergosterol have in vitamin D synthesis?

    <p>It is converted to ergocalciferol when UV irradiated.</p> Signup and view all the answers

    What is the major circulating form of vitamin D in vertebrates?

    <p>25-hydroxy vitamin D3</p> Signup and view all the answers

    What factors can cause vitamin D deficiency despite its addition to milk?

    <p>Lack of UV exposure</p> Signup and view all the answers

    What happens to 25-hydroxy vitamin D3 in the kidneys?

    <p>It undergoes hydroxylation to become calcitriol.</p> Signup and view all the answers

    What are carotenoids predominantly derived from?

    <p>A 40-carbon polyene chain</p> Signup and view all the answers

    Which compound is a common xanthophyll?

    <p>Lutein</p> Signup and view all the answers

    How is vitamin A related to carotenoids?

    <p>Certain carotenoids can produce vitamin A</p> Signup and view all the answers

    Which carotenoid is particularly effective at quenching singlet oxygen?

    <p>Lycopene</p> Signup and view all the answers

    Which of the following is a source of dietary beta-carotene?

    <p>Carrots</p> Signup and view all the answers

    What role do carotenoids play in human health?

    <p>They provide provitamin A and act as antioxidants</p> Signup and view all the answers

    Which carotenoid is found in marigold petals?

    <p>Lutein</p> Signup and view all the answers

    What is the primary function of lutein and zeaxanthin in the human body?

    <p>To bolster visual acuity in the retina</p> Signup and view all the answers

    Study Notes

    Vertebrate Hormonal Steroids

    • Vertebrate hormonal steroids are divided into two major families: sexual hormones and corticosteroids. This division is primarily based on their physiological function or glandular origin.

    Sexual Hormones

    • Sexual hormones are produced in gonadal tissue (testes and ovaries).
    • The biosynthetic process includes the production of androgens like androstenedione and dehydroepiandrosterone.
    • Testes and ovaries contain 17β-hydroxysteroid dehydrogenase, which converts androgens to testosterone.

    Pathway of Sexual Hormone Synthesis

    • Cholesterol is the precursor molecule.
    • Pregnenolone is produced directly from cholesterol, which is a precursor for all C18, C19, and C21 steroids.
    • Various enzymes (e.g., 3β-hydroxysteroid dehydrogenase, 17,20 desmolase, P450c17, 17-ketoreductase, aromatase) catalyze transformations to produce other hormones (like progesterone, 17-OH pregnenolone, testosterone, estradiol, estrone, dihydrotestosterone).

    Types of Sexual Hormones

    • Estrogens: C18 steroids with a phenolic function at C-3, no methyl group at C-10, and an oxygenated function at C-17. 17β-estradiol is the model estrogen.
    • Progestagens: C21 steroids with an en-4-one-3 group and a ketone function at C-20. Progesterone is the model progestin.
    • Androgens: C19 steroids. Testosterone is the major androgen, a 17β-hydroxysteroid with an en-4-one-3 group.

    Actions of Specific Hormones

    • Testosterone: Stimulates sperm production, promotes sex drive, and develops male secondary sexual characteristics.
    • Estrogen (mostly Estradiol): Promotes follicular growth, develops female secondary sexual characteristics, stimulates growth of uterus and breasts, and promotes epiphyseal plate closure.
    • Progesterone: Prepares the uterus for implantation and gestation, and supports breast development.

    Relationships Between Hormones and the Menstrual Cycle

    • Estrogen peaks right before ovulation.
    • Progesterone is produced by the corpus luteum in the second half of the cycle and remains elevated during pregnancy.
    • Fertilization prevents further ovulation; progesterone falls to low levels if fertilization does not occur, leading to menstruation.
    • Hormones in the pituitary gland, specifically follicle-stimulating hormone (FSH), stimulate ovarian follicle development and estrogen production just prior to ovulation. Luteinizing hormone (LH) triggers ovulation.

    Steroids of the Adrenal Cortex

    • The adrenal cortex produces glucocorticoids, mineralocorticoids, and androgens.
    • Glucocorticoids regulate carbohydrate metabolism.
    • Mineralocorticoids regulate sodium and potassium levels.
    • Androgens have actions similar to those produced by the male gonads.

    Adrenal Insufficiency (Addison's Disease)

    • Adrenal insufficiency is known as Addison's disease.
    • Without steroid hormone replacement therapy, it can rapidly lead to death within one to two weeks.

    Structure of the Adrenal Gland and the Cortex's Regions

    • The adrenal gland has an outer cortex and an inner medulla.
    • The adrenal cortex is composed of three main tissue regions: Zona Glomerulosa, Zona Fasciculata, and Zona Reticularis.
    • Different regions produce specific steroid hormones due to varied enzymatic content.

    Corticosteroids

    • Corticosteroids are formed in the adrenal cortex, are C21 steroids, and contain three or more oxygen atoms.
    • They all have an en-4-one-3 group and an oxygenated function at C-20.
    • Cortisol is a major corticosteroid with hydroxyl groups at C-11, C-17, and C-21.
    • Aldosterone has only one hydroxyl group at C-11 and one aldehyde function at C-18.

    Actions of Corticosteroids

    • Aldosterone: Increases sodium reabsorption and potassium secretion.
    • Cortisol: Increases blood glucose by mobilizing protein and fat.
    • Androgens: Responsible for growth spurts at puberty and initiate sex drive.

    Steroid Derivatives

    • The steroid adrenal cortex contains derivatives (such as ones with a carbonyl at C-11), with similar properties to Cortisone, commonly used for asthma and inflammatory treatments.

    Pregnenolone

    • Pregnenolone is produced directly from cholesterol and is the precursor molecule for all C18, C19, and C21 steroids.

    Progesterone

    • A progestin, progesterone is produced directly from pregnenolone and secreted from the corpus luteum.
    • It's critical for the luteal phase of the menstrual cycle and in mammary gland differentiation.

    Aldosterone

    • The primary mineralocorticoid, aldosterone arises from progesterone within the zona glomerulosa of the adrenal cortex.
    • It elevates blood pressure, increases fluid volume, and enhances sodium uptake.

    Testosterone

    • An androgen, testosterone is synthesized in the testes.
    • It governs secondary male sex characteristics and is derived from progesterone.

    Estradiol

    • An estrogen, estradiol is produced within the ovaries.
    • It governs secondary female sex characteristics.

    Cortisol

    • The dominant glucocorticoid in humans, cortisol arises from progesterone in the zona fasciculata of the adrenal cortex.
    • It's crucial for stress adaptation, increases blood pressure and sodium uptake, and impacts the immune system significantly.

    Sterols

    • Sterols are a group of lipids resistant to saponification, found in substantial quantities in animal and plant tissues.
    • They could be free sterols or acylated (sterol esters), alkylated (steryl alkyl ethers), sulfated (cholesterol sulfate), or linked to glycosides (steryl glycosides, which can be acetylated).
    • Most phytosterols have 28 to 30 carbon atoms, with one or two carbon-carbon double bonds and a steroid skeleton. Several classes (e.g., campesterol, stigmasterol, β-sitosterol, ergosterol) are common in plants and fungi and are important for steroid synthesis.

    Cholesterol

    • Cholesterol (a C27 sterol) is abundant in vertebrate tissues (e.g., adrenal glands, nervous tissue, liver, gallstones).
    • The brain is the most cholesterol-rich organ, containing roughly 25% of the total free cholesterol in the body. Derivatives (e.g., cholesterol, lanosterol, desmosterol, 7-dehydrocholesterol) are important in various biological processes.

    Vitamin D

    • Vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol), though with slightly different molecular structures, serve similar functions in the body.
    • Vitamin D2 comes from plants, and vitamin D3 comes from animals (including humans).
    • Vitamin D is a steroid hormone that regulates gene expression by interacting with intracellular receptors.
    • The biologically active form is 1,25-dihydroxyvitamin D3 (calcitriol).
    • Calcitriol plays a primary role in calcium and phosphorous homeostasis.
    • Vitamin D3 synthesis occurs in the skin upon UVB exposure.
    • Provitamin D3 is converted to vitamin D3.
    • Vitamin D3 is hydroxylated in the liver [25-(OH)D3] which is then hydroxylated a second time in the kidneys to the active metabolite, 1,25(OH)2D3.

    Carotenoids

    • Carotenoids are fat-soluble pigments found in plants, algae, and photosynthetic bacteria, playing a key role in photosynthesis.
    • Some carotenoids are provitamin A, which can be converted to vitamin A, crucial for growth, immune system function, and eye health.
    • Carotenoids act as antioxidants, protecting cells and tissues against free radicals and singlet oxygen
    • Carotenoids provide coloration to many foods (e.g., carrots, peppers, tomatoes, citrus fruits) as well as certain animals (e.g., flamingos, salmon).
    • Important xanthophyll carotenoids include lutein, zeaxanthin, and astaxanthin (in seafood), that provide protection against sunburn and enhance immune system function.

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    Description

    Test your knowledge on human hormones and their functions in this quiz covering topics such as testosterone, estrogen, and vitamin D. Understand the physiological roles of different hormones and their impact on the body. Challenge yourself with questions about steriods, carotenoids, and related health aspects.

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