Pituitary and Thyroid Glands Overview
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Questions and Answers

Which hormone is primarily responsible for stimulating sperm production in males?

  • Growth hormone (GH)
  • Luteinizing hormone (LH)
  • Follicle-stimulating hormone (FSH) (correct)
  • Prolactin

    • What role does luteinizing hormone (LH) play in the female reproductive system?

  • Triggers ovulation (correct)
  • Inhibits the release of progesterone
  • Stimulates the secretion of estrogens
  • Stimulates milk production

    • What is one of the functions of antidiuretic hormone (ADH)?

  • Reducing urine output (correct)
  • Decreasing blood pressure
  • Increasing urine output
  • Stimulating lactation

    • In males, luteinizing hormone (LH) stimulates which cells in the testes?

    <p>Leydig cells</p> Signup and view all the answers

    Which hormone released from the posterior pituitary enhances uterine contractions during delivery?

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

    What is the consequence of elevated levels of estrogen in females on FSH and LH secretion?

    <p>Suppression of LH and FSH secretion</p> Signup and view all the answers

    How does excessive alcohol consumption affect antidiuretic hormone (ADH) secretion?

    <p>Inhibits ADH secretion</p> Signup and view all the answers

    What does the release of gonadotropin-releasing hormone (GnRH) stimulate in the anterior pituitary?

    <p>Release of follicle-stimulating hormone (FSH)</p> Signup and view all the answers

    What is the primary effect of oxytocin in males and nonpregnant females?

    <p>Influences sexual pleasure</p> Signup and view all the answers

    What triggers the secretion of antidiuretic hormone (ADH)?

    <p>Increased blood osmotic pressure</p> Signup and view all the answers

    What stimulates the release of growth hormone from the anterior pituitary?

    <p>Growth hormone releasing hormone (GHRH)</p> Signup and view all the answers

    What effect does growth hormone have on metabolism?

    <p>It enhances fat breakdown.</p> Signup and view all the answers

    Which of the following hormones is NOT released from the anterior pituitary gland?

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

    What role does melanocyte-stimulating hormone (MSH) play in the body?

    <p>Influences pigment production in the skin</p> Signup and view all the answers

    What is the primary function of prolactin in the body?

    <p>Promoting milk production during lactation</p> Signup and view all the answers

    How does hypoglycemia affect the secretion of growth hormone?

    <p>It stimulates GHRH release.</p> Signup and view all the answers

    Which hormone acts as a major regulator of the hypothalamus for growth hormone release?

    <p>Growth hormone inhibiting hormone (GHIH)</p> Signup and view all the answers

    What is the function of adrenocorticotrophic hormone (ACTH)?

    <p>Stimulates the adrenal cortex to produce glucocorticoids</p> Signup and view all the answers

    What is the primary effect of GHIH when blood glucose levels are high?

    <p>Inhibits secretion of human growth hormone</p> Signup and view all the answers

    Which of the following factors promotes the secretion of growth hormone?

    <p>Increased activity of the sympathetic division</p> Signup and view all the answers

    How does high levels of T3 and T4 affect TRH secretion?

    <p>Inhibits TRH secretion</p> Signup and view all the answers

    What primarily stimulates the secretion of ACTH?

    <p>Corticotropin-releasing hormone</p> Signup and view all the answers

    What is the role of MSH in humans?

    <p>Increases skin pigmentation</p> Signup and view all the answers

    Which hormone promotes lactation directly after childbirth?

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

    What effect does low blood glucose have on the release of GHIH?

    <p>It inhibits release of GHIH</p> Signup and view all the answers

    How does prolactin secretion change during the menstrual cycle?

    <p>It rises just before menstruation starts</p> Signup and view all the answers

    Which of the following inhibits the release of prolactin?

    <p>Prolactin-inhibiting hormone (PIH)</p> Signup and view all the answers

    What is a consequence of hypersecretion of prolactin in females?

    <p>Absence of menstrual cycles</p> Signup and view all the answers

    What triggers the release of ACTH from corticotrophs?

    <p>Stress-related stimuli</p> Signup and view all the answers

    Which of the following is a factor that inhibits the secretion of growth hormone?

    <p>Rapid eye movement sleep</p> Signup and view all the answers

    What initiates lactation after childbirth?

    <p>Prolactin secretion</p> Signup and view all the answers

    What primarily regulates TSH secretion?

    <p>Thyrotropin-releasing hormone (TRH)</p> Signup and view all the answers

    Study Notes

    Pituitary Gland and Thyroid Gland

    • The pituitary gland (hypophysis) and hypothalamus work together to regulate many other endocrine glands.
    • The hypothalamus's influence on hormone release differs between the anterior and posterior pituitary lobes.

    Learning Outcomes

    • Students should be able to describe the pituitary gland.
    • Students should be able to describe the hormones released by the anterior and posterior pituitary gland.
    • Students should be able to describe the hormones released by the thyroid gland and its regulation.

    Anterior Pituitary Hormones

    • Growth hormone (GH): Stimulates growth and division of body cells, especially in bones and skeletal muscles; regulates metabolism in organs like the liver, intestines, and pancreas; stimulates protein synthesis, promotes fat breakdown, and increases blood glucose levels. GH release is stimulated by growth hormone releasing hormone (GHRH) and suppressed by growth hormone inhibiting hormone (GHIH).
    • Thyroid-stimulating hormone (TSH): Stimulates the synthesis and secretion of the thyroid hormones triiodothyronine (T3) and thyroxine (T4), both produced by the thyroid gland.
    • Adrenocorticotropic hormone (ACTH): Controls the production and secretion of cortisol and other glucocorticoids by the cortex of the adrenal glands.
    • Follicle-stimulating hormone (FSH): Stimulates the production of gametes (ova or spermatozoa) in both males and females. This plays a role in follicle development and estrogen production in women and sperm production in men.
    • Luteinizing hormone (LH): In females, LH triggers ovulation and stimulates the formation of the corpus luteum; this corpus luteum secretes progesterone. Estrogen and progesterone prepare the uterus for implantation and prepare the mammary glands for milk production. In males, LH stimulates cells to secrete testosterone.
    • Prolactin (PRL): Stimulates lactation, has a direct effect on the breasts immediately after childbirth. PRL release is stimulated by prolactin-releasing hormone (PRH). Conversely, it is reduced by prolactin-inhibiting hormone (PIH).
    • Melanocyte-stimulating hormone (MSH): Increases skin pigmentation in amphibians. Its exact role in humans is unclear.

    Regulation of GHRH & GHIH by Glucose

    • A major regulator of GHRH and GHIH secretion is the blood glucose level.
    • GHRH Mechanism:
      • Hypoglycemia stimulates the hypothalamus to secrete GHRH.
      • GHRH stimulates somatotrophs of the anterior pituitary to release human growth hormone.
      • Human growth hormone stimulates the secretion of insulin-like growth factors.
      • These factors speed up the breakdown of liver glycogen into glucose, increasing blood glucose levels to normal.
    • GHIH Mechanism:
      • Hyperglycemia stimulates the hypothalamus to secrete GHIH.
      • GHIH inhibits the secretion of human growth hormone by somatotrophs.
      • Low levels of growth hormone slow down the breakdown of glycogen in the liver, and glucose is released into the blood more slowly.
      • Blood glucose levels fall to normal.

    Factors Promoting Growth Hormone Secretion

    • Decreased fatty acids
    • Increased amino acids in the blood
    • Deep sleep
    • Increased activity of the sympathetic nervous system (stress or vigorous physical exercise); other hormones (glucagon, estrogens, cortisol, and insulin).

    Factors Inhibiting Growth Hormone Secretion

    • Increased levels of fatty acids
    • Decreased levels of amino acids in the blood
    • Rapid eye movement sleep
    • Emotional deprivation
    • Obesity
    • Low levels of thyroid hormones
    • Human growth hormone itself (through negative feedback)

    Posterior Pituitary Hormones

    • Oxytocin: Affects the mother's uterus and breasts during and after delivery. During labor, it enhances contractions of the uterus. After delivery, it stimulates milk ejection in response to stimuli such as a suckling infant. In males and nonpregnant females, its function isn't clear.
    • Antidiuretic hormone (ADH or vasopressin): Decreases urine output by increasing the permeability of water and collecting tubules of the nephrons in the kidneys; this increases reabsorption of water. This hormone also decreases water loss through sweating and constricts arterioles, increasing blood pressure. Secretion of ADH is regulated by blood volume and osmotic pressure.

    Other Factors Affecting Secretion

    • Pain, stress, trauma, anxiety, acetylcholine, nicotine, drugs such as morphine and tranquilizers can stimulate ADH secretion.
    • Alcohol inhibits ADH secretion, causing frequent urination.
    • Hyposecretion of ADH or nonfunctional ADH receptors causes diabetes insipidus.

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    Description

    This quiz covers the functions and hormones of the pituitary gland and thyroid gland, focusing on their roles in regulating the endocrine system. Students will learn about the anterior and posterior pituitary hormones, including growth hormone, and how these glands interact with the hypothalamus. Identify key hormones and their effects on the body through this comprehensive assessment.

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