Physiology & Anatomy II: Posterior Pituitary Hormones
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Questions and Answers

What is the chemical nature of antidiuretic hormone (ADH)?

  • Carbohydrate-based hormone
  • Steroid hormone consisting of multiple amino acids
  • Polypeptide hormone consisting of 9 amino acids (correct)
  • Amino acid derivative hormone

    • Which of the following actions is stimulated by ADH?

  • Contraction of myoepithelial cells in the breast
  • Stimulates insulin secretion from the pancreas
  • Increases urination by decreasing water reabsorption
  • Reabsorption of water from the late distal tubules (correct)

    • Which condition is caused by a deficiency of ADH?

  • Diabetes insipidus (correct)
  • Hypernatremia
  • Water retention
  • Increased blood pressure

    • What triggers an increase in ADH secretion?

    <p>Increased extracellular fluid osmolarity</p> Signup and view all the answers

    Which hormone is primarily responsible for milk ejection during breastfeeding?

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

    Which structures synthesize ADH and oxytocin respectively?

    <p>Supraoptic nucleus and paraventricular nucleus</p> Signup and view all the answers

    What is one of the physiological actions of glucocorticoid hormones?

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

    What is the primary role of the adrenal cortex?

    <p>Regulate electrolyte balance</p> Signup and view all the answers

    What triggers the secretion of oxytocin during suckling?

    <p>Affluent fibers from the nipple</p> Signup and view all the answers

    Which part of the adrenal gland secretes mineralocorticoids?

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

    What is the primary action of glucocorticoids like cortisol on carbohydrate metabolism?

    <p>Stimulate gluconeogenesis</p> Signup and view all the answers

    Which hormone is predominantly responsible for uterine contractions during labor?

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

    What effect does cortisol have on protein metabolism?

    <p>Stimulates protein catabolism</p> Signup and view all the answers

    Which zone of the adrenal cortex is primarily responsible for secreting glucocorticoids?

    <p>Zona fasciculata</p> Signup and view all the answers

    How does the dilation of the cervix affect oxytocin levels during labor?

    <p>It increases the secretion of oxytocin</p> Signup and view all the answers

    What primarily signals the release of catecholamines from the adrenal medulla?

    <p>Physical stress or demand</p> Signup and view all the answers

    What is the primary effect of cortisol on glucose metabolism?

    <p>Stimulates gluconeogenesis</p> Signup and view all the answers

    How does cortisol affect protein metabolism?

    <p>Inhibits protein synthesis</p> Signup and view all the answers

    Which cellular components does cortisol primarily decrease?

    <p>Eosinophils and T-lymphocytes</p> Signup and view all the answers

    What is one of the anti-inflammatory effects of cortisol?

    <p>Induces lipocortin synthesis</p> Signup and view all the answers

    Cortisol plays a permissive role in the actions of which substances?

    <p>Catecholamines and glucagon</p> Signup and view all the answers

    What is the role of cortisol during periods of starvation?

    <p>Increase in glucose supply to vital organs.</p> Signup and view all the answers

    What is the effect of cortisol on bone metabolism?

    <p>Inhibits bone formation and increases resorption</p> Signup and view all the answers

    How does cortisol influence blood vessel function?

    <p>Increases the vasoconstrictor effect of norepinephrine</p> Signup and view all the answers

    Which type of regulation involves CRH and ACTH in the secretion of glucocorticoids?

    <p>Hypothalamic and anterior pituitary regulation.</p> Signup and view all the answers

    What is a diabetogenic effect of glucocorticoids?

    <p>Decrease in glucose uptake and oxidation by muscles</p> Signup and view all the answers

    What is the effect of cortisol on catecholamines?

    <p>Enhances their lipolytic effect.</p> Signup and view all the answers

    How does cortisol influence the regulation of its own secretion?

    <p>By inhibiting CRH and ACTH secretion.</p> Signup and view all the answers

    At what time are cortisol levels typically highest in individuals who sleep at night?

    <p>6-8 AM.</p> Signup and view all the answers

    What long-term consequence can result from high levels of glucocorticoids due to stress?

    <p>Potential harmful effects to health.</p> Signup and view all the answers

    What happens to blood glucose levels due to the permissive effect of cortisol?

    <p>They stabilize during stress.</p> Signup and view all the answers

    Which system is activated by most stressful stimuli alongside glucocorticoid secretion?

    <p>Sympathetic nervous system.</p> Signup and view all the answers

    Study Notes

    Physiology & Anatomy II: Posterior Pituitary & Adrenal Cortex

    • Posterior Pituitary Hormone (ADH/Vasopressin):
      • Synthesized in the supraoptic nucleus (SON), transported to the posterior pituitary for storage.
      • Chemical nature: Polypeptide hormone (9 amino acids).
      • Actions:
        • Stimulates water reabsorption in late distal tubules and collecting ducts of the kidneys (inserts aquaporins).
        • Causes constriction of vascular smooth muscles.
      • Regulation:
        • Decreased extracellular fluid volume increases ADH secretion.
        • Increased extracellular fluid osmolarity increases ADH secretion.
        • Pain, exercise, and stress increase ADH secretion.
      • Disorders:
        • Deficiency: Diabetes insipidus (excretion of large volumes of diluted urine).
        • Excess: Water retention and increased extracellular fluid volume.

    Oxytocin Hormone

    • Secreted by the paraventricular nucleus (PVN), stored in the posterior pituitary.
    • Chemical nature: Polypeptide hormone (9 amino acids).
    • Actions:
      • Breast: Stimulates milk ejection from mammary alveoli into ducts.
      • Uterus: Stimulates uterine contractions during labor (positive feedback loop).
      • Males: Contracts vas deferens and propels sperm.
    • Regulation:
      • Suckling is the major stimulus for oxytocin secretion.
      • Cervical dilation during labor also increases oxytocin secretion.

    Adrenal Gland Anatomy

    • Located in the abdominal cavity, superior to each kidney.
    • Composed of cortex and medulla.
    • Cortex: Secretes lipid-soluble steroid hormones (corticosteroids).
      • Three zones:
        • Zona glomerulosa: Secretes mineralocorticoids (e.g., aldosterone).
        • Zona fasciculata: Secretes mainly glucocorticoids (e.g., cortisol).
        • Zona reticularis: Secretes mostly androgens.
    • Medulla: Secretes water-soluble hormones (catecholamines).

    Glucocorticoid Hormones

    • Cortisol (95%): Main glucocorticoid.
    • Corticosterone (5%): Other glucocorticoid.
    • Actions:
      • Carbohydrate Metabolism: Increases blood glucose levels through gluconeogenesis (formation of glucose from non-carbohydrate sources, mainly amino acids).
      • Protein Metabolism: Inhibits protein synthesis, increases protein breakdown, principally in skeletal muscle.
      • Lipid Metabolism: Mobilizes fatty acids (FFAs) from adipose tissue into blood plasma.
      • Blood Cells: Decreases eosinophils and T-lymphocytes, and increases RBCs and platelets.
      • Anti-inflammatory: Inhibits phospholipase A2, resulting in reduced arachidonic acid production and the associated prostaglandins and leukotrienes.
      • Immune Suppression: Inhibits the production of interleukin-2 (IL-2) and T-lymphocytes.
      • Bone: Inhibits bone formation and increases bone resorption.
    • Permissive Action: Small amounts of glucocorticoids are needed for other hormones to function properly.
      • Necessary for glucagon and catecholamines for their effects on glucose and FFA mobilization.
    • Stress Response: Essential for the body's response to stress. Increases blood glucose and promotes the conversion of lipids to FFAs for energy.

    Regulation of Glucocorticoid Secretion

    • This is a complex, regulated process involving the hypothalamus, anterior pituitary, and the adrenal cortex.
    • Hypothalamic Regulation: Stressful stimuli trigger the release of CRH (corticotropin-releasing hormone) from the hypothalamus.
    • Anterior Pituitary Regulation: CRH stimulates the release of ACTH (adrenocorticotropic hormone) from the anterior pituitary.
    • Negative Feedback Regulation: Cortisol acts on the hypothalamus and anterior pituitary to inhibit the release of CRH and ACTH, maintaining homeostasis.
    • Cortisol oscillates with a circadian rhythm: highest in the morning, lowest in the evening.

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    Description

    This quiz covers the key aspects of the posterior pituitary hormones, including ADH and oxytocin. Learn about their synthesis, actions, regulation, and associated disorders. Engage with the material to deepen your understanding of these vital hormones in human physiology.

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