Endocrine System: Adrenal Gland Effects Quiz
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Questions and Answers

What happens to the free cortisol level when CBG levels rise?

  • It fluctuates randomly
  • It stays the same
  • It increases
  • It drops initially (correct)

    • What is the role of bound steroids in the body?

  • They enhance cortisol production
  • They directly stimulate ACTH secretion
  • They accelerate glucocorticoid catabolism
  • They are inactive and act as a hormone reservoir (correct)

    • Where is cortisol primarily metabolized in the body?

  • Liver (correct)
  • Lungs
  • Muscle tissue
  • Kidneys

    • What makes cortisone an active glucocorticoid?

    <p>Its conversion to cortisol before exerting effects</p> Signup and view all the answers

    What is the primary function of the aldosterone-secreting mechanism?

    <p>Defense of intravascular volume</p> Signup and view all the answers

    What effect does standing and constriction of the thoracic inferior vena cava have on intrarenal arterial pressure?

    <p>Decreases intrarenal arterial pressure</p> Signup and view all the answers

    What is one of the major factors affecting Na+ excretion, apart from variations in aldosterone secretion?

    <p>ANP (Atrial Natriuretic Peptide)</p> Signup and view all the answers

    What is the effect of glucocorticoids on ACTH secretion?

    <p>Inhibit ACTH secretion</p> Signup and view all the answers

    What occurs when one rises from the supine to the standing position in terms of aldosterone secretion?

    <p>Increases aldosterone secretion</p> Signup and view all the answers

    Which organ shows a decrease in the number of eosinophils due to the effects of glucocorticoids?

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

    What can happen if patients with adrenal insufficiency receive a glucose infusion without glucocorticoids?

    <p>High fever ('glucose fever') followed by collapse and death</p> Signup and view all the answers

    What changes in the nervous system are reversed only by glucocorticoids in adrenal insufficiency?

    <p>Slower than normal β rhythm in electroencephalographic waves</p> Signup and view all the answers

    What happens to most of the cortisone formed in the liver?

    <p>It is promptly reduced and conjugated to form tetrahydrocortisone glucuronides.</p> Signup and view all the answers

    What is the major adrenal androgen mentioned in the text?

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

    What is the effect of androgens according to the text?

    <p>They promote protein anabolism and growth.</p> Signup and view all the answers

    How does aldosterone's half-life compare to cortisol?

    <p>Aldosterone has a much shorter half-life than cortisol.</p> Signup and view all the answers

    How do norepinephrine and epinephrine affect the secretion of insulin and glucagon?

    <p>Increase insulin secretion via α-adrenergic mechanisms and inhibit glucagon secretion via β-adrenergic mechanisms</p> Signup and view all the answers

    Which adrenergic receptors mediate the vasoconstriction produced by norepinephrine?

    <p>α1-receptors</p> Signup and view all the answers

    What is the physiologic function of dopamine in the circulation?

    <p>Causes renal vasodilation</p> Signup and view all the answers

    How does dopamine exert its positive inotropic effect on the heart?

    <p>By acting on β1-adrenergic receptors</p> Signup and view all the answers

    What is the enzyme responsible for converting cholesterol to pregnenolone in the mitochondria?

    <p>Pregnenolone dehydrogenase</p> Signup and view all the answers

    Which protein binds cortisol in the circulation?

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

    What is the primary mineralocorticoid secreted in roughly equal amounts to deoxycorticosterone according to the text?

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

    Which hormone activates adenylyl cyclase via Gs in adrenocortical cells?

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

    How do mineralocorticoids like aldosterone affect Na+ reabsorption?

    <p>Cause Na+ retention in extracellular fluid</p> Signup and view all the answers

    What is the mechanism of action of aldosterone in promoting sodium reabsorption?

    <p>Indirectly increases the synthesis of epithelial sodium channels (ENaCs)</p> Signup and view all the answers

    What effect does a drop in resting corticoid levels have on ACTH secretion?

    <p>Stimulates ACTH secretion</p> Signup and view all the answers

    Where does aldosterone bind to initiate its cellular action?

    <p>Cytoplasmic receptor</p> Signup and view all the answers

    What is the primary regulatory factor involved in increasing aldosterone secretion from the adrenal gland?

    <p>Renin from the kidney via angiotensin II</p> Signup and view all the answers

    Which condition selectively affects the output of aldosterone without affecting glucocorticoid secretion?

    <p>High potassium intake</p> Signup and view all the answers

    What effect does a direct rise in plasma K+ concentration have on the adrenal cortex?

    <p>Stimulatory effect</p> Signup and view all the answers

    Which factor stimulates the output of aldosterone, glucocorticoids, and sex hormones when first administered?

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

    What is the primary effect of aldosterone on Na+ reabsorption?

    <p>Increase in reabsorption from urine</p> Signup and view all the answers

    How does aldosterone affect the exchange of Na+ for K+ in the renal tubules?

    <p>Promotes exchange of Na+ for K+</p> Signup and view all the answers

    What is the mechanism by which aldosterone stimulates ENaC activity?

    <p>Stimulates ENaC insertion</p> Signup and view all the answers

    How does a drop in resting corticoid levels affect ACTH secretion?

    <p>Increases ACTH secretion</p> Signup and view all the answers

    What happens to urine acidity under the influence of aldosterone?

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

    How do mineralocorticoids like aldosterone affect ECF volume?

    <p>Increase it</p> Signup and view all the answers

    Signup and view all the answers

    Glucocorticoids inhibit ACTH secretion.

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

    Adrenal insufficiency is characterized by an inability to excrete a water load.

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

    In adrenal insufficiency, glucose infusion without glucocorticoids can lead to high fever and collapse.

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

    Glucocorticoids decrease the number of circulating eosinophils.

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

    Glucocorticoids increase the number of basophils in circulation.

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

    Adrenal insufficiency results in the possibility of water intoxication.

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

    The appearance of slower electroencephalographic waves in adrenal insufficiency is reversed only by mineralocorticoids.

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

    Neutrophils' numbers decrease due to the effects of glucocorticoids.

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

    Personality changes in adrenal insufficiency include irritability and inability to concentrate.

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

    Glucocorticoids increase ketone body formation in diabetics.

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

    Study Notes

    Stress and the Adrenal Gland

    • Stress, in biological terms, refers to any environmental change threatening the optimal steady state.
    • Stressors trigger homeostatic reactions at molecular, cellular, or systemic levels to restore balance.
    • Severe stress significantly increases Adrenocorticotropic Hormone (ACTH) secretion, crucial for survival.
    • Most stimuli inducing ACTH also activate the sympathetic nervous system, highlighting glucocorticoids’ role in vascular reactivity.
    • Long-term elevated ACTH can lead to adverse effects, including Cushing syndrome.

    Cushing Syndrome

    • Characterized by prolonged elevated plasma glucocorticoids, first described by Harvey Cushing.
    • Symptoms include protein depletion, leading to thin skin and poorly developed muscle; hair may become thin and scraggly.
    • Increased androgens cause facial hair growth and acne.
    • Body fat redistributes, resulting in thin extremities and accumulation in the abdomen, face, and upper back, leading to a “buffalo hump” appearance.
    • Notable "moon-faced" rounded appearance from facial obesity; often accompanied by significant potassium depletion and muscle weakness.
    • Approximately 85% of patients experience hypertension, potentially due to increased deoxycorticosterone or direct glucocorticoid effects.

    Glucocorticoid Functions

    • Glucocorticoids possess anti-inflammatory properties, inhibiting tissue injury responses and allergic reactions caused by histamine.
    • High circulating glucocorticoids are necessary for these anti-inflammatory effects, as low steroid doses may not replicate these benefits.

    Regulation of Glucocorticoid Secretion

    • ACTH from the anterior pituitary regulates basal and stress-induced glucocorticoid secretion, with a half-life of ~10 minutes.
    • ACTH enhances adrenal sensitivity to its subsequent doses, critical for normal adrenal function.
    • ACTH secretions follow a diurnal rhythm, peaking in the early morning, contributing to about 75% of daily cortisol production between 4:00 AM and 10:00 AM.
    • Feedback mechanism: free glucocorticoids inhibit ACTH secretion, aligning inhibition levels with cortisol concentration.

    Adrenal Gland Structure and Hormones

    • Composed of two functional parts: inner adrenal medulla (producing catecholamines) and outer adrenal cortex (producing steroid hormones).
    • Adrenal cortex secretes glucocorticoids for carbohydrate and protein metabolism, a mineralocorticoid for sodium balance, and sex hormones affecting reproductive functions.
    • Adrenal medulla consists of 90% epinephrine-secreting cells and 10% norepinephrine-secreting cells.

    Steroid Biosynthesis

    • Cholesterol serves as the precursor for all steroids, with origins from both acetate synthesis and uptake from LDL.
    • Cholesterol is converted to pregnenolone in mitochondria, and subsequent steps yield other steroid hormones.
    • ACTH enhances the synthesis of enzymes needed for glucocorticoids.

    Transport and Metabolism of Glucocorticoids

    • Cortisol is primarily bound to corticosteroid-binding globulin (CBG), produced in the liver and influenced by estrogen.
    • CBG levels vary with conditions like pregnancy, cirrhosis, and nephrosis impacting cortisol bioavailability.
    • Cortisol has a circulation half-life of 60–90 minutes; only free cortisol is physiologically active.
    • The liver is the main site for cortisol metabolism, converting it to biologically active forms.

    Drugs and Clinical Relevance

    • Cortisone is notable in medical use due to its ability to be activated into cortisol. It is not produced in substantial amounts by the adrenal glands.

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    Related Documents

    Endocrine System | Adrenal Gland PDF

    Description

    Test your knowledge on the effects of adrenal gland hormones on plasma glucose, lipid levels, ketone body formation, ACTH secretion, and the nervous system. Explore negative feedback responses and physiological changes related to adrenal insufficiency.

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