Adrenal Gland Steroid Biosynthesis
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Questions and Answers

What is the effect of glucocorticoids on plasma glucose levels?

  • They decrease plasma glucose levels.
  • They only increase plasma glucose levels in non-diabetic individuals.
  • They have no effect on plasma glucose levels.
  • They increase plasma glucose levels, especially for the brain and heart. (correct)

    • What is the effect of glucocorticoids on ketone body formation in diabetics?

  • They decrease ketone body formation.
  • They have no effect on ketone body formation.
  • They only affect ketone body formation in non-diabetic individuals.
  • They increase ketone body formation. (correct)

    • What is the effect of glucocorticoids on ACTH secretion?

  • They have no effect on ACTH secretion.
  • They stimulate ACTH secretion.
  • They inhibit ACTH secretion. (correct)
  • They only affect ACTH secretion in individuals with adrenal insufficiency.

    • What is the effect of glucocorticoids on the nervous system in adrenal insufficiency?

    <p>They reverse the appearance of electroencephalographic waves slower than the normal β rhythm.</p> Signup and view all the answers

    What is the effect of glucocorticoids on water metabolism in adrenal insufficiency?

    <p>They repair the ability to excrete a water load.</p> Signup and view all the answers

    What is the effect of glucocorticoids on the number of circulating eosinophils?

    <p>They decrease the number of circulating eosinophils.</p> Signup and view all the answers

    What is the main fate of 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 main difference between aldosterone and cortisol in terms of protein binding?

    <p>Aldosterone is bound to protein to a lesser extent than cortisol</p> Signup and view all the answers

    What is the main derivative of aldosterone formed in the liver?

    <p>18-glucuronide</p> Signup and view all the answers

    What is the primary adrenal androgen secreted?

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

    What percentage of urinary ketosteroids in men come from the adrenal or cortisol metabolism in the liver?

    <p>Two-thirds</p> Signup and view all the answers

    What is the primary effect of androgens?

    <p>Masculinizing effects and protein anabolism</p> Signup and view all the answers

    What is the main function of cholesterol ester hydrolase in steroid biosynthesis?

    <p>To form free cholesterol from cholesterol ester</p> Signup and view all the answers

    What is the effect of ACTH binding to adrenocortical cells?

    <p>Prompt increase in the formation of pregnenolone and its derivatives</p> Signup and view all the answers

    What is the primary function of the sterol carrier protein?

    <p>To transport cholesterol to the mitochondria</p> Signup and view all the answers

    What is the effect of estrogen on CBG production?

    <p>Increased production of CBG</p> Signup and view all the answers

    What is the ratio of mineralocorticoid activity of deoxycorticosterone to aldosterone?

    <p>3%:100%</p> Signup and view all the answers

    What is the precursor of all steroids in the adrenal gland?

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

    What is a characteristic of the skin and subcutaneous tissues in patients with Cushing syndrome?

    <p>Thin and poorly developed</p> Signup and view all the answers

    What is the primary cause of acne and facial hair increase in patients with Cushing syndrome?

    <p>Increased secretion of adrenal androgens</p> Signup and view all the answers

    What is the characteristic redistribution of body fat in patients with Cushing syndrome?

    <p>Fat accumulation in the abdominal wall, face, and upper back</p> Signup and view all the answers

    What percentage of patients with Cushing syndrome are hypertensive?

    <p>85%</p> Signup and view all the answers

    What is the effect of glucocorticoids on the inflammatory response to tissue injury?

    <p>They inhibit the inflammatory response</p> Signup and view all the answers

    What is the effect of glucocorticoids on manifestations of allergic disease?

    <p>They suppress the manifestations of allergic disease</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 happens to aldosterone secretion when one rises from the supine to the standing position?

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

    What is a factor that affects Na+ excretion, aside from aldosterone secretion?

    <p>Glomerular filtration rate</p> Signup and view all the answers

    What stimulates adrenocortical secretion and affects primarily the secretion of aldosterone in small doses?

    <p>Injections of angiotensin II</p> Signup and view all the answers

    What is increased before any consistent decrease in blood pressure takes place due to dietary sodium restriction?

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

    What happens to Na+ excretion when one rises from the supine to the standing position?

    <p>It decreases</p> Signup and view all the answers

    What is the primary consequence of increased plasma glucose levels in vital organs during adrenal insufficiency?

    <p>Improved glucose uptake in the brain and heart</p> Signup and view all the answers

    Which of the following is a characteristic of glucocorticoid deficiency in the nervous system?

    <p>Appearance of electroencephalographic waves slower than the normal β rhythm</p> Signup and view all the answers

    What is the consequence of glucocorticoid deficiency in water metabolism?

    <p>Increased risk of water intoxication</p> Signup and view all the answers

    What is the effect of glucocorticoids on the circulation of blood cells?

    <p>Increase in circulating neutrophils, platelets, and red blood cells</p> Signup and view all the answers

    What is the consequence of glucose infusion in patients with adrenal insufficiency who have not received glucocorticoids?

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

    What is the primary effect of glucocorticoids on the pituitary?

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

    What is the primary reason for the characteristic 'buffalo hump' appearance in patients with Cushing syndrome?

    <p>Redistribution of body fat in the abdominal wall, face, and upper back</p> Signup and view all the answers

    What is the primary mechanism by which glucocorticoids inhibit the inflammatory response to tissue injury?

    <p>By inhibiting the activity of inflammatory cells</p> Signup and view all the answers

    What is the primary cause of significant K+ depletion in patients with Cushing syndrome?

    <p>Salt and water retention</p> Signup and view all the answers

    What is the primary effect of increased glucocorticoid secretion on blood vessels?

    <p>Direct effect on blood vessels leading to hypertension</p> Signup and view all the answers

    What is the primary reason for the characteristic 'moon-faced' appearance in patients with Cushing syndrome?

    <p>Facial obesity due to salt and water retention</p> Signup and view all the answers

    What is the primary effect of glucocorticoids on allergic disease?

    <p>Suppression of manifestations of allergic disease</p> Signup and view all the answers

    What percentage of androgen activity do adrenal androgens have in comparison to testosterone?

    <p>Less than 20%</p> Signup and view all the answers

    What regulates secretion of adrenal androgens?

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

    What is the effect of excess adrenal androgens in adult males?

    <p>Accentuation of existing masculine characteristics</p> Signup and view all the answers

    What is androstenedione converted to in fat and other peripheral tissues?

    <p>Testosterone and estrogens</p> Signup and view all the answers

    What is the mechanism of action of glucocorticoids?

    <p>Binding to glucocorticoid receptors</p> Signup and view all the answers

    What is the effect of glucocorticoids on peripheral tissues?

    <p>Anti-insulin action</p> Signup and view all the answers

    What is the definition of stress in biology?

    <p>Any change in the environment that changes or threatens to change an existing optimal steady state</p> Signup and view all the answers

    What is the effect of increased ACTH secretion in response to stress?

    <p>It is essential for survival when the stress is severe</p> Signup and view all the answers

    What is the result of prolonged increases in plasma glucocorticoids?

    <p>Cushing syndrome</p> Signup and view all the answers

    What is the role of circulating glucocorticoids in the body's response to stress?

    <p>To maintain vascular reactivity to catecholamines</p> Signup and view all the answers

    What is a characteristic of patients with Cushing syndrome?

    <p>Protein depletion</p> Signup and view all the answers

    What is the relationship between the sympathetic nervous system and ACTH secretion?

    <p>The sympathetic nervous system stimulates ACTH secretion</p> Signup and view all the answers

    What is the effect of aldosterone on Na+ reabsorption?

    <p>It increases Na+ reabsorption from the urine and sweat.</p> Signup and view all the answers

    How does aldosterone stimulate the synthesis of ENaCs?

    <p>By increasing the insertion of ENaCs into the cell membrane from a cytoplasmic pool.</p> Signup and view all the answers

    What is the effect of chronic adrenal insufficiency on ACTH secretion?

    <p>It increases ACTH synthesis and secretion.</p> Signup and view all the answers

    What is the consequence of the exchange of Na+ for K+ and H+ in the renal tubules?

    <p>K+ diuresis and increased urine acidity.</p> Signup and view all the answers

    What is the mechanism of action of aldosterone?

    <p>It binds to a cytoplasmic receptor, and the receptor-hormone complex moves to the nucleus.</p> Signup and view all the answers

    What is the effect of aldosterone on ECF volume?

    <p>It increases ECF volume.</p> Signup and view all the answers

    Study Notes

    Adrenal Gland Steroid Biosynthesis

    • Cholesterol is the precursor of all steroids, synthesized from acetate or taken up from LDL in the circulation
    • Cholesterol ester hydrolase catalyzes the formation of free cholesterol in lipid droplets
    • Free cholesterol is transported to the mitochondria by a sterol carrier protein
    • In the mitochondria, cholesterol is converted to pregnenolone

    Adrenocortical Hormones

    • Deoxycorticosterone is a mineralocorticoid with 3% of the mineralocorticoid activity of aldosterone
    • Aldosterone is bound to protein to a slight extent and has a short half-life of about 20 minutes
    • Aldosterone is converted to tetrahydroglucuronide derivatives in the liver and kidneys
    • Glucocorticoids, such as cortisol, are bound to transcortin or corticosteroid-binding globulin (CBG) in the circulation

    Effects of Glucocorticoids

    • Inhibit ACTH secretion, representing a negative feedback response on the pituitary
    • Produce personality changes, including irritability, apprehension, and inability to concentrate, in adrenal insufficiency
    • Increase plasma glucose levels, providing extra glucose to vital organs like the brain and heart
    • Raise plasma lipid levels and increase ketone body formation in diabetics
    • Decrease the number of circulating eosinophils and basophils, and increase neutrophils, platelets, and red blood cells

    Effects of Mineralocorticoids

    • Increase reabsorption of Na+ from the urine, sweat, saliva, and colon contents
    • Cause retention of Na+ in the ECF, expanding ECF volume
    • Produce a K+ diuresis and increase urine acidity
    • Bind to cytoplasmic receptors, altering transcription of mRNAs and increasing epithelial sodium channels (ENaCs)

    Resistance to Stress

    • Stress activates homeostatic reactions that tend to restore the previous state
    • ACTH secretion is essential for survival during severe stress
    • Glucocorticoids may maintain vascular reactivity to catecholamines

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