60 Questions
What is the effect of glucocorticoids on plasma glucose levels?
They increase plasma glucose levels, especially for the brain and heart.
What is the effect of glucocorticoids on ketone body formation in diabetics?
They increase ketone body formation.
What is the effect of glucocorticoids on ACTH secretion?
They inhibit ACTH secretion.
What is the effect of glucocorticoids on the nervous system in adrenal insufficiency?
They reverse the appearance of electroencephalographic waves slower than the normal β rhythm.
What is the effect of glucocorticoids on water metabolism in adrenal insufficiency?
They repair the ability to excrete a water load.
What is the effect of glucocorticoids on the number of circulating eosinophils?
They decrease the number of circulating eosinophils.
What is the main fate of cortisone formed in the liver?
It is promptly reduced and conjugated to form tetrahydrocortisone glucuronides
What is the main difference between aldosterone and cortisol in terms of protein binding?
Aldosterone is bound to protein to a lesser extent than cortisol
What is the main derivative of aldosterone formed in the liver?
18-glucuronide
What is the primary adrenal androgen secreted?
Dehydroepiandrosterone
What percentage of urinary ketosteroids in men come from the adrenal or cortisol metabolism in the liver?
Two-thirds
What is the primary effect of androgens?
Masculinizing effects and protein anabolism
What is the main function of cholesterol ester hydrolase in steroid biosynthesis?
To form free cholesterol from cholesterol ester
What is the effect of ACTH binding to adrenocortical cells?
Prompt increase in the formation of pregnenolone and its derivatives
What is the primary function of the sterol carrier protein?
To transport cholesterol to the mitochondria
What is the effect of estrogen on CBG production?
Increased production of CBG
What is the ratio of mineralocorticoid activity of deoxycorticosterone to aldosterone?
3%:100%
What is the precursor of all steroids in the adrenal gland?
Cholesterol
What is a characteristic of the skin and subcutaneous tissues in patients with Cushing syndrome?
Thin and poorly developed
What is the primary cause of acne and facial hair increase in patients with Cushing syndrome?
Increased secretion of adrenal androgens
What is the characteristic redistribution of body fat in patients with Cushing syndrome?
Fat accumulation in the abdominal wall, face, and upper back
What percentage of patients with Cushing syndrome are hypertensive?
85%
What is the effect of glucocorticoids on the inflammatory response to tissue injury?
They inhibit the inflammatory response
What is the effect of glucocorticoids on manifestations of allergic disease?
They suppress the manifestations of allergic disease
What is the primary function of the aldosterone-secreting mechanism?
Defense of intravascular volume
What happens to aldosterone secretion when one rises from the supine to the standing position?
It increases
What is a factor that affects Na+ excretion, aside from aldosterone secretion?
Glomerular filtration rate
What stimulates adrenocortical secretion and affects primarily the secretion of aldosterone in small doses?
Injections of angiotensin II
What is increased before any consistent decrease in blood pressure takes place due to dietary sodium restriction?
Aldosterone secretion and renin secretion
What happens to Na+ excretion when one rises from the supine to the standing position?
It decreases
What is the primary consequence of increased plasma glucose levels in vital organs during adrenal insufficiency?
Improved glucose uptake in the brain and heart
Which of the following is a characteristic of glucocorticoid deficiency in the nervous system?
Appearance of electroencephalographic waves slower than the normal β rhythm
What is the consequence of glucocorticoid deficiency in water metabolism?
Increased risk of water intoxication
What is the effect of glucocorticoids on the circulation of blood cells?
Increase in circulating neutrophils, platelets, and red blood cells
What is the consequence of glucose infusion in patients with adrenal insufficiency who have not received glucocorticoids?
High fever followed by collapse and death
What is the primary effect of glucocorticoids on the pituitary?
Inhibition of ACTH secretion
What is the primary reason for the characteristic 'buffalo hump' appearance in patients with Cushing syndrome?
Redistribution of body fat in the abdominal wall, face, and upper back
What is the primary mechanism by which glucocorticoids inhibit the inflammatory response to tissue injury?
By inhibiting the activity of inflammatory cells
What is the primary cause of significant K+ depletion in patients with Cushing syndrome?
Salt and water retention
What is the primary effect of increased glucocorticoid secretion on blood vessels?
Direct effect on blood vessels leading to hypertension
What is the primary reason for the characteristic 'moon-faced' appearance in patients with Cushing syndrome?
Facial obesity due to salt and water retention
What is the primary effect of glucocorticoids on allergic disease?
Suppression of manifestations of allergic disease
What percentage of androgen activity do adrenal androgens have in comparison to testosterone?
Less than 20%
What regulates secretion of adrenal androgens?
ACTH
What is the effect of excess adrenal androgens in adult males?
Accentuation of existing masculine characteristics
What is androstenedione converted to in fat and other peripheral tissues?
Testosterone and estrogens
What is the mechanism of action of glucocorticoids?
Binding to glucocorticoid receptors
What is the effect of glucocorticoids on peripheral tissues?
Anti-insulin action
What is the definition of stress in biology?
Any change in the environment that changes or threatens to change an existing optimal steady state
What is the effect of increased ACTH secretion in response to stress?
It is essential for survival when the stress is severe
What is the result of prolonged increases in plasma glucocorticoids?
Cushing syndrome
What is the role of circulating glucocorticoids in the body's response to stress?
To maintain vascular reactivity to catecholamines
What is a characteristic of patients with Cushing syndrome?
Protein depletion
What is the relationship between the sympathetic nervous system and ACTH secretion?
The sympathetic nervous system stimulates ACTH secretion
What is the effect of aldosterone on Na+ reabsorption?
It increases Na+ reabsorption from the urine and sweat.
How does aldosterone stimulate the synthesis of ENaCs?
By increasing the insertion of ENaCs into the cell membrane from a cytoplasmic pool.
What is the effect of chronic adrenal insufficiency on ACTH secretion?
It increases ACTH synthesis and secretion.
What is the consequence of the exchange of Na+ for K+ and H+ in the renal tubules?
K+ diuresis and increased urine acidity.
What is the mechanism of action of aldosterone?
It binds to a cytoplasmic receptor, and the receptor-hormone complex moves to the nucleus.
What is the effect of aldosterone on ECF volume?
It increases ECF volume.
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
Learn about the biosynthesis of steroids in the adrenal gland, including the role of cholesterol and enzymes involved in the process.
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