59 Questions
What is the primary function of the adrenal medulla in relation to the nervous system?
It is functionally related to the sympathetic nervous system
What percentage of the adrenal gland is comprised of the adrenal medulla?
20% of the tissue
What is the primary enzyme responsible for the conversion of norepinephrine to epinephrine?
Phenylethanolamine-N-methyltransferase
What is the approximate percentage of epinephrine secreted by the adrenal medulla?
80% of the catecholamines
What is the origin of the adrenal medulla?
Neuroectodermal origin
What are the two main catecholamines secreted by the adrenal medulla?
Norepinephrine and epinephrine
What is the primary function of the catecholamines produced by the adrenal medulla?
Coordinating the bodily 'fight-or-flight' response to fear, stress, exercise, or conflict
What is the primary function of the zona glomerulosa in the adrenal cortex?
Regulating renal function and blood pressure through aldosterone production
What is the role of dopamine in the adrenal medulla?
Increasing heart rate and blood pressure
What is the collective term for the >24 steroid hormones produced by the adrenal cortex?
Corticosteroids
Which hormone is responsible for regulating blood pressure through its effect on renal function?
Aldosterone
What is the primary function of the zona reticularis in the adrenal cortex?
Secreting weak androgens, such as DHEA and androstenedione
What is the rate-limiting step in the synthesis of adrenocortical hormones?
The side-chain cleavage of cholesterol to form pregnenolone
What is the primary function of mineralocorticoids?
Regulating sodium and potassium balance
Which of the following steroids is not primarily synthesized by the adrenal cortex?
Testosterone
What is the immediate precursor to all adrenocortical hormones?
Pregnenolone
What is the main site of adrenocortical hormone synthesis?
Mitochondria and endoplasmic reticulum
Which of the following is NOT essential for life?
Secretion of sex hormones by the adrenal cortex
What is the primary cause of decreased cortisol levels in Addison's disease?
Autoimmune disorder
Which of the following is NOT a symptom of Addison's disease?
Hypertension
What is the purpose of the 'feed forward' mechanism in Addison's disease?
To increase cortisol levels
What is the primary difference between Addison's disease and secondary adrenal insufficiency?
The cause of adrenal insufficiency
Which of the following is a symptom of the loss of adrenal androgens in women with Addison's disease?
Decreased libido
What is the primary treatment for Addison's disease?
Replacement of glucocorticoids and mineralocorticoids
What is the primary function of ACTH in regulating cortisol secretion?
Transfer stored cholesterol to the mitochondria and activate cholesterol desmolase
What is the diurnal pattern of cortisol secretion driven by?
The “internal clock” of the hypothalamus
What is the effect of sleep loss on the hypothalamic-pituitary-adrenal (H-P-A) axis?
Delays the recovery of the H-P-A axis
What is the characteristic of cortisol secretion?
Pulsatile and diurnal
What is the effect of coma, blindness, or constant exposure to either light or dark on the diurnal pattern of cortisol secretion?
Alters or abolishes the diurnal pattern
What is the nocturnal peak of ACTH driven by?
A burst of CRH secretion
The adrenal medulla produces more than 24 steroid hormones collectively known as corticosteroids.
False
Aldosterone is a glucocorticoid produced by the zona fasciculata of the adrenal cortex.
False
Dopamine increases heart rate and blood pressure by stimulating the adrenal medulla.
True
The zona reticularis of the adrenal cortex produces aldosterone.
False
CRH stimulates the adrenal medulla to release catecholamines.
False
The adrenal medulla is responsible for regulating blood pressure through the release of aldosterone.
False
Aldosterone increases sodium reabsorption from the tubular epithelial cells of kidney back into the blood while simultaneously moving potassium ions from the blood into the kidneys for eventual excretion in urine.
True
Elevated [K+] levels in blood decrease aldosterone secretion.
False
Mineralocorticoids increase K+ reabsorption in the kidneys.
False
Corticosterone is the primary glucocorticoid hormone in humans.
False
The rate-limiting step in the synthesis of adrenocortical hormones is catalyzed by cholesterol desmolase.
True
Corticosterone circulates in blood at 10-20-fold higher levels than cortisol.
False
The secretion of glucocorticoids by the zona fasciculata/reticularis is regulated exclusively by the hypothalamic-pituitary axis and the kidney. NOT KIDNEY
False
ACTH stimulates the transfer of stored cholesterol to the mitochondria and inhibits cholesterol desmolase.
False
The diurnal pattern of cortisol secretion is driven by the hypothalamus and the pituitary gland.
False
The highest secretory rates of cortisol occur just after falling asleep.
False
Partial acute sleep loss accelerates the recovery of the H-P-A axis.
False
The diurnal pattern of cortisol secretion is not altered or abolished by coma, blindness, or constant exposure to either light or dark.
False
In Hypocortisolism, such as Addison disease, Hyperglycemia is typically observed.
False
Cortisol induces the synthesis of lipocortin, which stimulates the enzyme phospholipase A2.
False
Cortisol up-regulates β2-adrenergic receptors on arterioles, leading to vasodilation.
False
In Hypercortisolism, blood pressure is typically decreased.
False
Cortisol increases REM sleep and decreases slow-wave sleep.
False
Glucocorticoid receptors are not found in the brain.
False
Failing to comply with a medically prescribed steroid taper can lead to Addisonian Crisis, a medical emergency with a high mortality rate.
True
Cushing's Disease is caused by an adrenal gland tumor.
False
Both Cushing's Disease and Cushing's Syndrome result from a deficiency of cortisol.
False
Dehydration is a symptom of Addisonian Crisis.
True
Cushing's Syndrome is always caused by a pituitary tumor.
False
Study Notes
Adrenal Gland Structure and Function
- Adrenal gland consists of two parts: adrenal medulla (inner zone) and adrenal cortex (outer zone)
- Adrenal medulla produces catecholamines (epinephrine and norepinephrine) and is functionally related to the sympathetic nervous system
- Adrenal cortex produces mineralocorticoids, glucocorticoids, and androgens
Adrenal Cortex Zones
- Zona glomerulosa (outer zone): produces mineralocorticoids (aldosterone)
- Aldosterone regulates sodium and potassium balance
- Enzyme aldosterone synthase is involved in its synthesis
- Zona fasciculata (middle zone): produces glucocorticoids (cortisol)
- Cortisol influences carbohydrate, fat, and protein metabolism
- Zona reticularis (inner zone): produces weak androgens (dehydroepiandrosterone and androstenedione) and some glucocorticoids
Regulation of Glucocorticoid Secretion
- Regulated exclusively by the hypothalamic-pituitary axis
- ACTH (adrenocorticotropic hormone) stimulates the transfer of stored cholesterol to the mitochondria and activates cholesterol desmolase
- ACTH has a pulsatile and diurnal secretory pattern, driving a parallel pattern of cortisol secretion
- Nocturnal peak of ACTH is driven by a burst of CRH (corticotropin-releasing hormone) secretion
Diurnal Pattern of Cortisol Secretion
- Average of 10 secretory bursts over 24 hours
- Lowest secretory rates occur during evening hours and just after falling asleep
- Highest secretory rates occur just before awakening in the morning
- Hypothalamus acts as an "internal clock" to drive the diurnal pattern
- Diurnal pattern can be shifted by altering sleep-wake cycles or abolished by coma, blindness, or constant exposure to light or dark
Effects of ACTH and Cortisol
- ACTH stimulates the synthesis of cortisol
- Cortisol has anti-inflammatory effects, induces the synthesis of lipocortin, and inhibits the production of interleukin-2 and the proliferation of T lymphocytes
- Cortisol maintains vascular responsiveness to catecholamines and up-regulates α1-adrenergic receptors on arterioles
- Cortisol also affects the central nervous system, decreasing REM sleep, increasing slow-wave sleep, and increasing awake time
Disorders Related to Adrenal Gland
- Addison's disease: a disorder characterized by the loss of glucocorticoids and mineralocorticoids, resulting in hypoglycemia, anorexia, weight loss, and weakness
- Cushing's disease: a disorder characterized by hypersecretion of ACTH from a pituitary adenoma, resulting in excess secretion of cortisol
- Cushing's syndrome: a disorder characterized by excess secretion of cortisol from an adrenal gland tumor, resulting in signs and symptoms similar to Cushing's disease
Test your knowledge on the anatomy and histology of the adrenal gland, its hormones, and their effects on the body. Learn about the synthesis, regulation, and role of adrenocortical hormones in health and wellness.
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