Adrenal Medulla & Adrenal Cortex

Flashcards about the adrenal medulla & adrenal cortex

Name the three catecholamines secreted by the adrenal medulla.

Epinephrine, norepinephrine, and dopamine.

What are the steroid hormones secreted by the adrenal cortex?

Mineralocorticoids, glucocorticoids, and androgens.

What is the primary glucocorticoid secreted by the adrenal cortex?

Cortisol

What mineralocorticoid is essential for Na+ balance and extracellular fluid volume?

Aldosterone

What primarily controls adrenocortical secretion?

Adrenocorticotropic hormone (ACTH) from the anterior pituitary.

What circulating factor independently controls mineralocorticoid secretion?

Angiotensin II

What is the function of the adrenal medulla?

Prepares the body for emergencies, the "fight-or-flight" responses.

What percentage of the adrenal gland mass does the adrenal medulla constitute?

28%

What are the two types of cells distinguished morphologically in the adrenal medulla?

Epinephrine-secreting and norepinephrine-secreting types.

In humans, what percentages of cells are epinephrine-secreting and norepinephrine-secreting types?

90% epinephrine-secreting and 10% norepinephrine-secreting.

What are the three zones of the adrenal cortex?

Zona glomerulosa, zona fasciculata, and zona reticularis.

What percentage of the adrenal gland mass does the zona glomerulosa, zona fasciculata, and zona reticularis make up?

Zona glomerulosa: 15%, zona fasciculata: 50%, and zona reticularis: 7%.

What hormones does the zona glomerulosa secrete?

Aldosterone

What hormones does the zona fasciculata secrete?

Cortisol and androgens

What hormones does the zona reticularis secrete?

Sex hormones

What enzyme is limited to the zona glomerulosa?

Active enzymatic mechanism for aldosterone biosynthesis

During fetal life, what is the major function of the large fetal adrenal cortex?

Synthesis and secretion of sulfate conjugates of androgens that are converted in the placenta to estrogens.

What is the function of the zona glomerulosa, in addition to aldosterone synthesis?

Formation of new cortical cells.

What happens to the zona fasciculata and zona reticularis immediately after hypophysectomy?

They begin to atrophy.

What maintains the zona glomerulosa after hypophysectomy?

Angiotensin II

Which hormones are synthesized by the adrenal medulla?

Norepinephrine, epinephrine, and small amounts of dopamine.

In dogs and humans, what is the primary catecholamine output in the adrenal vein?

Epinephrine

What induces adrenal medullary PNMT?

Glucocorticoids

What are the two classes of receptors norepinephrine and epinephrine act on?

α- and β-adrenergic receptors.

What effects do catecholamines have on blood glucose?

Cause glycogenolysis and influence the secretion of insulin and glucagon.

List some key characteristics of C21 steroids.

Two-carbon side chain at position 17, classified as mineralocorticoids or glucocorticoids.

List some key characteristics of C19 steroids.

Keto or hydroxyl group at position 17; have androgenic activity.

List some key characteristics of C18 steroids.

17-keto or hydroxyl group, no angular methyl group attached to position 10.

What are the steroids normally secreted in physiologically significant amounts?

Aldosterone, cortisol, corticosterone, dehydroepiandrosterone (DHEA), and androstenedione.

What is the precursor of all steroids?

Cholesterol

What stimulates ACTH secretion?

Stress

What does excess androgen secretion cause?

Masculinization and precocious pseudopuberty or female pseudohermaphroditism.

What does excess glucocorticoid secretion produce?

Cushing syndrome.

What class of hormones does Conn syndrome relate to?

Mineralocorticoids

In what organ does cortisol get metabolised?

Liver