Hypothalamic-Pituitary Relationships and Biofeedback Pt. II Flashcards
what does the adrenal medulla secrete?
catecholamines- epinephrine and norepinephrine
What are the zones of the adrenal cortex from outer to inner?
zona glomerulosa, zona fasciculata, and zona reticularis
what does the zona glomerulosa secrete?
mineralocortcicoids (aldosterone)
what does the zona fasciculata secrete?
glucocorticoids (cortisol)
what does the zona reticularis secrete?
androgens
what stimulates the release of CRH from the hypothalamus?
stress and the circadian rhythm
what is the effect of cortisol on the immune system?
immunosuppression
what is the effect of cortisol on the liver?
gluconeogenesis
what is the effect of cortisol on the muscles?
protein catabolism
what is the effect of cortisol on adipose tissue?
lipolysis
cortisol has negative feedback loops where?
directly inhibits the anterior pituitary from secreting more ACTH, directly inhibits the hypothalamus from secreting more CRH, and also suppresses infection and inflammation
do androgens secreted by the zona reticularis have any feedback loops on the anterior pituitary or hypothalamus
NO ONLY CORTISOL DOES
when are the secretory rates of cortisol the highest?
in the early morning
what is the main stimulus for aldosterone secretion by the zona glomerulosa?
decreased Na+ or increased K+ in the blood or decreased blood pressure
if you have low BP/ low Na+ in the blood and high K+ in the blood what is stimulated?
the kidneys are stimulated to release renin
what does renin cause?
the conversion of angiotensinogen to angiotensin 1 (which is inactive)
what catalyzes the angiotensin 1 into its active form and what is the active form?
ACE and the active form is angiotensin II
what does angiotensin II do?
it acts on the zona glomerulosa to secrete aldosterone
what are the effects of aldosterone?
it causes BP to increase, Na+ levels in the blood to increase–> water and Na+ reabsorption
What are the signs of cushing’s syndrome?
truncal obesity, moon face, buffalo hump, easy bruising, HTN, acne
cushing’s syndrome is a result of what?
chronic excess of glucocorticoids
what is the low-dose dexamethasone supression test used for?
to test for Cushing’s syndrome
what would be a normal test finding of a low dose dexamethasone test?
low cortisol levels
what would be an abnormal test finding for a low dose dexamethasone test?
high/normal cortisol levels
what would low levels of cortisol after a high dose of dexamethasone indicate?
cushing’s disease
what is cushing’s disease?
an anterior pituitary tumor
what would high levels/normal levels of cortisol and high levels of ACTH after a high dose of dexamethasone indicate?
an ectopic ACTH secreting tumor
what would high/normal levels of cortisol and low levels of ACTH after a high dose of dexamethasone indicate?
adrenal cushing’s syndrome
if there is long term treatment of exogenous glucocorticoids, what would happen?
the anterior pituitary would stop releasing ACTH and therefore the zona fasciculata would atrophy since it wasn’t being stimulated
what are some examples of synthetic glucocorticoids?
prednisone, methylprednisone, and dexamethasone
what is the term for excessive exogenous glucocorticoids?
Iatrogenic
what would the levels look like for Iatrogenic cushing’s syndrome?
decreased CRH, decreased ACTH, and decreased cortisol (the exogenous glucocorticoids mimic cortisol so there are symptoms like there is excessive amounts of cortisol when there really is not)
what is the primary action of aldosterone?
renal sodium reabsorption
why is addison disease often characterized by hyperpigmentation of the skin?
becasue addison disease leads to increased levels of ACTH and the ACTH contains the alpha-MSH fragment which leads to melanin synthesis
what type of hormone is ACTH?
peptide hormone
what is ACTH derived from?
POMC
what are the lab levels for addison disease?
decreased Na+ in blood and increased K+ in blood
if you have a primary adrenal insufficiency what would the levels of cortisol and aldosterone look like?
they would both be low
if you have a secondary adrenal insufficiency what would the levels of cortisol and aldosterone look like?
the levels of cortisol would be low due to the low ACTH, but the aldosterone levels would be normal
what are some causes of addison disease (primary adrenal insufficiency)
autoimmune disease, adrenal hemorrhage secondary to N. meningitidis, infection with tuberculosis or N. meningitidis
what is primary hyperaldosteronism?
excessive release of aldosterone from the adrenal cortex
what is conn’s syndrome?
it is an adenoma in the adrenal cortex (zona glomerulosa) that causes increased secretion of aldosterone
what is secondary hyperaldosteronism?
excessive renin secretion by the juxtaglomerular cells in the kidney
if you have ambiguous genitalia, hypertension, masculinization, and low potassium levels, what deficiency would you expect?
11-beta hydroxylase deficiency
if you have ambiguous genitalia, hypotension, and masculinization, what deficiency would you expect?
21-Beta-hydroxylase deficiency
if you have a 21-B hydroxylase deficiency what would the levels look like?
decreased cortisol, increased K+, decreased Na+ and increased renin
if you have a 11-Beta-hydroxylase deficiency what would the levels look like?
increased Na+ levels, decreased K+ levels, decreased renin levels, decreased levels of cortisol
an individual with an 11-B-hydroxylase deficiency would have hypertension due to what?
the accumulation of DOC, DOC can have mineralocorticoid activity
what are you blocking with a 17-alpha hydroxylase deficiency?
cortisol production and androgen production–> so heavily leans on aldosterone production
what are the symptoms of 17-alpha-hydroxylase deficiency?
hypertension and feminization
the mineralocorticoid receptor is protected from activation by cortisol by what?
the enzyme 11B-HSD2
all congenital adrenal enzyme deficiencies are characterized by what?
enlargement of both adrenal glands due to increased ACTH stimulation due to low levels of cortisol (adrenal hyperplasia)
if a patient presents with hypertension, headaches, palpitations, and sweating, what might you suspect?
increased catecholamines from the adrenal medulla caused from a pheochromocytoma
synthesis of catecholamines is under the control of what?
sympathetic activity and the CRH-ACTH-cortisol axis
what effect does cortisol have on epinephrine?
cortisol upregulates PNMT enzyme which converts norepinephrine to epinephrine
if there are high levels of metanephrine, what would you expect?
increased catecholamine production (epinephrine)
if there are high levels of normetanephrine, what would you expect?
high levels of catecholamine production (norepinephrine)
what converts catecholamines into their byproducts?
COMT
epinephrine has a higher affinity for what receptor type?
B2
