more hormones

Question 1

prolactin regulation; function

Answer 1

stimulates milk production; inhibits ovulation/spermatogenesis, inhibits libido
secretion from the hypothalamus is inhibited by dopamine. prolactin inhibits its own secretion by increasing dopamine synthesis.
TRH increases prolactin secretion.

Question 2

Treatment of prolactinoma

Answer 2

dopamine agonists- bromocriptine

Question 3

growth hormone: function; regulation

Answer 3

function: stimulates linear growth and muscle mass through IGF-1/somatomedian secretion. INCREASES INSULIN RESISTANCE (diabetogenic).
regulation: GHRH promotes release in pulses; highest during sleep/exercise. SECRETION INHIBITED BY GLUCOSE AND SOMATOSTATIN
(excess causes acromegaly/gigantism)

Question 4

Antidiuretic hormone: synthesis, function, regulation

Answer 4

synthesized in the supraoptic nucleus of the hypothalamus; released by posterior pituitary.
regulates serum osomlarity with V2 receptors and BP (V1 receptors). mostly works on principle cells of the collecting duct.

Question 5

ADH pathology

Answer 5

Low in central diabetes insipidis, high or normal in nephrogenic diabetes insipidis and primary polydipsia
nephrogenic diabetes insipidis can be caused by a mutation in V2 receptor.
desmopressin is an ADH analog that is used as treatment for DI.

Question 6

17-alpha hydroxylase deficiency: defect, symptoms, labs (incl. K),

Answer 6

17-alpha hydroxylase converts pregnenolone to 17-hydroxypregnenolone. without this, cholesterol gets shunted toward aldosterone and can’t make cortisol or androgens.
symptoms: high mineralocorticoids, low cortisol, low sex hormones.
hypertension, hypokalemia, decr. DHT.
XY: pseudohermaphriditis.
XX: no secondary sexual development
(this is the enzyme that moves stuff DOWN a layer)

Question 7

21-hydroxylase deficiency: defect, symptoms, labs)

Answer 7

can’t convert progesterone or 17-hydroxyprogesterone to aldo or cortisol. everything shunted towards androgen production.
mineralocorticoids and cortisol are low, sex hormones are high.
Labs: hypotension, hyperkalemia, incr. renin, incr. 17-hydroxyprogesterone.
salt wasting in infancy, precocious puberty.
XX: virilization

Question 8

11 beta hydroxylase deficiency: defect, symptoms, labs

Answer 8

this will also decr. aldo and cortisol because it is part of their synthesis.
 however, the mineralocorticoid intermidiate that piles up, 11-deoxycorticosterone, still works, so there is no salt wasting.
cortisol is low, aldo is low. sex hormones are high.
see hyptertension (low renin)
XX virilization

Question 9

Generally, what are the affects of cortisol?

Answer 9

BIG FIB:
blood pressure increase, incr. insulin resistance, incr. gluconeogenesis, lipolysis, and proteolysis, decr. fibroblast activity, decr. inflammatory and immune responses, decr. bone formation (decr. osteoblast activity)

Question 10

how does cortisol cause immunosuppression?

Answer 10

inhibits production of leukotrienes and prostaglandins. inhibits leukocyte adhesion and causes neutrophilia, blocks histamine release from mast cells, reduces eosinophils, blocks IL-2 production. this can cause TB reactivation and candidiasis

Question 11

What cells make PTH? What does PTH do?

Answer 11

chief cells of parathyroid
PTH goal: incr. blood Ca:
1. incr. bone resorption of Ca and PO4 3- by incr. production of macrophage colony-stimulating factor and RANK-L (receptor activator of NF-kappaB ligand). RANK-L (on osteoclasts) binds RANK on osteoblasts –> osteoclast stim and incr. Ca. though it may be that blasts are also stimulated?
2. incr. kidney resorption of Ca in DCT
3. decr. PO4 3- in PCT
4. incr. 1,25-(OH) D3 production by stimulating 1alpha hydroxylase

Question 12

What regulates PTH secretion?

Answer 12

low Ca and low Mg cause incr PTH. VERY low Mg causes decr. PTH. very low Mg causes: diarrhea, aminoglycosides, diuretics, and EtOH abuse
high 1,25-(OH)2 vitamin D also inhibits PTH secretion (feedback)

Question 13

phosphate homeostasis

Answer 13

low serum phosphorus cause incr. conversion to 1,25 vitamin D, wich releases phosphate from matrix and increases intestinal phsophate reabsorption

Question 14

In what forms does plasma calcium exist? homeostasis?

Answer 14

plasma Ca exists in ionized form, bound to albumin, or bound to anitons. increase in pH –> incr. affinity of albumin to bind Ca –> clinical manifestations of hypocalcemia

Question 15

calcitonin

Answer 15

parafollicular cells of thyroid. decreases bone resorption of Ca. regulation: incr. serum Ca causes calcitonin secretion.