Pituitary

Question 1

Anterior lobe of pituitary

Answer 1

Rathke’s pouch
Ectodermal diverticulum

Hormones: “FLAT PiG”

FSH
LH
ACTH
TSH
Prolactin
Intermidate – MSH
GH

Question 2

Posterior lobe of pituitary

Answer 2

Invagination of hypothalamus – neuroectoderm

ADH
Oxytocin

Question 3

ADH

Answer 3

Decrease urine output
Vascular constriction

Increase ADH: nicotine, opiates

Decrease ADH: ethanol, atrial natriuretic factor, decrase serum osmolality

Question 4

Oxytocin

Answer 4

Uterine contraction – induced by cervix dilation

Milk ejection – stimulated by suckling

Inhibited by alcohol and stress

Question 5

GnRH

Answer 5

Pulsatile release leads to FSH and LH secretion

Inhibited by prolactin

Continuous GnRH – inhibits FSH and LH

Question 6

FSH

Answer 6

Granulosa cell follicle development
Spermatogenesis

Inhibited by inhibin

Question 7

LH

Answer 7

Progesterone production
Theca lutein cells
-ovulation
-form corpus luteum

Leydig cells -> testosterone

Inhibited by progesterone and testosterone

Question 8

ACTH

Answer 8

Release stimulated by CRH and stress
Inhibited by cortisol

Acts on adrenal cortex to release cortisol

Question 9

MSH

Answer 9

Intermediate lobe of pituitary

-> melanin release by melanocytes

Question 10

TRH

Answer 10

Stimulates TSH release, acts on thyroid to release T3, T4

Inhibited by T3, T4

Question 11

GH

Answer 11

Stimulated by GHRH, exercise, sleep, puberty, hypoglycemia, estrogen, stress, endogenous opioids

Cause:
Release of IGF-1 -> growth 
Decreased glucose uptake
Increased protein synthesis
Increased organ size
Increase lean body mass

Inhibited by GHIH (somatostatin), somatomedins, IGF1, obesity, pregnancy, hyperglycemia

Question 12

Prolactin

Answer 12

Stimulated by TRH

Causes milk production and secretion, breast development

Inhibits ovulation
Inhibits GnRH

Release inhibited by dopamine

Question 13

POMC

Answer 13

Precursor to ACTH and MSH

Contains hormonal peptides sequence for: lipotropin, beta-endorphin

Question 14

Primary adrenal insufficiency

Answer 14

Production of cortisol low

Hypothalamus and pituitary make ACTH, trying to stimulate the adrenals to make more cortisol

When ACTH concentration is excessive, MSH receptors in skin are stimulated -> skin hyperpigmentation

Question 15

Hyperprolactinemia

Answer 15

MC anterior pituitary hormone abnormality

Causes by:
Pregnancy/nipple stimulation
Stress – physical or psychological
Prolactinoma – assoc w/ bitemporal hemianopia
Dopamine antagonists – anti psychotics (haloperidol, risperidone), domperidone, metoclopramide

Premenopausal female sx: hypogonadism -> infertility, oligo/amenorrhea, rarely galactorrhea

Post menopausal: no sx – already hypogonadal

Males: hypogonadism (low T) -> decreased libido, impotence, infertility (low sperm counts), gynecomastia, rarely galactorrhea

Question 16

Pituitary adenoma

Answer 16

Prolactinoma ->
Amenorrhea
Galactorrhea
Low libido
Infertility
Bitemporal hemianopia

Tx: bromocriptine, cabergoline (DA agonists)
Surgical resection

Question 17

Acromegaly

Answer 17

Too much GH
Adult

Large tongue – deep furrows, indentations (teeth)

Increased spacing of teeth
Deep voice
Large hands and feet
Coarse facial features
Impaired glucose tolerance -> DM

Dx: elevated IGF-1
OGTT – check GH level not glucose
-normally glucose suppresses GH

Tx: surgical resection
Octreotide

Question 18

Gigantism

Answer 18

Too much GH in kids

Excess bone growth of linear bones

Tall and big children

Dx: elevated IGF-1
OGTT – check GH level not glucose
-normally glucose suppresses GH

Tx: surgical resection
octreotide

Question 19

Somatostatin

Answer 19

D cells in GI mucosa
Pancreatic islet cells
Nervous system

Actions:
Reduces splanchnic blood flow, reduces GI motility, gallbladder contraction, inhibits secretion of most GI hormones
Deceases exocrine secretions in the pancreas
Decreases hormone secretion in CNS, PNS, endocrine organs

Question 20

Clinical uses of somatostatin analogs

Answer 20

octreotide, somatostatin LAR, lanreotide –P

pituitary excesses (except prolactin): acromegaly, thyrotropinoma, ACTH-secreting tumors

GI endocrine excess: Zollinger-Ellison Sn, carcinoid sn, VIPoma, glucagonoma, insulinoma

Diarrheal diseases

Need to reduce splanchnic circulation: portal hypertension (bleeding varices), bleeding peptic ulcers

Question 21

Sheehan syndrome

Answer 21

Postpartum hemorrhage -> underperfusion of pituitary

Pituitary necrosis and hypopituitarism

Aglactorrhea d/t deficiency of prolactin
Amenorrhea after delivery
Secondary hypothyroidism -> fatigue, cold intolerance, wt gain
Hyponatremia (rare)