Physio: Endocrine - Pituitary Gland

Front 1

How are hormones transported from the hypothalamus to the a/p?

Back 1

hormones are synthesized in hypothalamic cell bodies, released in median eminence, diffues into capillary plexus of hypophysial portal vessels, which deliver hormone directly to a/p

Front 2

How are hormones transported from teh hypothalamus to the p/p?

Back 2

synthesized in cell bodies in supraoptic (ADH) and paraventricular (oxytocin) nuclei of hypothal, transported down axons in neurosecretory vessels, released into p/p by action potential, diffuse into venous capillary plexus

Front 3

From what primitive structure is the a/p derived?

Back 3

primative foregut

Front 4

From what primitive tissue is the p/p derived?

Back 4

neural tissue

Front 5

What are the properties of the TSH, FSH, LH family?

Back 5

glycoproteins; identical alpha subunits and different beta subunits

Front 6

What hormones are included in the ACTH family?

Back 6

ACTH, MSH, beta-lipotropin, beta-endorphin

Front 7

What is the common precursor for the hormones of the ACTH family?

Back 7

POMC (pro-opiomelanocortin)

Front 8

What factors increase s/c of growth hormone?

Back 8

sleep, stress, puberty, starvation, exercise, hypoglycemia

Front 9

What factors decrease s/c of growth hormone?

Back 9

somatostatin, somatomedins, obesity, hyperglycemia, pregnancy

Front 10

What is the action of GHRH?

Back 10

stimulate s/c of growth hormone from a/p

Front 11

What is the action of somatostatin (SRIF)?

Back 11

inhibit s/c of growth hormone from a/p

Front 12

What 3 factors/hormones provide negative feedback for the production of growth hormone?

Back 12

1. somatomedians
2. growth hormone
3. GHRH

Front 13

What is the mechanism of negative feedback by somatomedians (i.e. insulin-like growth factors (IRF))?

Back 13

somatomedians directly inhibit release of GH from a/p, and stimulate s/c of somatostatin (SRIF) from hypothalamus

Front 14

How does growth hormone feed back upon itself?

Back 14

GH stimulates somatostatin (SRIF), which inhibits release of GH from a/p

Front 15

What is the feedback mechanism of GHRH?

Back 15

GHRH directly inhibits its own release from the hypothalamus (ultrashort-loop feedback)

Front 16

Where is growth hormone synthesized, and by what type of cells?

Back 16

by somatotrophs in the a/p

Front 17

What are the direct effects of growth hormone?

Back 17

diabetogenic effect (dec gluc uptake), inc lipolysis, inc protein synth in musc & inc in lean body mass, inc production of IGF (insulin-like growth factors)

Front 18

What are the main indirect effects of growth hormone?

Back 18

growth-promoting effects: proliferation of chondrocytes, inc linear growth, inc musc size, body mass, & organ size

Front 19

What factor mediates the indirect effects of growth hormone? Where in the body is this factor produced?

Back 19

IGF (insulin-like growth factors), aka somatomedians; produced in liver

Front 20

What are some possible causes of growth hormone deficiency?

Back 20

a/p deficiency (no GH), GH receptor deficiency, hypothalamic deficiency (no GHRH), failure to generate IGF in liver

Front 21

What is used to treat growth hormone excess?

Back 21

somatostatin analogs (octreotide)

Front 22

What results from hypersecretion of growth hormone before puberty? After puberty?

Back 22

before puberty: inc linear growth (gigantism)

after puberty: inc periosteal bone growth, inc organ size, glucose intolerance

Front 23

What results from growth hormone deficiency?

Back 23

failure to grow, short stature, mild obesity, delayed puberty

Front 24

What are the major actions of prolactin?

Back 24

stimulate milk production (lactogenesis) and breast development (and inhibits ovulation)

Front 25

What is the hypothalamic releasing factor for prolactin?

Back 25

TRH (thyrotropin releasing factor) (by altering transcription of prolactin gene)

Front 26

What is the hypothalamic inhibitory factor for prolactin?

Back 26

PIF (prolactin inhibiting factor), aka dopamine

*prolactin s/c is tonically inhibited by PIF, thus interruption of hypothal-pit tract causes prolactin s/c*

Front 27

What is the major negative feedback mechanism for prolactin?

Back 27

prolactin stimulates DA s/c

Front 28

What are the most important stimuli for prolactin secretion?

Back 28

pregnancy and breast-feeding (suckling)

Front 29

Via what mechanism does prolactin inhibit ovulation?

Back 29

it inhibits the synthesis and release of GnRH (accounts for decreased fertility during breast-feeding)

note: inc prolactin in males inhibits spermatogenesis and causes infertility

Front 30

What could cause prolactin deficiency? What would the result be?

Back 30

destruction of lactotrophs or entire a/p; failure to lactate

Front 31

What could cause prolactin excess?

Back 31

destruction of hypothalamus, interruption of hypothalamic-hypophysial tract (results in loss of tonic inhibition by DA), or prolactinomas

Front 32

What are the major sx of prolactin excess?

Back 32

galactorrhea (excessive lactation), dec libido, failure to ovulate, amenorrhea (due to inhibitory effect on GnRH)

Front 33

What could be used to treat prolactin excess?

Back 33

DA agonist (e.g. bromocriptine)

Front 34

What 2 hormones are secreted by the p/p, and where are they synthesized?

Back 34

ADH, oxytocin; supraoptic and paraventricular nuclei (respectively)

Front 35

What are the major actions of ADH (aka vasopressin)?

Back 35

Inc water permeability of pricipal cells of late distal tubule and collecting ducts (via V2 receptor - cAMP mech)

constricts vascular smooth muscle (via V1 receptor - IP3/Ca mech)

Front 36

What are some factors that increase ADH secretion?

Back 36

inc serum osmolarity, volume contraction, pain, nausea, hypoglycemia, nicotine, opiates

Front 37

What are some factors that decrease ADH secretion?

Back 37

dec serum osmolarity, etoh, alpha agonists, ANP

Front 38

What type of receptor senses hypovolemia?

Back 38

baroreceptors in the left atrium, aortic arch, and carotid artery

Front 39

Pt with large volumes of dilute urine, high serum osmolarity, and low ADH. Disease? Tx?

Back 39

Central diabetes insipidus; failure of p/p to s/c ADH, collecting ducts impermeable to water; treat w/ADH analogue (dDAVP)

Front 40

Pt with large volumes of dilute urine, high serum osmolarity, and high ADH. Disease? Tx?

Back 40

Nephrogenic diabetes insipidus; principal cells of collecting ducts are unresponsive to ADH (defect in V2 receptor, G-protein, or AC), w/inc ADH due to neg feedback; treat w/ thiazide diuretics (interferes w/dilution of urine)

Front 41

Pt w/inappropriately concentrated urine (relative to the decreased serum osmolarity). Dx? Tx?

Back 41

SIADH (syndrome of inappropriate ADH); ADH is secreted from autonomous site (e.g. oat cell carcinoma of lung); treat w/ADH antagonist (demeclocycline) or water restriction

Front 42

What are the major actions of oxytocin?

Back 42

milk ejection, contraction of uterine smooth muscle (used to induce labor and reduce postpartum bleeding)

Front 43

What are the major stimulatory factors for oxytocin?

Back 43

suckling, sight/sound of infant, dilation of cervix, orgasm