Pituitary and Fluid Homeostasis

Question 1

The posterior pituitary is an extension of

Answer 1

the anterior hypothalamus (neural connections)

Question 2

The posterior pituitary secretes what 2 neurohormones

Answer 2

Oxytocin and vasopressin

Question 3

Proneurohormones of the posterior pituitary

Answer 3

pro neurohormones are cleaved in the axon and released into the synaptic cleft along with the neurophysin

Question 4

neurophysin

Answer 4

carrier proteins that transport neurohormones down the axon

Question 5

Action of Oxytocin

Answer 5

myoepithelial surrounding alveoli in breast contraction and contraction of uterine myometrium

Question 6

Diabetes Insipidus

Answer 6

lack of ADH or response to ADH

Question 7

Vasopressin V2 receptor Action

Answer 7

bind V2 receptors in distal tubule or collecting duct to promote insertion of aquaporins

Question 8

Vasopressin V2 receptor mechanism

Answer 8

Adenylyl cyclase and cAMP

Question 9

Vasopressin V1 receptor Action

Answer 9

vasoconstriction to increase TPR and BP (during hemorrhaging)

Question 10

V1 receptors

Answer 10

less affinity, require increased [AVP] for activation

Question 11

Osmoregulators regulate plasma osmolality

Answer 11

cell volume and firing frequency of APs are linked (high plasma Osm = decreased cell V = HIGH firing rate of AP)

Question 12

High firing rate of osmoregulators causes

Answer 12

increased release of AVP

Question 13

Plasma osmolality threshold is

Answer 13

280

Question 14

Is plasma osmolality is <280 then

Answer 14

osmoregulators stop firing APs and vasopressin stops secreting

Question 15

What monitors blood volume

Answer 15

stretch receptors in venous system and baroreceptors in the arterial system

Question 16

Stretch receptors and baroreceptors

Answer 16

stretching causes increased AP and release of INHIBITORY NT that decreases vasopressin

Question 17

An increase in blood volume causes

Answer 17

a decreased sensitivity of the osmoreceptors

Question 18

A decrease in blood volume causes

Answer 18

an increased sensitivity of the osmoreceptors

Question 19

If there are conflicting signals from stretch receptors and osmoregulators, which signal overrides the other

Answer 19

stretch receptors indicating the status of BV and BP

Question 20

What stimulates thirst

Answer 20

osmoreceptors (threshold in 295), osmoreceptors at 280 already increase vasopressin

Question 21

What other factors stimulate vasopressin release

Answer 21

high body temp, hypoxia, stress, exercise, endorphins, progesterone, nausea, pain

Question 22

What factors inhibit vasopressin release

Answer 22

etOH, lithium, decreased body temp, glucocorticoids

Question 23

anterior pituitary is connected to

Answer 23

hypothalamus via portal veins (hypothalamo-hypophyseal veins)

Question 24

Hypophysiotrophic hormones

Answer 24

hypothalamic hormones stimulate differentiation and proliferation (trophic effects) in the anterior pituitary

Question 25

6 hypothalamic hormones

Answer 25

thyrotropin-releasing hormone (TRH), corticotropin releasing hormone (CRH), gonadotropin releasing hormone (GnRH), growth-hormone releasing hormone (GHRH), dopamine (DA), and somatostatin (SS)

Question 26

3 families of hormones released by the anterior pituitary

Answer 26

glycoproteins, somatomammotropins, pro-opiomelanocortin

Question 27

glycoproteins from the anterior pituitary

Answer 27

follicle stimulating hormone (FSH), luteinizing hormone (LH), thyroid stimulating hormone (TSH)

Question 28

somatomammotropins from the anterior pituitary

Answer 28

growth hormone (GH), prolactin

Question 29

pro-opiomelanocortin from the anterior pituitary

Answer 29

ACTH

Question 30

anterior pituitary hormone release is regulated by

Answer 30

hormones fromt he hypothalamus

Question 31

if the anterior pituitary is separated from the hypothalamus what would happen to the secretion of the anterior pituitary hormones

Answer 31

they would all decrease except prolactin (normally inhibited by the hypothalamus)

Question 32

Anterior pituitary hormones are

Answer 32

trophic - regulating growth, development, secretion of adrenal gland, thyroid gland, gonads, and mammary gland

Question 33

Hypothalamic hormones are secreted by

Answer 33

neurosecretory cells

Question 34

hypothalamis hormones are all ___________ except dopamine which is _________

Answer 34

peptides; catecholamines

Question 35

Hypothalamic hormones stimulate anterior pituitary hormone release except for

Answer 35

prolactin; which is inhibited

Question 36

Long-loop negative feedback

Answer 36

third target endocrine gland may suppress secretions from pituitary and hypothalamus

Question 37

Short-loop nehative feedback

Answer 37

pituitary suppresses secretion from the hypothalamus