5 HP Axis pt. 2

Question 1

true or false: TSH is expressed in one unique type of specialized cell

Answer 1

false, it’s released by different cells

Question 2

GH and PRL are _____

Answer 2

co expressed

Question 3

where is the largest portion of endocrine cells located?

Answer 3

anterior pituitary

Question 4

where is GH stored?

Answer 4

in granules

Question 5

define somatotroph

Answer 5

cells in the pituitary that produce GH (GH is also called somatotropin)

Question 6

GH is what kind of hormone? lipid or peptide?

Answer 6

peptide

Question 7

what genes are part of GH’s locus?

Answer 7

hGH-N, hCS (with A, B, V, and L isoforms),

Question 8

what hCS hormone is expressed by the placenta during midgestation?

Answer 8

hCS-V

Question 9

what are the 2 isoforms of GH?

Answer 9

22 kDA & 20 kDA

Question 10

what’s the difference between the 2 isoforms of GH?

Answer 10

there’s not a stark difference but there appears to be a difference in glycosylation and bioactivity. the larger isoform appears to be the predominant one.

Question 11

what is an application of GH?

Answer 11

treatment of dwarfism

Question 12

how is GH isolated?

Answer 12

recombinant GH is produced in a bacterial system.

it used to be extracted from 60,000 dead bodies, which was a problem because of prions :0

Question 13

expand GHRH

Answer 13

growth hormone releasing hormone

Question 14

what hormones does the hypothalamus release to regulate GH?

Answer 14

GHRH and somatostatin (SRIF)

GHRH is the stimulatory factor
SRIF is an inhibitory factor

Question 15

what favors the production of SRIF?

Answer 15

look at slide 15

Question 16

do males or females have a greater response to GHRH?

Answer 16

females

Question 17

SRIF (induces/inhibits) GH secretion

Answer 17

inhibits

Question 18

does SRIF regulate GH production?

Answer 18

no

Question 19

in what life stage is GH levels the highest?

Answer 19

fetus

Question 20

does a child or an adolescent have more GH levels?

Answer 20

adolescent

Question 21

how is an increase in GH level achieved? (frequency or amplitude?)

Answer 21

by increasing the amplitude (volume being released), not frequency

Question 22

expand GHBP

Answer 22

Growth Hormone Binding Protein

Question 23

GH circulates as a (free/bound) hormone

Answer 23

bound (to GHBP)

Question 24

true or false: growth hormone receptors have autophosphorylation proteins

Answer 24

false

Question 25

expand SOCS

Answer 25

suppressor of cytokine signaling

Question 26

what does SOCS do to GHR?

Answer 26

inhibits GH

Question 27

what happens when there's no SOCS?

Answer 27

nothing stops the body from continuing to grow

Question 28

what is the direct effect of GH?

Answer 28

GH targets cells and directly causes a response (proliferate or differentiate)

Question 29

what is the indirect effect of GH?

Answer 29

target cells to encourage production of IGF-1 then promotes proliferation or differentiation

Question 30

when is IGF-1's effects prominent

Answer 30

childhood and adolescence, not so much during the fetal stage

Question 31

when does longitudinal growth of bones cease?

Answer 31

when concentration of GH decreases. this causes a fusion of the epiphyses

Question 32

is GH present in adults?

Answer 32

yeah

Question 33

list some functions of GH in adults (6)

Answer 33

- optimizes body composition, physical functions (strength/height), and substrate metabolism - regulates glucose, fat, and protein metabolism - enhances lipolysis and FA oxidation (application in fasting) - reduces urea synthesis and excretion (spares proteins) - inhibits insulin stimulated glucose uptake - induces insulin secretion

Question 34

GH seems to have contradictory effect on glucose metabolism. what's the point?

Answer 34

it depends on context. GH will do what it needs to accordingly

Question 35

expand IGF

Answer 35

insulin-like growth factor

Question 36

does GH effect IGF 1 or 2? or both?

Answer 36

only 1.

Question 37

all cells produce IGF but don't release into the bloodstream. this classifies them as _____

Answer 37

paracrine

Question 38

where is IGF-I produced?

Answer 38

liver and body tissues. only liver is endocrine.

Question 39

role of IGF-II?

Answer 39

fetal development

Question 40

why are IGFs called that?

Answer 40

they have similar amino acid sequencing to insulin

Question 41

how do cells locally regulate IGF-I?

Answer 41

binding protein and binding protein proteases. this determines how much IGF is bioavailable. the more proteases the more free IGF-I available

Question 42

what's the main difference between GH and IGF-I receptors?

Answer 42

IGF has autophosphorylation capability

Question 43

how is GH release regulated? (5)

Answer 43

- balance between GHRH and SRIF - feedback by IGF-I on pituitary and hypothalamus - negative feedback by GH - nervous system (stress, sleep) - metabolites (low glucose stimulates, high glucose inhibits)

Question 44

as you age, GH concentration (increases/decreases)

Answer 44

decreases

Question 45

exercise (stimulates/inhibits) GH

Answer 45

stimulates

Question 46

psychological stress has a (positive/negative) effect on GH

Answer 46

negative