Midterm 2 - Principles of Hormone Action

Question 1

where are hormones secreted

Answer 1

into blood

Question 2

where do hormones act

Answer 2

at a distance from the release site

Question 3

what do hormones need to be able to do

Answer 3

travel in the blood (solubility)
survive long enough
be active at the target site

Question 4

what do hormones trigger

Answer 4

specific actions in specific target cells

Question 5

what is the requirement for specific recognition

Answer 5

receptors

Question 6

what is the principle of action based on

Answer 6

hormone biochemical structure and properties

Question 7

what are the key to hormone action

Answer 7

receptors

Question 8

what initiate the effects of hormones

Answer 8

the hormones bind to receptors

Question 9

what do lipophilic hormones do

Answer 9

diffuse out of producing cells
circulate mainly bound to carriers in the blood
diffuse in target cells to intracellular receptors

Question 10

what do water-soluble hormones do

Answer 10

they are secreted via exocytosis
they circulate freely in blood
stay out of target cell to surface (extracellular) receptor

Question 11

what are examples of lipophilic hormones

Answer 11

steroid hormones
thyroid hormones

Question 12

are lipophilic hormones soluble in water

Answer 12

no, circulate associated to carrier proteins

Question 13

types of carriers for lipophilic hormones

Answer 13

specific
non specific

Question 14

examples of specific lipophilic hormone carriers

Answer 14

globulins:
CBG
DBG
SHBG
TBG

Question 15

examples of non-specific lipophilic hormone carriers

Answer 15

albumin
pre albumin

Question 16

what are some reasonings for carrier proteins being big

Answer 16

they keep hormones in vessel
prevent hormone degradation

Question 17

does all of a lipophilic hormone get carried

Answer 17

no - a small portion remains free and diffuses to the tissues

Question 18

what is the free lipophilic hormone characteristics

Answer 18

the active portion, but also susceptible to degradation

Question 19

what is the free form (active) lipophilic hormone involved in

Answer 19

feedback loops

Question 20

what does the carrier serve as

Answer 20

hormone reservoir
hormone buffer
hormone protection

Question 21

what do carrier proteins play a major role in

Answer 21

controlling lipophilic hormones

Question 22

in nuclear hormone receptors, what does the ligand binding domain do

Answer 22

binds hormone

Question 23

in nuclear hormone receptors, what does the DNA binding domain do

Answer 23

binds the DNA of target gene

Question 24

in nuclear hormone receptors, what does the activation domain do

Answer 24

stimulates gene transcription

Question 25

in nuclear hormone receptors, what is the orphan receptor

Answer 25

NHR is cloned by no ligand is found

Question 26

what does the action of lipophilic hormones affect

Answer 26

the synthesis of new proteins by gene regulation = slow acting hormones

Question 27

what is the major circulating form of thyroid hormones

Answer 27

T4 (thyroxine)

Question 28

what happens to T4 when it enters the target cell

Answer 28

it is converted to T3 (try-iodo-thryonine)

Question 29

what is the cellular active form of thyroid hormone

Answer 29

T3

Question 30

what does T3 do

Answer 30

binds to its specific receptor after entering the nucleus

Question 31

what happens to hormones after acting

Answer 31

hormones dissociate from the receptor and can be partly degraded in target cells, then go back to circulation and is degraded in the liver

Question 32

can water soluble hormones pass the phospholipid membrane barrier

Answer 32

no

Question 33

how are water soluble hormones secreted

Answer 33

in vesicles by exocytosis

Question 34

how do water soluble hormones circulate

Answer 34

freely

Question 35

what is the water soluble hormone that does not circulate freely (the exception)

Answer 35

IGF-1 circulates bound to carrier

Question 36

what do water soluble hormones bind to

Answer 36

specific receptors on surface of target cell

Question 37

do water soluble hormones enter cell to act

Answer 37

no - need secondary messengers

Question 38

what is the key mediator between hormone and secondary messengers of water soluble hormones

Answer 38

receptor

Question 39

for cell surface receptors, where is the hydrophobic region

Answer 39

hiding in the membrane's phospholipids - transmembrane domain

Question 40

for cell surface receptors, where are hydrophilic regions

Answer 40

outside (extracellular domain) and inside (intracellular domain) cell

Question 41

what activates the intracellular secondary messenger

Answer 41

hormone-receptor

Question 42

for G-protein coupled receptors, what are the messengers

Answer 42

adenylate cyclase (cAMP) Phospholipase C; Ca2+

Question 43

for tyrosine kinase receptor, what is the messenger

Answer 43

auto-phosphorylation

Question 44

for the interleukin/cytokine family of receptors, what is the messenger

Answer 44

JAK-STAT

Question 45

for the Serine kinase (TGFB) family of receptors, what is the messenger

Answer 45

SMADs

Question 46

what do the 3 major types of G-proteins differ by

Answer 46

alpha-subunit

Question 47

what is unique about the tyrosine kinase receptor

Answer 47

there is no need for a second messenger, directly phosphorylates target proteins

Question 48

what are the 3 domains of the tyrosine kinase receptor

Answer 48

transmembrane domain extracellular domain for ligand recognition cytoplasmic domain

Question 49

what does the cytoplasmic domain of the tyrosine kinase receptor have

Answer 49

an autophosphorylation site that transmits regulatory signals and contains ATP binding sites

Question 50

examples of receptors for cytokine

Answer 50

GHwhat wh prolactin erythropoietin interferons interleukins

Question 51

what do cytokine receptors not have

Answer 51

intrinsic kinase activity

Question 52

what is the TGFB family mainly involved in

Answer 52

control of cell proliferation and differentiation

Question 53

what are in the TGFB family

Answer 53

active inhibit MIS

Question 54

what does the cascade of intracellular messenger do

Answer 54

amplifies the signal several thousand times

Question 55

what do the specific effects of cell surface receptors on target cells depend on

Answer 55

the type and amount of messenger activated

Question 56

what are the immediate effects of messenger activation

Answer 56

enzyme activation exocytosis

Question 57

what are the slow effects of messenger activation

Answer 57

stimulation of gene transcription, de novo protein synthesis

Question 58

what happens to the receptor-hormone complex after signalling

Answer 58

it is internalised

Question 59

how is the receptor-hormone complex internalized

Answer 59

fuses to lysosomes and degrades dissociates and receptor is recycled to cell surface

Question 60

why is the receptor-hormone complex internalized

Answer 60

need the termination of message to prevent desensitization