Midterm 2 - Principles of Hormone Action Flashcards

1
Q

where are hormones secreted

A

into blood

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2
Q

where do hormones act

A

at a distance from the release site

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3
Q

what do hormones need to be able to do

A

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

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4
Q

what do hormones trigger

A

specific actions in specific target cells

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5
Q

what is the requirement for specific recognition

A

receptors

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6
Q

what is the principle of action based on

A

hormone biochemical structure and properties

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7
Q

what are the key to hormone action

A

receptors

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8
Q

what initiate the effects of hormones

A

the hormones bind to receptors

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9
Q

what do lipophilic hormones do

A

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

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10
Q

what do water-soluble hormones do

A

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

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11
Q

what are examples of lipophilic hormones

A

steroid hormones
thyroid hormones

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12
Q

are lipophilic hormones soluble in water

A

no, circulate associated to carrier proteins

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13
Q

types of carriers for lipophilic hormones

A

specific
non specific

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14
Q

examples of specific lipophilic hormone carriers

A

globulins:
CBG
DBG
SHBG
TBG

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15
Q

examples of non-specific lipophilic hormone carriers

A

albumin
pre albumin

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16
Q

what are some reasonings for carrier proteins being big

A

they keep hormones in vessel
prevent hormone degradation

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17
Q

does all of a lipophilic hormone get carried

A

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

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18
Q

what is the free lipophilic hormone characteristics

A

the active portion, but also susceptible to degradation

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19
Q

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

A

feedback loops

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20
Q

what does the carrier serve as

A

hormone reservoir
hormone buffer
hormone protection

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21
Q

what do carrier proteins play a major role in

A

controlling lipophilic hormones

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22
Q

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

A

binds hormone

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23
Q

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

A

binds the DNA of target gene

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24
Q

in nuclear hormone receptors, what does the activation domain do

A

stimulates gene transcription

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25
Q

in nuclear hormone receptors, what is the orphan receptor

A

NHR is cloned by no ligand is found

26
Q

what does the action of lipophilic hormones affect

A

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

27
Q

what is the major circulating form of thyroid hormones

A

T4 (thyroxine)

28
Q

what happens to T4 when it enters the target cell

A

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

29
Q

what is the cellular active form of thyroid hormone

A

T3

30
Q

what does T3 do

A

binds to its specific receptor after entering the nucleus

31
Q

what happens to hormones after acting

A

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

32
Q

can water soluble hormones pass the phospholipid membrane barrier

A

no

33
Q

how are water soluble hormones secreted

A

in vesicles by exocytosis

34
Q

how do water soluble hormones circulate

A

freely

35
Q

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

A

IGF-1 circulates bound to carrier

36
Q

what do water soluble hormones bind to

A

specific receptors on surface of target cell

37
Q

do water soluble hormones enter cell to act

A

no - need secondary messengers

38
Q

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

A

receptor

39
Q

for cell surface receptors, where is the hydrophobic region

A

hiding in the membrane’s phospholipids - transmembrane domain

40
Q

for cell surface receptors, where are hydrophilic regions

A

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

41
Q

what activates the intracellular secondary messenger

A

hormone-receptor

42
Q

for G-protein coupled receptors, what are the messengers

A

adenylate cyclase (cAMP)
Phospholipase C; Ca2+

43
Q

for tyrosine kinase receptor, what is the messenger

A

auto-phosphorylation

44
Q

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

A

JAK-STAT

45
Q

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

A

SMADs

46
Q

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

A

alpha-subunit

47
Q

what is unique about the tyrosine kinase receptor

A

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

48
Q

what are the 3 domains of the tyrosine kinase receptor

A

transmembrane domain
extracellular domain for ligand recognition
cytoplasmic domain

49
Q

what does the cytoplasmic domain of the tyrosine kinase receptor have

A

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

50
Q

examples of receptors for cytokine

A

GHwhat wh
prolactin
erythropoietin
interferons
interleukins

51
Q

what do cytokine receptors not have

A

intrinsic kinase activity

52
Q

what is the TGFB family mainly involved in

A

control of cell proliferation and differentiation

53
Q

what are in the TGFB family

A

active
inhibit
MIS

54
Q

what does the cascade of intracellular messenger do

A

amplifies the signal several thousand times

55
Q

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

A

the type and amount of messenger activated

56
Q

what are the immediate effects of messenger activation

A

enzyme activation
exocytosis

57
Q

what are the slow effects of messenger activation

A

stimulation of gene transcription, de novo protein synthesis

58
Q

what happens to the receptor-hormone complex after signalling

A

it is internalised

59
Q

how is the receptor-hormone complex internalized

A

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

60
Q

why is the receptor-hormone complex internalized

A

need the termination of message to prevent desensitization