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Physiology Exam 3 > Lecture 14: Mechanism of Hormone Action and Second Messengers > Flashcards

Lecture 14: Mechanism of Hormone Action and Second Messengers Flashcards

1
Q

Threshold response

A

Minimal concentration of hormone needed to elicit measurable response

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2
Q

Final outcome of interaction of hormone and target cells depends on…

A

Hormone concentration
Receptor number
Affinity of hormone for receptor
Duration of exposure to hormone
Intracellular factors - enzymes, cofactors

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3
Q

Responsiveness is expressed in

A

Dose-response relationship

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4
Q

Magnitude of response correlated with

A

Hormone concentration (as concentration of hormone increases, response increases)

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5
Q

Maximum response

A

A further increase in hormone will elicit no more response

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6
Q

Decrease in responsiveness caused by:

A

Decrease in # target cells or total receptors/cell
Concentration of enzymes activated by hormone

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7
Q

Sensitivity

A

The concentration of hormone producing 50% maximal response

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8
Q

Two ways sensitivity can be changed

A

Changing number of receptors or affinity receptors

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9
Q

If more hormone is required to get a 50% response, then sensitivity

A

Decreased

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10
Q

If less hormone is required to get a 50% response, then sensitivity

A

Increased

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11
Q

Decreasing sensitivity =

A

Down-regulation of receptors

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12
Q

When hormone concentrations high (in respect to sensitivity), what happens

A

Either number or affinity of receptors decreases

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13
Q

Increasing sensitivity =

A

Up-regulation of receptors

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14
Q

When hormone concentrations low (in respect to sensitivity), what happens

A

Either number of affinity of receptors increases

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15
Q

General mechanism of hormone action
1. Hormone is recognized and binds to a ______ ______

A

Membrane receptor

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16
Q

General mechanism of hormone action
1. Hormone is recognized and binds to a membrane receptor –> ________________

A

Hormone-receptor complex

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17
Q

General mechanism of hormone action
1. Hormone is recognized and binds to a membrane receptor –> Hormone-receptor complex
2. Hormone-receptor complex either coupled to a ________________ OR must act ________

A

signal-generating mechanism OR must act as one itself

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18
Q

General mechanism of hormone action
1. Hormone is recognized and binds to a membrane receptor –> Hormone-receptor complex
2. Hormone-receptor complex either coupled to a signal-generating mechanism OR must act as one itself
3. Generated signal (______ ______) affects __________ _______ by.. (will be different card)

A

Second messenger; intracellular process

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19
Q

General mechanism of hormone action
1. Hormone is recognized and binds to a membrane receptor –> Hormone-receptor complex
2. Hormone-receptor complex either coupled to a signal-generating mechanism OR must act as one itself
3. Generated signal (second messenger) affects intracellular process by _______ OR _______________

A

altering activity; OR concentration of functional or structural proteins

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20
Q

Hormone receptor systems are located either on

A

Cell membrane or within cell

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21
Q

Which receptor location produces a very rapid response?

A

Cell membrane

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22
Q

Classified according to membrane receptor structure OR second messenger system used (usually fast response)

A

Classic cell membrane receptor system

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23
Q

Doesn’t use second messenger system, but rather an enzyme system such as kinases (usually rapid response)

A

Catalytic cell membrane receptor system

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24
Q

Uses cytoplasmic or nuclear receptors (usually a slow response - hours)

A

Intracellular receptor system

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25
Q

Enzyme system being used and is on intracellular side of membrane

A

Kinases

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26
Q

Which receptor system uses second messenger systems?

A

Classic cell membrane receptor systems

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27
Q

Which receptor system uses kinases?

A

Catalytic cell membrane receptor systems

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28
Q

Coupling molecule used in almost all membrane receptor systems

A

G-proteins

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29
Q

G proteins are active when ___ is bound; inactive when ___ is bound

A

GTP; GDP

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30
Q

Heterotrimeric proteins subunits

A

Alpha, beta, or gamma

31
Q

T/F: G-proteins are only stimulatory

A

False - can be stimulatory or inhibitory

32
Q

What second messenger is Phospholipase C associated with?

A

IP3/Ca2+/DAG

33
Q

What second messenger is adenylyl cyclase associated with?

A

cAMP

34
Q

What enzyme is IP3/Ca2+/DAG associated with?

A

Phospholipase C

35
Q

What enzyme is cAMP associated with?

A

Adenylyl cyclase

36
Q

Adenylyl cyclase system:
1. Hormone binds receptor coupled by a _________

A

G-protein

37
Q

Adenylyl cyclase system:
1. Hormone binds receptor coupled by a G protein
2. ___ binds G protein and activates ___________

A

GTP; adenylyl cyclase

38
Q

Adenylyl cyclase system:
1. Hormone binds receptor coupled by a G protein
2. GTP binds G protein and activates adenylyl cycalse
3. ____ produced and activates __________

A

cAMP produced; activates protein kinase A

39
Q

Adenylyl cyclase system:
1. Hormone binds receptor coupled by a G protein
2. GTP binds G protein and activates adenylyl cycalse
3. cAMP produced and activates protein kinase A
4. Intracellular proteins ________ by ______, causing physiologic actions

A

Phosphorylated; protein kinase A

40
Q

Adenylyl cyclase system:
1. Hormone binds receptor coupled by a G protein
2. GTP binds G protein and activates adenylyl cycalse
3. cAMP produced and activates protein kinase A
4. Intracellular proteins phosphorylated by protein kinase A causing physiologic actions
5. ____________ degrades _____, shutting system down

A

Phosphodiesterase; cAMP

41
Q

What degrades cAMP and shuts down system?

A

Phosphodiesterase

42
Q

What phosphorylates intracellular proteins?

A

Protein kinase A

43
Q

What activates protein kinase A?

A

cAMP

44
Q

What binds G protein to activate adenylyl cyclase?

A

GTP

45
Q

T/F: Some hormones use multiple hormone receptor systems

A

True

46
Q

What hormones use the adenylyl cyclase system?

A

ACTH, FSH, TSH, ADH, Calcitonin, PTH, Glucagon

47
Q

Phospholipase C system
1. Hormone binds receptor coupled by G protein
2. ____ binds G protein and activates __________

A

GTP; phospholipase C

48
Q

Phospholipase C system
1. Hormone binds receptor coupled by G protein
2. GTP binds G protein and activates phospholipase C
3. Phospholipase C liberates ______ and ____ from ____

A

DAG and IP3 from PIP2

49
Q

Phospholipase C system
1. Hormone binds receptor coupled by G protein
2. GTP binds G protein and activates phospholipase C
3. Phospholipase C liberates DAG and IP3 from PIP2
4. IP3 causes Ca2+ release from ER or SR stores.
5. ___ and ___ activate __________ which phosphorylates proteins.

A

DAG; IP3 activate protein kinase C

50
Q

Protein kinase C

A

Phosphorylates proteins

51
Q

Phospholipase C system
1. Hormone binds receptor coupled by G protein
2. GTP binds G protein and activates phospholipase C
3. Phospholipase C liberates DAG and IP3 from PIP2
4. ____ causes ____ release from ER or SR stores.

A

IP3; Ca2+

52
Q

What causes Ca2+ release from ER or SR stores in phospholipase C system

A

IP3

53
Q

Hormones using Phospholipase C system

A

GnRH, TRH, Angiotensin II, ADH, Oxytocin

54
Q

Catalytic receptors on cell surface associated with enzymes on what side

A

Intracellular side

55
Q

Guanylyl cyclase enzyme steps
___ -> cGMP -> cGMP-dependent kinase -> phosphorylates proteins

A

GTP

56
Q

Guanylyl cyclase enzyme steps
GTP -> ____ -> cGMP-dependent kinase -> phosphorylates proteins

A

cGMP

57
Q

Guanylyl cyclase enzyme steps
GTP -> cGMP -> ______ -> phosphorylates proteins

A

cGMP dependent kinase

58
Q

Guanylyl cyclase enzyme steps
GTP -> cGMP -> cGMP-dependent kinase -> ______ _____

A

Phosphorylates proteins

59
Q

Serine/threonine kinase systems use either protein kinase

A

A or C

60
Q

Receptor tyrosine kinases activity occurs where

A

Within the receptor itself

61
Q

Receptor tyrosine kinases has how many domains

A

3

62
Q

What are the three domains of the receptor tyrosine kinases?

A

Extracellular, transmembrane, intracellular

63
Q

In which receptor tyrosine kinases domain does tyrosine kinase activity occur?

A

Intracellular

64
Q

When hormone binds in receptor tyrosine kinase system, intracellular portion of receptor does what?

A

Phosphorylates itself

65
Q

In tyrosine kinase-associated receptors, can the intracellular portion phosphorylate itself?

A

No

66
Q

Receptor type that associate with other proteins that have tyrosine kinase activity

A

Tyrosine-kinase-associated receptors

67
Q

Guanylyl cyclase enzyme, serine/threonine kinase enzymes/receptor tyrosine kinases/tyrosine kinase-associated receptors are all examples of which receptor system?

A

Catalytic receptor systems

68
Q

Steroid hormones utilize which receptor system

A

Intracellular

69
Q

Steroid hormones are ____, which is why they utilize intracellular receptor system

A

Lipid-based

70
Q

Intracellular receptor systems use which receptors

A

Cystolic or nuclear receptors

71
Q

In Intracellular receptor systems, cystolic or nuclear receptors initiate

A

DNA transcription and synthesis of new proteins

72
Q

Intracellular receptor systems:
1. ___________ diffuses across membrane and binds receptor in ____ or _____

A

Steroid hormone; cytosol or nucleus

73
Q

Intracellular receptor systems:
1. Steroid hormones diffuses across membrane and binds receptor in cytosol or nucleus
2. Receptor undergoes conformational change, complex ______ and binds to ______________

A

Dimerizes; steroid-responsive elements

74
Q

Intracellular receptor systems:
1. Steroid hormones diffuses across membrane and binds receptor in cytosol or nucleus
2. Receptor undergoes conformational change, complex dimerizes and binds to steroid-responsive elements
3. Complex is now a transcription factor - ____ transcribed, _____ occurs, new proteins, physiologic action

A

mRNA; translation

Physiology Exam 3 (13 decks)

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