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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
Enzyme system being used and is on intracellular side of membrane
Kinases
26
Which receptor system uses second messenger systems?
Classic cell membrane receptor systems
27
Which receptor system uses kinases?
Catalytic cell membrane receptor systems
28
Coupling molecule used in almost all membrane receptor systems
G-proteins
29
G proteins are active when ___ is bound; inactive when ___ is bound
GTP; GDP
30
Heterotrimeric proteins subunits
Alpha, beta, or gamma
31
T/F: G-proteins are only stimulatory
False - can be stimulatory or inhibitory
32
What second messenger is Phospholipase C associated with?
IP3/Ca2+/DAG
33
What second messenger is adenylyl cyclase associated with?
cAMP
34
What enzyme is IP3/Ca2+/DAG associated with?
Phospholipase C
35
What enzyme is cAMP associated with?
Adenylyl cyclase
36
Adenylyl cyclase system: 1. Hormone binds receptor coupled by a _________
G-protein
37
Adenylyl cyclase system: 1. Hormone binds receptor coupled by a G protein 2. ___ binds G protein and activates ___________
GTP; adenylyl cyclase
38
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 __________
cAMP produced; activates protein kinase A
39
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
Phosphorylated; protein kinase A
40
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
Phosphodiesterase; cAMP
41
What degrades cAMP and shuts down system?
Phosphodiesterase
42
What phosphorylates intracellular proteins?
Protein kinase A
43
What activates protein kinase A?
cAMP
44
What binds G protein to activate adenylyl cyclase?
GTP
45
T/F: Some hormones use multiple hormone receptor systems
True
46
What hormones use the adenylyl cyclase system?
ACTH, FSH, TSH, ADH, Calcitonin, PTH, Glucagon
47
Phospholipase C system 1. Hormone binds receptor coupled by G protein 2. ____ binds G protein and activates __________
GTP; phospholipase C
48
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 ____
DAG and IP3 from PIP2
49
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.
DAG; IP3 activate protein kinase C
50
Protein kinase C
Phosphorylates proteins
51
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.
IP3; Ca2+
52
What causes Ca2+ release from ER or SR stores in phospholipase C system
IP3
53
Hormones using Phospholipase C system
GnRH, TRH, Angiotensin II, ADH, Oxytocin
54
Catalytic receptors on cell surface associated with enzymes on what side
Intracellular side
55
Guanylyl cyclase enzyme steps ___ -> cGMP -> cGMP-dependent kinase -> phosphorylates proteins
GTP
56
Guanylyl cyclase enzyme steps GTP -> ____ -> cGMP-dependent kinase -> phosphorylates proteins
cGMP
57
Guanylyl cyclase enzyme steps GTP -> cGMP -> ______ -> phosphorylates proteins
cGMP dependent kinase
58
Guanylyl cyclase enzyme steps GTP -> cGMP -> cGMP-dependent kinase -> ______ _____
Phosphorylates proteins
59
Serine/threonine kinase systems use either protein kinase
A or C
60
Receptor tyrosine kinases activity occurs where
Within the receptor itself
61
Receptor tyrosine kinases has how many domains
3
62
What are the three domains of the receptor tyrosine kinases?
Extracellular, transmembrane, intracellular
63
In which receptor tyrosine kinases domain does tyrosine kinase activity occur?
Intracellular
64
When hormone binds in receptor tyrosine kinase system, intracellular portion of receptor does what?
Phosphorylates itself
65
In tyrosine kinase-associated receptors, can the intracellular portion phosphorylate itself?
No
66
Receptor type that associate with other proteins that have tyrosine kinase activity
Tyrosine-kinase-associated receptors
67
Guanylyl cyclase enzyme, serine/threonine kinase enzymes/receptor tyrosine kinases/tyrosine kinase-associated receptors are all examples of which receptor system?
Catalytic receptor systems
68
Steroid hormones utilize which receptor system
Intracellular
69
Steroid hormones are ____, which is why they utilize intracellular receptor system
Lipid-based
70
Intracellular receptor systems use which receptors
Cystolic or nuclear receptors
71
In Intracellular receptor systems, cystolic or nuclear receptors initiate
DNA transcription and synthesis of new proteins
72
Intracellular receptor systems: 1. ___________ diffuses across membrane and binds receptor in ____ or _____
Steroid hormone; cytosol or nucleus
73
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 ______________
Dimerizes; steroid-responsive elements
74
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
mRNA; translation

Physiology Exam 3 (13 decks)

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