Physiology

Question 1

G-protein coupled receptors

Answer 1

7 transmembrane domain associated with G-protein. G-protein has alpha, beta, gamma subunits. Alpha subunit bound to ATP. Once GPCR binds ligand, ATP cleaved releasing G protein to activate second messengers.

Question 2

G-protein coupled receptors associated with Gq

Answer 2

1. “HAVe 1 M and M”
2. H1
3. Alpha 1
4. V1
5. M1
6. M3
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Question 3

G-protein coupled receptors associated with Gs

Answer 3

1. Beta 1
2. Beta 2
3. Beta 3
4. D1
5. H2
6. V2
7. Glucagon
8. PTH
9. TSH
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Question 4

G-protein coupled receptors associated with Gi

Answer 4

1. MAD 2s.
2. M2
3. Alpha 2
4. D2
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Question 5

Cyclic GMP second messenger system

Answer 5

1. Natriuretic peptides- BNP, ANP
2. Nitric oxide
3. G protein stimulates guanylate cyclase (GC)–>turns GTP into cGMP–> activates protein kinase G–> smooth muscle relaxation.
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Question 6

Gi second messenger system

Answer 6

Ligand binds to R–> Gi activation–> decreases AC activity–> ATP not converted into cAMP–> cAMP does not activate PKA–> PKA does not inactivate MLCK allowing for myosin phosphorylation and smooth muscle contraction. PKA does not increase intracellular calcium in heart muscle.

Question 7

Gs second messenger system

Answer 7

Ligand binds to R–> Gs activation–> increases adenylyl cyclase–> turns ATP into cAMP–> cAMP activates Protein Kinase A (PKA). PKA increases intracellular calcium concentrations in the heart. PKA decreases intracellular calcium concentrations in smooth muscle (eg, bronchioles) and inhibits myosin light-chain kinase (thus inhibiting myosin phosphorylation and smooth muscle cell contraction contraction).

Question 8

Gq second messenger system

Answer 8

Ligand binds to R–>Gq activation–>Phospholipase C–> breaks up lipid membrane PIP2 into DAG and IP3. DAG–> Protein Kinase C (PKC). IP3–> liberates intracellular Ca2+ from endoplasmic reticulum–> smooth muscle contraction.

Question 9

Alpha 1 receptor

Answer 9

1. Sympathetic nervous system: Gq
2. Increases vascular smooth muscle contraction (increased SVR)
3. Increased pupillary sphincter muscle contraction (mydriasis)
4. Increased intestinal and bladder sphincter muscle contraction (urinary retention).
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Question 10

Alpha 2 receptor

Answer 10

1. Sympathetic nervous system: Gi
2. Decreased sympathetic (adrenergic outflow)
3. Decreased insulin release
4. Decreased lipolysis
5. Increased platelet aggregation
6. Decreased aqueous humor production
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Question 11

Beta 1 receptor

Answer 11

1. Sympathetic nervous system: Gs
2. Increased heart rate
3. Increased contractility
4. Increased renin release
5. Increased lipolysis
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Question 12

Beta 2 receptor

Answer 12

1. Sympathetic nervous system: Gs
2. Vasodilation
3. Bronchodilation
4. Increased lipolysis
5. Increased insulin release
6. Decreased uterine tone (tocolysis)
7. Ciliary muscle relaxation
8. Increased aqueous humor production
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Question 13

Beta 3 receptor

Answer 13

1. Sympathetic nervous system: Gs
2. Increased lipolysis
3. Increased thermogenesis in skeletal muscle
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Question 14

M1 receptor (muscarininc AChR)

Answer 14

1. Parasympathetic nervous system: Gq
2. CNS
3. Enteric nervous system
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Question 15

M2 receptor (muscarininc AChR)

Answer 15

1. Parasympathetic nervous system: Gi
2. Decreased heart rate
3. Decreased atrial contractility
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Question 16

M3 receptor (muscarininc AChR)

Answer 16

1. Parasympathetic nervous system: Gq
2. Except sweat glands: sympathetic nervous system
3. Increased exocrine gland secretions (eg, lacrimal, sweat, salivary, gastric acid)
4. Increased gut peristalsis
5. Increased bladder contraction
6. Bronchoconstriction
7. Increased pupillary sphincter muscle contraction (miosis)
8. Ciliary muscle contraction (accommodation)
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Question 17

D1 (dopamine) receptor

Answer 17

1. Sympathetic nervous system: Gs
2. Relaxes renal vascular smooth muscle
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Question 18

D2 (dopamine) receptor

Answer 18

1. CNS: Gi
2. Modulates transmitter release, especially in the brain.
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Question 19

H1 (histamine) receptor

Answer 19

1. Gq
2. Increased nasal and bronchial mucus production, increased vascular permeability, contraction of bronchioles, prurities, pain.
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Question 20

H2 (histamine) receptor

Answer 20

1. Gs
2. Increased gastric acid secretion (parietal cells)
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Question 21

V1 (vasopressin) receptor

Answer 21

1. Gq
2. Increased vascular smooth muscle contraction
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Question 22

V2 (vasopressin) receptor

Answer 22

1. Gs
2. Increased H2O permeability and reabsorption in collecting tubules of kidney by increasing aquaporins at membrane.
3. V2 is found in the 2 kidneys.
4. Vasopressin = antidiuretic hormone (ADH)
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