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Flashcards in Physiology Deck (22)
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1

G-protein coupled receptors

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.

2

G-protein coupled receptors associated with Gq

1. "HAVe 1 M and M"
2. H1
3. Alpha 1
4. V1
5. M1
6. M3
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3

G-protein coupled receptors associated with Gs

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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4

G-protein coupled receptors associated with Gi

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

Cyclic GMP second messenger system

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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6

Gi second messenger system

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.

7

Gs second messenger system

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).

8

Gq second messenger system

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.

9

Alpha 1 receptor

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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10

Alpha 2 receptor

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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11

Beta 1 receptor

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

Beta 2 receptor

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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13

Beta 3 receptor

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

M1 receptor (muscarininc AChR)

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

M2 receptor (muscarininc AChR)

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

M3 receptor (muscarininc AChR)

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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17

D1 (dopamine) receptor

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

D2 (dopamine) receptor

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

H1 (histamine) receptor

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

H2 (histamine) receptor

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

V1 (vasopressin) receptor

1. Gq
2. Increased vascular smooth muscle contraction
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22

V2 (vasopressin) receptor

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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