PNS Receptors and Characteristics

Question 1

M1 receptors are located in what tissue?

Answer 1

autonomic ganglia

Question 2

What is the response when M1 receptors are activated?

Answer 2

Depolarizes postsynaptic neurons (slow EPSP)

Question 3

What is the mechanism of M1 receptors?

Answer 3

↑ PLC → ↑ IP3, DAG, Ca++

Question 4

M2 receptors are located in what tissue?

Answer 4

Heart

Axon Terminals

Question 5

What is the response when M2 receptors are activated?

Answer 5

↓ Heart rate, conduction velocity, contractility

Question 6

What is the mechanism of M2 receptors?

Answer 6

↓ AC → ↓ cAMP; ↑ K+ channel efflux, ↓ Ca++ channel influx

Question 7

M3 receptors are located in what tissue?

Answer 7

Smooth muscle, Secretory glands and vascular epithelium

Question 8

What is the response when M3 receptors are activated?

Answer 8

Smooth muscle contraction
Increased secretion of secretory glands
dilates BV

Question 9

What is the mechanism of M3 receptors in the vascular epithelium?

Answer 9

Ca++/CaM activates eNOS → ↑ NO → ↑ cGMP → relaxation

Question 10

Nm receptors are located in what tissue?

Answer 10

Neuromuscular junctions

Question 11

What is the response when Nm receptors are activated?

Answer 11

Skeletal muscle contraction

Question 12

What is the mechanism of Nm receptors?

Answer 12

Opens Na+/K+ channels –> depolarization

Question 13

Nn receptors are located in what tissue?

Answer 13

Autonomic ganglia and Adrenal medulla

Question 14

What is the response when Nn receptors are activated?

Answer 14

Depolarization of postsynaptic neurons (autonomic ganglia)

Depolarization of medullary cells –> secretion of catecholamines (Nn)

Question 15

What is the mechanism of Nm receptors?

Answer 15

Opens Na/K channels –> depolarization

Question 16

What is the mechanism of M3 receptors in smooth muscle and secretory glands?

Answer 16

↑ PLC → ↑ IP3, DAG, Ca++

Question 17

A1 receptors are located in what tissue?

Answer 17

Smooth muscle and liver

Question 18

What is the response when A1 receptors are activated?

Answer 18

Contracts smooth muscle and increases glycogenolysis and gluconeogenesis (liver)

Question 19

What is the mechanism of A1 receptors?

Answer 19

↑ PLC → ↑ IP3, DAG, Ca++

Question 20

A2 receptors are located in what tissue?

Answer 20

Axon terminals
Pancreatic B cells
Vascular smooth muscle
Platelets

Question 21

What is the response when A2 receptors are activated?

Answer 21

↓ NE release (axon terminals)
↓ Insulin release (Pan B cells)
Contraction of smooth muscle
Platelet Aggregation

Question 22

What is the mechanism of A2 receptors?

Answer 22

↓ AC → ↓ cAMP; ↑ K+ channel efflux (via Gβγ); ↓ L- and N-type Ca++ channel influx; ↑ PLC → ↑ IP3, DAG, Ca++

Question 23

B1 receptors are located in what tissue?

Answer 23

Heart and Kidney

Question 24

What is the response when B1 receptors are activated?

Answer 24

↑ Heart rate, conduction velocity, contractility

↑ Renin release

Question 25

What is the mechanism of B1 receptors?

Answer 25

↑ AC → ↑ cAMP → ↑ PKA → ↑ L-type Ca++ channel influx

Question 26

B2 receptors are located in what tissue?

Answer 26

Smooth muscle Heart Liver and skeletal muscle Pancreatic B cells

Question 27

What is the response when B2 receptors are activated?

Answer 27

Relaxes smooth muscle ↑ heart rate contractility ↑ glycogenolysis, gluconeogenesis (liver) ↑ insulin release

Question 28

What is the mechanism of B2 receptors?

Answer 28

↑ AC → ↑ cAMP; in smooth muscle, inhibits MLCK → ↓ myosin-PO4 → relaxation

Question 29

B3 receptors are located in what tissue?

Answer 29

Lipocytes

Question 30

What is the response when B3 receptors are activated?

Answer 30

activates lipolysis

Question 31

What is the mechanism of B3 receptors?

Answer 31

↑ AC → ↑ cAMP

Question 32

D1 receptors are located in what tissue?

Answer 32

Vascular smooth muscle (esp renal)

Question 33

What is the response when D1 receptors are activated?

Answer 33

Dilates blood vessels

Question 34

What is the mechanism of D1 receptors?

Answer 34

↑ AC → ↑ cAMP

Question 35

D2 receptors are located in what tissue?

Answer 35

axon terminals and cholinergic neurons in the gut

Question 36

What is the response when D2 receptors are activated?

Answer 36

↓ DA release | ↓ GI motility

Question 37

What is the mechanism of D2 receptors?

Answer 37

↓ AC → ↓ cAMP; ↑ K+ efflux; ↓ Ca++ influx