Autonomic Receptors

Question 0

Muscarinic M2

Locations, Responses, Mechanism

Answer 0

Heart
SA node: slowed spontaneous depol; hyperpolarization
AV node: dec conduction velocity
Atrium: dec refractory period, dec contractile force
Ventricle: slight dec in contractility

Mechanism: inhibit AC and inc K channel opening
Hyperpolarization

Question 1

Muscarinic M1

Locations, Responses, Mechanism

Answer 1

Autonomic ganglia: Late excitatory post synaptic potential (EPSP)
CNS: arousal, attention, analgesia

Mechanism: Gq -> PLC -> inc IP3 and DAG -> inc Ca and PKC

Question 2

Muscarinic M3

Location, Response, Mechanism

Answer 2

Smooth muscle: contraction
Secretory glands: secretion

Mechanism: Gq -> PLC -> inc IP3 and DAG -> inc Ca and PKC

Question 3

Nicotinic Nm

Location, Responses, Mechanisms

Answer 3

Skeletal muscle at NMJ: end plate depolarization; skeletal mm contraction

Mechanism: opening of Na/K channels
Transient depolarization

Question 4

Nicotinic Nn

Locations, Responses, Mechanisms

Answer 4

Autonomic ganglia: depolarization and firing of postganglionic neuron
Adrenal medulla: secretion of catecholamines
CNS: arousal, attention, analgesia

Mechanism: opening of Na/K channels
Increase internal Ca

Question 5

Cholinergic receptors are divided into nicotinic and muscarinic Rs.

All ______ receptors are ligand-gated cation-selective channels.
______ receptors are G-protein linked transmembrane receptors.

Answer 5

Nicotinic

Muscarinic

Question 6

Alpha-1 adrenoreceptor

Signaling mediators, tissue, effects

Answer 6

Gq/Gi/Go
Via IP3 & DAG

Vascular smooth muscle: contraction
Genitourinary smooth muscle: contraction
Intestinal smooth muscle: relaxation
Heart: increased inotropy and excitability
Liver: glycogenolysis and gluconeogenesis

Question 7

Alpha-2 adrenoreceptors

Signaling mediators, tissues, effects

Answer 7

Gi/Go
Inhibit AC, activates K channels

Pancreatic beta cells: decrease insulin secretion
Platelets: aggregation
Nerve: decrease NE release
Vascular smooth muscle: contraction

Question 8

Beta-1 receptors

Signaling mediators, tissues, effects

Answer 8

Gs
Activates AC

Heart: increase chronotropy and inotropy, increase AV node conduction velocity
Renal JGA cells: increase renin secretion

Question 9

Beta-2 adrenoreceptors

Signaling mediators, tissues, effects

Answer 9

Gs
Activates AC

Smooth muscle: relaxation
Liver: glycogenolysis and gluconeogenesis
Skeletal muscle: glycogenolysis and K uptake

Question 10

Beta-3 adrenoreceptors

Signaling mediators, tissues, effects

Answer 10

Gs
Activates AC

Adipose: lipolysis

Question 11

All adrenergic receptors are G protein-linked receptors
Rank stimulation by epi, NE, & isoproteronol

Alpha adrenergic
Beta adrenergic

Answer 11

Alpha: epi > NE&raquo_space;> iso

Beta: iso&raquo_space;> epi > NE