Adrenoceptors

Question 1

Which adrenoceptor inhibits sympathetic-associated insulin secretion?

Answer 1

α2

Question 2

Receptors that activate adenylyl cyclase and mechanism

Answer 2

β1,β2, β3, D1.

Activation of adenylyl cyclase, increased cAMP, activation of protein kinases.

Question 3

Imidazoline receptors - effects

Answer 3

Decreased sympathetic outflow from CNS.

Natriuresis.

Question 4

Most potent for β2-adrenoceptors, epinephrine or norepinephrine?

Answer 4

Epinephrine

Question 5

β1-adrenoceptors - effects:

Answer 5

Pos chronotropic (increased HR), inotropic (increased contractility) and dromotropic (increased impulse conduction velocity).
Renin secretion.

Question 6

β2-adrenoceptors - effects:

Answer 6

Smooth muscle relaxation (bronchial, uterine, vascular).
Skeletal muscles: increased K+ uptake.
Activation of glycogenolysis (increased blood glucose).

Question 7

Which adrenoceptor(s) have effects on eyes?

Answer 7

α1: contraction of iris dilator muscle.

α2: Decreased aqueous humor secretion

Question 8

α1-adrenoceptors - mechanism

Answer 8

Phospholipase C activation, increased IP3, Ca2+ release

Question 9

β3-adrenoceptors - effects

Answer 9

Activate lipolysis.
Skeletal muscle: activate thermogenesis.
Utererine relaxation.

Question 10

Which adrenoceptor cause bronchodilation and increased blood glucose?

Answer 10

β2

Question 11

α2-adrenoceptor - mechanism

Answer 11

Inhibition of adenylyl cyclase, decreased cAMP
Feedback inhibition of norepinephrine
Platelet aggregation
insulin secretion inhibition

Question 12

Which adrenoceptor(s) cause exocrine gland secretion?

Answer 12

α1-adrenoceptors

Question 13

D2 receptors - mechanism

Answer 13

Decreased cAMP, increased K currents, decreased Ca influx.

Question 14

Which adrenoceptor(s) activate lipolysis?

Answer 14

β3

Question 15

α1-adrenoceptors - Effects

Answer 15

Smooth muscle (sympathetic neuroeffector junctions): contractions (vascular sm. iris dilator muscle, bladder, urethra, prostate) increases BP.
Exocrine glands: Secretion
CNS: neuronal excitation

Question 16

α2-adrenoceptor - locations and effects

Answer 16

Presynaptic neurons - Feedback inhibition of NE secretion.
Platelets - aggregation.
Pancreas: inhibits insulin secretion (when sympathetic nervous system is activated).
Decreased aqueous humor secretion.
CNS effects.
Other: Adipose, intestinal, hepatic, renal and endocrine tissues.

Question 17

Dopamine receptors - effects:

Answer 17

D1: vascular smooth muscle relaxation.
D2: Activate neurotransmitter release in sympathetic and central nervous systems.

Question 18

Types of adrenoceptors

Answer 18

α1, α2, β1, β2, β3, Dopamine D1 & D2 receptors, Imidazole receptors