L22-24 Alpha and Beta Receptors

Question 1

Function of alpha 1 receptors

Answer 1

Vascular smooth muscle constriction
Contraction of base of bladder, sphincter muscle, and prostate
Mydriasis
Ejaculation

Question 2

Effects of alpha 1 blockade

Answer 2

Decreased peripheral vascular resistance causing dec BP and venous return, orthostatic hypotension
Miosis
Nasal congestion
Easier urine flow from relaxed base of bladder, urethra and prostate
Inhibition of ejaculation

Question 3

Function of alpha 2 receptors

Answer 3

decrease NE release, contract some vascular SmM

Question 4

Effects of alpha 2 blockade

Answer 4

increased NE release, increased sympathetic output, increased BP

Question 5

Functions of beta 1 receptors

Answer 5

inc rate and force of heart contraction
inc automaticity of heart
increase renin secretion

Question 6

Functions of beta 2 receptors

Answer 6

relax bronchioles
dilate some BV’s
increase glycogenolysis
increase production of aqueous humor and intraocular pressure

Question 7

Functions of beta 3 receptors

Answer 7

increase lipolysis

Question 8

How does a dose response curve change with use of a competitive inhibitor?

Answer 8

Shift is usually parallel if acting on same receptor

Question 9

How does a dose response curve change with a non-competitive inhibitor?

Answer 9

Max response is lower, curves not parallel

Question 10

Name the alpha receptor blockers

Answer 10

Reversible: phentolamine, prazosin, terazosin, doxazosin, tamsulosin, alfuzosin, labetalol
Irreversible: phenoxybenzamine
Alpha 2 selective: yohimbine

Question 11

Phentolamine

Answer 11

Competitive alpha 1 and 2 antagonist
Decreases peripheral resistance and BP–especially diastolic
May increase HR
Alpha 2 block increases NE on heart and low BP stimulates baroreceptors
Also stimulates gastric acid secretion