Autonomics IV and V

Question 1

second messenger amplification

Answer 1

all adrenergic receptors have seven membrane spanning helixes and are amplified through various second messenger systems. G proteins increase or decrease cAMP or phosphotidyl inositol hydrolysis

Question 2

termination of action as a transmitter

Answer 2

uptake 1: neuron specific (reuptake)
uptake 2: non-specific, high capacity, followed by metabolism (extra-neuronal)
diffusion

Question 3

modification of chemical transmission by drugs

Answer 3

at each step, pharmacological intervention is possible. synthesis of transmitter, release of transmitter, combining with receptor, termination step.

Question 4

B1 receptor prominent effector organ and effects

Answer 4

heart. increased rate and force of contraction. kidney: renin secretion

Question 5

B2 receptor prominent effector organ and effects

Answer 5

arterioles: dilation. bronchial muscle, pregnant uterus: relaxation. several other sites see increased metabolic effects

Question 6

B3 receptor prominent effector organ and effects

Answer 6

adipose tissue (lipocytes): increased lipolysis and thermogenesis

Question 7

A1 receptor prominent effector organ and effects

Answer 7

arterioles in skin, mucosa, viscera, kidney. veins, uterus, and spleen are all constricted and contracted

Question 8

A2 receptor prominent effector organ and effects

Answer 8

presynaptic nerve endings: inhibit NE release and ACh release in the gut. Postsynaptic in CNS: decreased peripheral sympathetic tone

Question 9

D1 receptor prominent effector organ and effects

Answer 9

renal, mesenteric, and cerebral arterioles: dilation

Question 10

autoreceptor

Answer 10

one neurotransmitter and receptor involved

Question 11

heteroreceptor

Answer 11

more than one receptor/transmitter involved. for example, activation of A2 receptors by NE decreases release of ACh, resulting in relaxation of the gut

Question 12

selectivity

Answer 12

we want to select for maximum desired effects with minimum side effects. we try to learn the specificities of the receptor involved and by designing chemical compounds that selectively activates or blocks that receptor

Question 13

direct adrenergic agonist

Answer 13

“personal” interaction with postsynaptic receptor

Question 14

indirect adrenergic agonist

Answer 14

tyramine and amphetamine. drug causes release of NE, which interacts with the postsynaptic receptor. NE is released from small cytoplasmic pool, not synaptic vesicles

Question 15

mixed adrenergic agonists

Answer 15

partially indirect as well as direct

ephedrine and hydroxyamphetamine

Question 16

dopamine low dose

Answer 16

direct action of DA on DA receptors causes vasodilation, resulting in lower blood pressure and increased urine output

Question 17

dopamine medium dose

Answer 17

more of the same as low dose, but some direct action on B1 receptor in heart and some indirect action/NE release, so positive inotropic effect

Question 18

dopamine high dose

Answer 18

more of medium dose, and some direct action on vascular A1 receptors and indirect action/NE release, thus vasoconstriction

Question 19

fenoldopam

Answer 19

activates D1 receptors only! no A or B action, doesnt cause NE release. acts mainly to increase blood flow at renal, mesenteric, and cerebral arteries to lower blood pressure. short half life, used for hypertensive emergencies

Question 20

Alpha 1 agonists uses

Answer 20

vasoconstrictor. Control hemorrhage (epinephrine), contain local anesthetic (epinephrine), nasal decongestion (ephedrine, phenylephrine), anaphylactic shock (epinephrine), ocular pharmacology, hypotension (dopamine), shock

Question 21

some approaches in treating shock

Answer 21

treatment goal is to increase perfusion of organs. treat with volume, NE, isoproterenol, dopamine, alpha blockers

Question 22

cautions with alpha agonists

Answer 22

localized ischemia may occur at infusion site. avoid extravasation. gradually decrease infusion

Question 23

side effects of alpha adrenergic agonists

Answer 23

hypertension/headache, localized ischemia especially with extravasation, dramatic fall in BP on rapid withdrawal, nervousness, anxiety, and insomnia if they cross the blood brain barrier

Question 24

alpha 2 agonists use

Answer 24

central control of blood pressure (nucleus tractus solitarus) decrease blood pressure by decreasing central sympathetic output

Question 25

beta 1 activation

Answer 25

cardiac stimulation. emergency treatment of cardiac arrest, AV block, congestive heart failure

Question 26

beta 2 activation

Answer 26

smooth muscle relaxation. treatment of bronchial asthma. also relaxes uterine smooth muscle

Question 27

side effects of beta adrenergic agonists

Answer 27

mainly cardiac arrhythmia. direct effect from beta 1 receptor activation. indirect response to lowered BP resulting from B2 receptor mediated vasodilation. occasional skeletal muscle tremor with B2 receptor agonists

Question 28

CNS actions of adrenergic agonists

Answer 28

stimulants to treat narcolepsy and hyperkinesis (ADHD). can be used as anorexics and weight loss (diet aids)

Question 29

uses of beta blockers

Answer 29

hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine, stage fright, heart failure. use only second or third generation B blocker to treat congestive heart failure

Question 30

side effects of beta blockers

Answer 30

too much beta 1: cardiac depression. too much beta 2: bronchoconstriction, may precipitate asthmatic attack. fatigue, nausea, vomiting, diarrhea, sexual dysfunction. do not withdraw abruptly

Question 31

major applications of alpha antagonists

Answer 31

treat hypertension. major side effect is tachycardia and postural hypotension. can treat peripheral vascular disease, raynauds, frostbie, pheochromocytoma, shock, and benign prostatic hyperplasia

Question 32

side effects of sympathetic blocking drugs

Answer 32

postural hypotension, nasal stuffiness, drowsy and dizzy, inhibition of ejactualtion, erectile dysfunction, bradycardia, bronchoconstriction, metabolic alterations