Unit 2: Autonomic nervous system Flashcards
How many prescribed drugs affect ANS?
More than 50%
Characteristics of a neurotransmitter
synthesized in a presynaptic terminal, stored in vesicle, regulate release into synapse for binding postsynaptic membrane
Pre-ganglionic neurons of parasympathetic
Very long, start in sc end at target organ, release ACH to activate nicotinic receptors
Post-ganglionic neurons of parasympathetic
short, synapse at target organ, release ACH to activate muscarinic receptors
Pre-ganglionic neurons of sympathetic
very short, start in sc and end near sc, release ACH and activate nicotinic receptors
Post-gangliionic neurons of sympathetic
long, end at organ, release norepinephrine to activate adrenergic (a or B) receptors
3 exceptions of post-ganglioinic sympathetic neurons
postga neurons involved with thermoregulation release ACH to work on muscarinic rcts; postga to kidneys release dopamine; prega to adrenal glands synapse directly on adrenal gland: release ACH and activate nicotinic rcts, A glands release epi and activate adrenergic rcts
Acetylcholine released by
preganglionic sympathetic and parasympathetic neuron, postganglionic parasympathetic neurons, adrenal glands, sweat glands, skeletal muscle vasculature
Epinephrine released by
adrenal gland once the sympathetic system has been activated
Norepinephrine released by
postganglionic sympathetic neurons in most end organs
The most often site of pharmacologic manipulation
ganglionic synapse, between pre and post
Strategies for pharmacological intervention
block synthesis and storage, block release, block reuptake, interfere with metabolism, interfere with recognition
Parasympathomimetics
cholinergic, muscarinic agonists
sympathomimetics
adrenergic, adrenergic agonists
Parasympatholytics
anticholinergic, muscarinic antagonists: stops digestion
Parasympatholytics
anticholinergic, muscarinic antagonists: stops digestion
sympatholytics
antiadrenergic, adrenergic antagonists
Nicotinic receptor stimulatory action
binding of ACH is always stimulatory
Muscarinic cholinergic receptor
main receptor at parasympathetic site, mediates secretion and smooth muscle contraction, inhibitory or stimulatory, five subtypes
Muscarinic subtype
M2-found in heart, M3-found in glands and smooth muscle, M1,4,5- found in CNS
Adrenergic receptors
a1, a2, usually stimulatory B1, B2, B3, usually inhibitory except in heart
A1
most blood vessels, contraction of smooth muscle, eye and urinary sphincter
A2
mostly in CNS and target organs, decreases vascular resistance
B1
Found in heart, kidney and brain; increases heart force and contraction, mediates renin
B2
Found in lungs, skeletal muscle vasculature, uterus, mediates s. muscle relaxation
B3
fat cells and lipolysis
Cholinergic effects
DUMBELS; defecation, urination, miosis, bradycardia, emesis, lacrimation, salivation
Anticholinergic effects
Dry as a bone; decreased sweating, decrease salivation, bronchodilation, tachycardia, constipation, urinary retention
Anticholinergic effects
Dry as a bone; decreased sweating, decrease salivation, bronchodilation, tachycardia, constipation, urinary retention
Aqueous humor formed by?
ciliary epithelium, B2
Miosis/mydriasis
Pupil contraction, dilation
Receptor of Circular eye muscles
ACH binds to M3, contraction, antagonists cause dilation
Receptor of radial muscles
Norepinephrine binds to a1, causes contraction of muscle: dilation
Receptor of bladder
B2 causes relaxation, a1-norepi binding causes sphincter contraction; M3 causes relaxation of sphincter
Receptors of heart
ACH/muscarinic receptors agonists decrease heart rate; norepi/ B1 receptors agonists increase hr and contractility
