Ch 15 Autonomic Nervous System Flashcards
function of ans
unconscious bodily function
occasionally require instantaneous diversion of energy
how does ans work and are its effectors
innervates smooth, cardiac muscle, and glands (effectors)
operate via unconscious control
SNS vs ANS axons
sns is heavily myelinated and axons extend from cns
ans axons are part of two-neuron chaing (preganglionic is lightly myelinated, postgangionic is not)
what nt is release by sns
acetylcholine
what nt is released by ans
preganglionic fibers release ACh, postganglionic release NE or ACh
sns excitatory or inhibitroy
excitatory
ans excitatory or inhibitory
both
division of ans
sympathetic and parasympathetic
role of sympathetic
mobilized body during extreme situations
e activities - exercise, excitement, emergency, embarassment
role of parasympathetic
performs maintenance activities and conserved body energy
d activities digestion, defecation, diuresis
when sympathetic is in control
HR increases, deep breathing, tachypnea, blood flow to organs reduced and muscles increased, skin cold and sweaty, pupils dilate
when parasympathetic is in control
BP HR RR low, GI tract activity high, skin warm (blood in skin), pupils constricted, diuresis
length of preganglionic nerves and postganglionic nerves
sympathetic - pre short post long
parasympathetic - pre long post short
where do sympathetic neurons exit spinal cord
T1-L2
where do parasympathetic neurons exit spinal cord
cranial 3, 7, 9, 10 and S2-4
ans tone
a system actin g on its own, increased tone means increased activity
sympathetic tone
controls BP
tone goes up, BP rises as blood vessels constrict
tone goes dow, BP lowers as blood vessels dilate
parasympathetic tone and whats important to note
control HR and levels of digestive and urinary system
tone goes up, HR slows
tone goes down, HR rises
sympathetic can override this at any time
cholinergic fibers
ACh relasing
all preganglionic axons
parasympathetic postganglionic axons
may bind to nicotinic or muscarinic receptors
adrenergic fibers
NE releasing fibers
sympathetic postganglionic fibers
may bind to α or β receptors
nicotinic receptors
always excitatory
found on motor end plates
muscarinic receptors
inhibitory or excitatory
slows heart rate and strength of muscle contractions
increases digestive activity
constriction of iris
beta blockers
attach mainly to β adrenergic receptors and lower HR and prevent arrythmias
