ch 7 peripheral nervous system efferent division

PNS efferent divsion

how cns controls activites of muscles and glands

autonomic nervous system

involuntary branch of pns, innervates cardiac, smooth, exocrine glands, endocrine glnads, adipose tissue

PNS efferent divsion

how cns controls activites of muscles and glands

autonomic nervous system

involuntary branch of pns, innervates cardiac, smooth, exocrine glands, endocrine glnads, adipose tissue

Somatic nervous system

voluntary control, skeletal muscle

autonomic nerve pathway

from cns to innervated organ, 2 neuron chain- preganglionic fiber(wynapses w cell body of second neuron), postganglionic fiber(innervates effector organ)

sympathetic nervous system

fibers originate in thoracic and lumbar, short preganglionic fibers that release ach, long postganglionic fibers that release norepinepherine,

parasympathetic nervous system

fibers originate from cranial and sacral areas of cns, long preganglionic fibers that release ach, short postganglionic fibers that release ach,

Adrenal Medulla

modified part of smpathetic nervous system, modified sympathetic ganglion that does not give rise to post ganglionic fibers, stim of preganglionic fibers prompts secretion fo horomones into the blood

Cholineric receptors

bind to Ach

nicotinic receptors

found on postganglionic cell bodies of all autonomic ganglia

muscarinic receptors

effector cell membranes

Andrenergic receptors

bind to norepinephrine and epinephrine, alpha and beta receptors

Agonists

binds to same receptor as neurotransmitter, ellicit an effect that mimics tha of neurotransmitter,

antagonist

bind w receptor and block neurotransmitter's response

Somatic nervous system axons

axons of motor neurons that originate in spinal cord or brain stem and end on skeletal muslce, motor neurons release ach that stimulates muscle contraction

Neuromuscular junction

axon terminal of motor neuron forms this with a single muscle cell, signals passed bw by using Ach, released Ach binds to receptor sites on motor end plate of muscle cell membrane- triggers opening of specific channels in motor end plate, ion movements depolarize motor end plate, producing end-plate potential, local current flows between depolarized end plate and adjacent muscle membrane brings adjacent areas to threshold, action potential is initiated and propagated throughout muscle fiber

Acetylcholinesterase

inactivates Ach, ends end plate potential and the action potential and resultant contraction

Black widow spider venom

causes explosive release of Ach

botulism

blocks release of Ach

Curare

blacks action of Ach at receptor sites

organophosphates

prevents inactivation of ach

myasthenia gravis

inactivates Ach receptor sites