ANS Flashcards
ANS General
Controls the body’s involuntary activities. Motor system for visceral organs, blood vessels, and secretory glands.
Oversees the body’s response to immediate lie- threatening challenges and the body’s vital maintenance needs (in: cardiovascular, GI, thermal homeostasis.
Nerves
Bundles of axons of nerve cell, or neuron.
Axon
a nerve fiber; a long projection off o a nerve cell, or neuron.
Ganglia
cluster of nerve cell bodies in peripheral nervous system. synapse depot for nerves.
Afferent
an axon that carries sensory info from periphery to the CNS.`
Efferent
axon that carries motor info from the CNS to the periphery.
Neurotransmitter
endogenous chemicals that relay an action potential from one nerve, across a synapse to a target nerve or organ.
Synapse
a synpatic cleft or space between the presynaptic and postsynaptic endings/effector organ, where the action potential is carried by neurotransmitters.
ANs Anesthesia Concern
Pulmonary, cardio, thermal, endocrine, and GI
Organization of ANS (General)
Preganglionic neuron (1st neuron between cns& ganglia)
- located in hypothalamus, brain stem or spinal cord
- projects to an autonomic ganglia
- Thinly myleinated axon
- ALL release acetylcholine onto nicotinic receptors.
Postganglionic Neurons (2nd neuron goes from ganglia to the effector organ) - unmyelinated axon
ANS Subsystems
Sympathetic Nervous System
- Fight or Flight
- amplification response
Parasympathetic Nervous System
- Rest and Digest
- discrete and narrowly targeted response
Ganglia Difference
Sympathetic Pathway
- close to the spinal cord
- short preganglionic fibers.
- long postganlionic fibers
Parasympathetic Pathway
- ganglia close to/ or in effector organ.
- long preganglionic fibers
- short postganglionic fibers
What is the first neural response?
Acetylcholine
Basal Rate
PsNS and SNS both are “on” at the same time: tone, allows for quick shifting from one to the other, fine control.
Predominant PsNS tone: cilliary muscle, Iris,SA node, GI tract, uterus, bladder, salivary glands.
Predominant SNS: arteriole, veins, sweat glands
Basal Rate
- Most organs have dual innervation (accelerator & brake).
- some patients have exagerrated effects. one or the other
2nd Messenger in ANS
- interaction of neurotransmitters with postsynaptic receptors results in signal transduction.
- in adrenergic (sympathetic) system, trasduction is mediated by G protein, which then regulates adenylyl cyclase, and phospholipase C to generate 2nd meengers and / or directly modulate various ion channels.
SYN 3 types of nerve fibers
- Grouped as paired sympathetic chains (2 sets)
- Various unpaired distal plexuses (group of nerves)
- terminal or collateral ganglia near the target.
largest segment comes from the Thoracic
What is a Plexuses
A bundle of nerves
SNS response to internal or external challenges
- fight or flight
- increase heart rate, arterial pressure, and cardiac output; dilate the bronchial tree; and shunt blood away from intestine and other viscera to voluntary muscles.