ch 14- autonomic nervous system Flashcards
43 slides
somatic nervous system (SNS)
system responsible for voluntary muscle movements, and somatic reflex arcs
autonomic nervous system (ANS)
basically all effectors are visceral, we don’t control that. helps maintain stable environment (like HR, BP, pupil size, body temp, or increase/decrease stomach secretions)
PNS divisions
sensory afferent division & motor efferent division. motor has somatic and ANS! ANS has sympathetic and parasympathetic
ANS and SNS effector organs
SNS: skeletal muscle tissue
ANS: cardiac muscle tissue, smooth muscle (in gut), and glands
efferent pathways and ganglia of SNS
single neuron extends from CNS to effector. motor neuron cell bodies located in CNS, then axons in PNS extend to skeletal muscle.
efferent pathways and ganglia of ANS
2 neuron chain to reach effector, preganglionic neuron is cell body in CNS and axon extends to effector organ. postgangliotic neuron is cell body outside CNS, Avon extends to effector organ. ganglia is site of synapse between preganglion and postganglion.
SNS to PNS
one neuron from CNS to effector organs, with a heavily myelinated axon. releases ACL, acetylcholine and is always excitatory. ACL has a stimulatory effect on muscle contraction!
sympathetic ANS to PNS
2 neuron chain, lightly myelinated preganglionic axons to ganglion then nonmyelinated postganglionic. ACH can release IPSP or EPSP depending on if norepinephrine has beta or alpha from the adrenerguc receptors
parasympathetic ANS to PNS
lightly myelinated preganglionic axon to ganglion to nonmyekinated postganglionic axon.
parasympathetic division of ANS
rest and digest- low energy. does housekeeping of digestion/waste elimination, as well as HR, BP, airway diameter, pupil, and reproduction. fibers are in brain/spinal cord, and can be long (preganglionic) or short (postganglionic)- ganglia is on or near effector organ
parasympathetic ANS cranial portion
supplies parasympathetuc fibers to head, neck, and thoracic and abdominal regions. preganglionic runs in oculomotor and facial as well as glossopharyngeal and vagus nerves.
oculomotor nerve
innervates smooth muscle in eyes and lens. allows eye movement, and smooth muscle controls pupil size. lens will bulge with influence of parasympathetic nerve.
facial nerve
stimulates large head glands, like 2/3 salivary nasal and lacrimal.
glossopharyngeal nerve
activates parotid salivary gland, the 1/3 left from facial, for saliva production. largest gland in salivary conduction
vagus nerve
fibers to neck and almost every thoracic and abdominal organ! only one that goes past head and neck.
cardiac plexus: fibers to heart, slower when sitting
pulmonary plexus: lung fibers, diameter or airways depending on intake of air.
esophageal plexus: innervates liver, gallbladder, stomach, etc for digestion.
each plexus increases activity.
sacral portion of parasympathetic ANS
pelvic splanchnic nerves, which serve pelvic prgans and distal large intestine. pee and cum stimulated here.
sympathetic division of ANS
What lumbar region, what length is pre n post gang, where is ganglia n why
fight or flight, when we are scared/excited/embarrassed. it mobilizes body for HR and BP change, and makes energy at higher expedenture. fibers originate at thoracolumbar region, T1 to L2. HERE pregang is short, postgang is long. ganglia is closer to spinal cord. that is bc its more near complex organ to do complex stuff.
sympathetic division is more what than parasympathetic
much more complex. innervates smooth muscle, cardiac muscle, and body cavity glands. it also innervates smooth glands n muscles in superficial regions.
sympathetic trunk
pregangg fibers leave spinal cored to form it. allows the pregangg axons to travel to spinal nerves higher or lower than original area. blood can flow to more muscles that need it. trunk is on both sides of spinal cord. allows up n down travel.
pathway to sympathetic trunk
pregangg exits spinal cord, fibers pass through WHITE RAMUS COMMUNICANS (guides pregangg to sympathetic trunk) and then fibers can enter the SYMPATHETIC TRUNK GANGLION (where prrgangg synapse w post ganggg)
3 different synapse ways at trunk ganglion
1- they can synapse at same level (pre n post ganglionic neurons I mean)
2- they can synapse at higher or lower levels
3- they can synapse at a distant collateral ganglion in abdomen and pelvis. so here, would not synapse at effector organ, rather at the collateral ganglion.
what happens if synapse forms in trunk ganglia?
posting can fiber through dorsal ramming communicans to enter ventral or dorsal ramps of adjoining spinal nerve.
gray ramii communicans
carry postgang from sympathetic trunk ganglion to periphery, allows it to leave trunk to effectors
pathway to head through trunk ganglia
pregang emerge from T1-T4 with postgang at superior cervicall ganglion (still postgang) or sympathetic trunk.
this will serve skin and blood vessels of the head, stimulate dilator eye muscles, inhibit nasal or salivary glands, innervates upper eyelid muscle, and heart.
pathway to thorax in trunk ganglia
pregang fibers emerge from T1-T6, which saves space bc they r bundled together. most postgang axons pass through cardiac and pulmonary and esophagus plexuses to effector organ.