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.
pathways that synapse with collateral ganglia
pregang from T5 to L2 synapse w collateral ganglia, form sphlanic nerves (greater, lesser, least, lumber and sacral) and all serve abdominal viscera.
pathways to abdomen that synapse with collateral ganglia
fibers T5 to L2 innervate abdomen, to serve stomach, spleen, most intestines, kidneys
pathways to pelvis that synapse with collateral ganglia
T10 to L2 innervate pelvis, serves bladder reproductive organs, and other part large intenstine.
effect of sympathetic division on abdominiopelvic viscera?
inhibitory
5 components of visceral reflex arcs
receptor in viscera, sensory neurons (non encapsulated nerve endings that send sensory info about chemical changes and stuff happening in viscera), integration center, motor neurons (pregang and postgang neurons), and visceral effector (smooth muscle, cardiac muscle, glands)
ANS neurotrans
ACh (acetylcholine)n is not entirely inhiboroty or excitatory, dpeendson receptor it binds to! some fibers releases some type may be IPSP some others may be EPSP
cholinergic fibers
release ACh at ALL ANS pregang axons and ALL parasympathetic postgang axons at synapse with effector organ. These fibers are in any fiber that releases or produces ACh
nicotinic receptors
found on all postgang neurons (sympathetic and para), they produce hormones of adrenal medulla and sarcolemma of skeletal muscle. ACH BIND HERE ALWAYS STIMULATES
sarcolemma of skeletal muscle cells
not autonomic. bind to ACh
MUscarinic receptors
ALL parasympathetic effectors and some sympathetic effectors. can be stimulatory or inhibitory. (ACH TO HEART IS INHINBITORY, REST HR, ACH TO MUSCARINIC IS STIMULATORY IN GASTRO)
norepinephrine (NE)
in sympathetic, not entirely inhibit or excite, depends on receptor. released by adrenergic fibers at sympathetic postganglionic axons. adrenaline rush!
NE adrenergic receptors
alpha and beta
alpha is in all sympathetic organs
beta is in heart, adipose, kidney, lungs, blood vessels
is NE binding stimulatory or inhibitory
its both! ex: at heart can have beta increase activityVS beta at bronchioles causing dilation.
sympathetic and parasympathetic division EFFECTS
most organs have dual innervation, so impulses can be sent at the same time.
sympathetic and para division interaction
OPPOSITE effects, whatever is more rapidly sent will win. Organ gets both message and in order to not get confused just takes quickest one.
increased sympathetic activity leads to…
increased HR and BP, dilated airways, digestion n poop decrease, pupils dilate, reproduction decrease. these effects important for fight or flight bc inhibits visceral organs in abdominopelvic area, so that other things can be more necessary
increased parasympathetic aciitivty….
resting HR, decreased airway diameter, increased digestion and poop, constricts pupils, reproduction increase. GOOD FOR REST N DIGEST BC abdomiopelvic organs are not as necessary
vasomotor, or sympathetic tone
continuous partial blood vessel constriction.
why is partial constriction in muscle tone important
we need muscle tissue to constrict a little even wheat rest or can lose ability to contract
sympathetic fibers…
control blood vessel diameter and supply
BP Low,
vasomotor fibers fire rapidly., vessels dilate. Dilation MAKES IT wider SO SAYS WHERE DOES BLOOD GO
BP high,
vasomotor fibers fire less rapidly, muscle relaxes and vessels dilate, DILATION MAKES IT WIDER SO BP HIGH bc more fluid can come
parasympathetic tone
consistent, always there, but sympathetic can overtake it. in cardiac muscle tissue mostly, and smooth muscle of digest and urine organs .
effect o f parasympathetic tone
slows HR, maintains normal activity of digestive and urinary organs - no effect one blood flow just visceral tissue
unique roles in sympathetic division
since it innervates more superficial body parts, it can have thermoregulatory heat response, Renin kidney release, and metabolic changes
thermoreg response to heat
warm blood close to skin regulates body heat, blood vessels will dilate in heat but constrict in cold. sweat glands activate in heat
renin in kidneys release
BP incereased from vasomotor activity
metabolic changes effects
increases metabolic cell rate, raises blood glucose levels (which is used for ATP), mobilizes fats used fuel use., relies on fatty acids for help.
localized vs diffuse
parasympathetic is localized, sympathetic is diffuse.
parasympathetic localization- how?
very specific, short lived control by using pregang neuron synapse with 1 or more postgang. then, parasympathetic fibers will release ACh and get broken down by ACherase- SHORT LIVED CONTROL OVER EFFECTOR ORGANS
sympathetic diffuse, how?
diffuse long lasting control, pregang synapse with multiple postgang and NE and epinephrine prolong the effects of it. NO ENZYME ERASES THE ACTIVATION HERE, ONE PREGANG FIBER CAN DO A LOT TO MULTIPLE ORGANS
CONTROL OF ANS
hypothalamus controls most visceral organs
anterior and posterior hypothalamus areas
anterior: parasympathetic division
posterior: sympathetic division
coordinates heart, bp, temp, water balance, endocrine activity
limbic system and hypothalamus interaction
relays output through hypothalamus, emotional reactions occur due to fear or danger or stress and activates sympathetic
hypertension
high BP, overactive vasoconstrictor. too much vasomotor. heart works harder to get blood thru small vessels.
hypertension treatment
adrenergic receptor blocking drugs. it can lead to heart disease, enlarged arteries, or even kidney failure.
raynauds disease
much vasoconstriction due to cold or emotional stress. skin of phalanges becomes pale. even can get cyanotic, bc cells lack O2
autonomic dysreflexia
an abnormal reflex. in quadriplegic individuals (spinal cord issueABOVE T6). caused by uncontrolled autonomic neurons, can even happen bc pain to skin or overfilled visceral organ
