Autonomic Nervous System Flashcards
what are the divisions of the ANS?
sympathetic and parasympathetic divisions
what is the role of the ANS?
homeostasis
reproduction
regulates viscera, vasculature, and glands
what are the ANS receptors?
mechanoreceptors (pressure and stretch)
- pressure receptors: aorta, carotid sinus, lungs
- stretch receptors: veins, bladder, intestines
chemoreceptors (chemical changes)
- carotid and aortic bodies: oxygen
- medulla: H+ and CO2 (breathing)
- hypothalamus: plasma glucose, electrolytes
thermoreceptors (temp changes)
- hypothalamus: internal temp
- cutaneous receptors: external temp
nociceptors (pain)
- viscera, arterial walls
what are the afferent pathways of the ANS?
dorsal roots to SC
CN 9 and 10 to BS
afferent pathways from dorsal roots to SC
from muscles, vessels, or intestines to SC
afferent pathways from CN 9, 10 to BS
only CNs transmitting info from viscera to brain
CN 9: info from larynx and pharynx
CN 10: info from aortic arch, bronchii, and liver
what do the visceral afferents entering the BS via CNs go through?
the solitary nucleus
what is the solitary nucleus?
the main visceral sensory nucleus in the brain
from the solitary nucleus, what 2 areas can the visceral afferents be conveyed to?
visceral control area
regulatory area
what is the visceral control area?
in the medulla and pons
direct control of vital functions
what is the regulatory area?
in hypothalamus and limbic system
emotions and motivation
no direct control over vital functions, but can modulate them
what do the visceral afferents connect to?
visceral controls area
regulatory area
visceral (sympathetic) efferents
what additional areas do nociceptive afferents connect to?
somatosensory nociceptive tracts (contributing to referred pain)
somatic efferents (muscle guarding)
what is referred pain?
pain felt at a site different from the injured organ/body part
what is central regulation of autonomic function? what contributes to it?
efferents of the ANS
hypothalamus
medulla
pons
what is the role of the hypothalamus in central regulation of autonomic function?
sympathetic and parasympathetic headquarters
master controller of homeostasis
hypothalamospinal and hypothalamobulbar tracts
direct action on pons and medulla
what is the role of the medulla in central regulation of autonomic function?
processing center for complex visceral reflexes (sympathetic and parasympathetic)
HR, respiration, vasoconstriction/dilation via autonomic efferents and vagus nerve
coughing, swallowing, vasomotor, and cardiac centers
what is the role of the pons in central regulation of autonomic function?
respiration
what is the role of the limbic system with the thalamus?
emotions and sensory input
- anxious=increased HR
- embarrassed=blushing
what is integration of central and peripheral receptor info for autonomic regulation?
checks and balances on ANS changes like respiration
ex: central and peripheral chemoreceptors adjust respiration when medulla detects CO2 and pH of blood
- high CO2, low pH=increased respiration and depth
what are the 2 main CNS outputs? (efferents)
somatic motor: skeletal muscle
autonomic: everything else
somatic motor division of the CNS output
skeletal muscles
voluntary/conscious
1 neuron system
autonomic division of the CNS output
everything else that isn’t skeletal muscle
usually 2 neurons system (1 exception)
hormonal influence
nonconscious
what are the 2 efferent divisions of the ANS?
sympathetic and parasympathetic
what is the sympathetic division?
fight or flight
adrenergic (E, NE)
thoraco-lumbar efferent (T1-L2)
what is the parasympathetic division of the ANS?
rest and digest
cholinergic (ACh)
cranio-sacral efferents
what is the 2 neuron system?
CNS–> ganglion–> effector organ in periphery
what is a ganglion?
a group of cells bodies
what is the preganglionic neuron?
before the synapse in the ganglion
what is the postganglionic neuron?
the soma is in the ganglion and the axon goes into the periphery
cholinergic autonomic efferents
all preganglionic neurons synapse on postganglionic receptors that are ACh/nicotinic and result in EPSP
sympathetic efferents to the heart and blood vessels and apocrine sweat glands have adrenergic receptors
sympathetic efferents to eccrine sweat glands have muscarinic receptors
parasympathetic efferents to glands, smooth muscles, heart, and airways have muscarinic receptors and can lead to EPSP or IPSP
apocrine sweat glands
nervous sweating
eccrine sweat glands
temp regulation
what are the neurotransmitters of the ANS?
epinephrine and norepinephrine
what are the adrenergic receptors subtypes?
alpha 1 and 2 and beta 1 and 2
what targets have adrenergic receptors?
sympathetic postganglionic neurons innervating heart, blood vessels
sympathetic postganglionic neurons from the adrenal medulla
where are alpha adrenergic receptors?
arterioles in peripheral smooth muscles and small amounts in the heart and bronchiole muscles
sympathetic efferents
thoracolumbar outflow
innervate thoracic viscera and periphery
innervate abdominal and pelvic organs
innervate adrenal medulla
sympathetic efferents in the thoracic viscera and periphery
synapse in paravertebral ganglia (sympathetic trunk)
travel up and down the sympathetic trunk
sympathetic efferents in the abdominal organs
synapse near the target organs-pass the trunk w/o synapsing
splanchnic nerve
stomach, liver, pancreas, intestines
sympathetic efferents in the adrenal medulla
specialized sympathetic ganglion
secrete NE/E in the bloodstream
sympathetic efferents traveling the paravertebral ganglia
vasculature of limbs, face and upper/lower extremities
sympathetic control of optimal blood supply in organs
optimize blood supply in organs
-stimulate smooth muscle in artery walls–> vasoconstriction (sit to stand, threat/fear)
regulate blood supply in skeletal muscle
- prevents blood pooling by causing vasoconstriction
orthostatic hypotension, syncope
running away
vasoconstrict stomach and GI system
vasodilate muscles
supine to standing
pooling of blood in legs prevented by vasoconstriction in legs to keep you from fainting when standing up
sympathetic control of temp
effects on metabolism
effects on skin
sympathetic control of temp: what is the effect on metabolism?
adrenal medulla releases epinephrine into the bloodstream and this increases the metabolic rate
sympathetic control of temp: what is the effect on skin?
diameter of blood vessels, secretion of sweat, and piloerection
cold: NE binds to alpha adrenergic receptors in skin arterioles
hot: activation of eccrine sweat glands
sympathetic control of blood flow and temp in the head
pupillary dilation
assist in upper eyelid elevation
secretion of thick saliva-dry mouth
sympathetic control of the heart
beta 1 adrenergic
increased HR and contractility
sympathetic control of the lungs
beta 2 adrenergic
dilation of airways
sympathetic control of the GI tract
decrease blood flow
slow/stop peristalsis
reduce glandular secretions
contract sphincters (GI and bowel and bladder)
parasympathetic efferents
cranio-sacral outflow
CN 3, 7, 9, 10 (also go to solitary nucleus)
lateral horn of S2-4
ganglia near or in target organs
main purpose: energy conservation and storage
no innervation to sweat glands, extremity arterioles/veins or hair cells
parasympathetic efferents: CN 3
pupillary constriction
increase convexity of lens-focus on near object and accomodation reflex)
parasympathetic efferents: CN 7 and 9
thin saliva to aid digestion
parasympathetic efferents: CN 7
lacrimal glands-tears
parasympathetic efferents: CN 10
innervates heart, lungs, GI, liver, and kidney
decrease HR
bronchoconstriction
increase peristalsis
increase glycogen synthesis and glandular secretion in the liver
mostly heart function
75% of CN innervation
sacral parasympathetic efferents
S2-4
axons travel in pelvic nerves
emptying of the bowel and bladder
erection of genitalia
bowel and bladder control: filling
sympathetic
involuntary
relax detrusor muscle, contract sphincter
afferent doesn’t have a lot of signal when full, sympathetic efferent (hypogastric nerve) orders the detrusor to be inhibited and internal sphincter to be activated
T10-L2
bowel and bladder control: voiding
parasympathetic
relax sphincter, contract detrusor muscle
afferent signal says the bladder is full
activate pelvic nerve–> activate detrusor, inhibit sphincter
what does reflexive voiding involve?
micturition reflex
not yet potty trained
afferent signal from bladder wall, when full it activates the micturition center of S2-4
pelvic nerve is efferent-contract detrusor
what does voluntary voiding involve?
potty trained
needs pontine and cortical input- brain; pontine micturition center communicates w/sacral micturition center to tell it what to do
pudendal nerve-voluntary motor control relaxes voluntary muscles of sphincter
