Autonomic Nervous sytem Flashcards
motor somatic vs autonomic
somatic: lower motor neuron leaves anterior gray horn and innervates skeletal muscle
autonomic: preganglionic neron from lateral gray horn; then postganglionic neuron from autonomic ganglion to effector
- sometimes preganglionic neuron–> adrenal medula–> bloodstream
somatic vs autonomic
- input
- motor control
- neurotrans
somatic:
- somatic and special senses
- voluntary from cerebral cortex (help from basal ganglia, cerebellum, brain stem, and spinal cord)
- all relesase Ach to skeletal muscles
auto:
- interoreceptors (some somatic receptors; some special senses)
- involutary from hypothalamus, limbic, brain stem, spinal cord (a little from cerebellum)
- pregang release Ach; sympathetic postgang release NE
Autonomic reflex arc
stimulus sensory receptor (usually interoreceptor) in viscera dorsal root ganglion integration center pregang axon autonomic ganglion postgang axon effector response
sympathetic division
- “thoracolumbar division”
- preganglionic neurons originate from the thoracic and lumbar levels of spinal cord (T1-L2)
Sympathetic ganglia
- sympathetic trunk (vertebral chain ganglia) = innervate above the diaphragm (right next to spinal cord)
- prevertebral (collateral) ganglia = celiac, superior, mesenteric, inferior mesenteric, aorticorenal, and renal –> below diaphragm
sympathetic pregang vs postgang axons
pregang = many axon collaterals –> synapses with 20+ postgang neurons
postgang = terminate in several visceral effectors –> widespread effect
sympathetic trunk ganglia
3 cervical 11-12 thoracic 4-5 lumbar 4-5 sacral 1 coccygeal
superior cervical ganglion –> head and heart
thoracic sympathetic trunk –> heart, lungs, bronchi
spinal cord to sympathetic trunk ganglia
preganglionic axons –> anterior root of spinal nerve –> white ramus –> sympathetic trunk ganglion
-white rami communnicantes = structures with sympathetic pregang axons that connect the anterior ramus of spinal nerve with ganglia of sympathetic trunk
Gray ramus and gray rami communicantes
gray ramus = axons of postgang neurons leave the sympathetic trunk by entering short pathway called gray ramus and merge with anterior ramus of spinal nerve
gray rami communicantes = structures containing sympathetic postgang axons that connect the ganglia of sympathetic trunk to spinal nerves
options for pregnag neurons in sympathetic division
- synapse with postgang neurons in first ganglion it reaches
- travel up or down sympathetic chain
- continue w/o synapsing thru sympathetic trunk ganglion to prevertebral ganglion
- pass thru sympathetic trunk and prevertebral ganglion to the adrenal medulla
cephalic periarterial nerves
- preganglionic neurons that enter sympathetic trunk, go up to superior cervical ganglion, synapse with postganglion neuron –> postgang neurons leave sympathetic trunk by forming cephalic periarterial nerves –> visceral effectors of skin of face and head
- not a spinal nerve
sympathetic nerves
some axons of postgang neurons leave trunk by forming sympathetic nerves
- innervate heart and lungs
- not a spinal nerve
Splanchnic Nerves
sympathetic, pregang axons pass thru sympathetic trunk to either prevertebral ganglion or adredal medula
% of adrenal medulla
80% epinephrine
20% NE
Prevertebral splanchnic nerves
T5-T9 orT10 = Greater splanchnic nerve
T10-T11 = Lesser splanchnic nerve
L1-L4 = Lumbar splanchnic nerve
Parasympathetic division
“craniosacral division”
-pregang neurons originate from cranial nerves 3,7,9, and 10 and sacral spinal nerves S2-S4
Parasymp ganglia
terminal ganglia
Parasymp pregang vs postgang
pregang synapses with 4-5 postgangs neurons
postgang neurons supply a single visceral effector
not wide spread
dif in size of sympathetic vs parasymp post and pre gangs
symp
- pre = short
- post = long
para
- pre = long
- post = short
Ganglia associated with vagus nerve
- cilary ganglia
- pterygopalatine ganglia
- submandibular ganglia
- otic ganglia
vagus nerve carries 80% of craniosacral flow
sacral parasympathetic flow
S2-S4
-pelvic splanchnic nerves
dual innervation
- most effectors recieve innervation from sympathetic and parasymp divisions
- exceptions: adrenal medulla, sweat glands, smooth muscle around blood vessels, arretor pili, kidney –> only sympathetic
Autonomic plexuses
-network of symp and parasymp axons
-cardiac plexus = heart
-pulmonary plexus = bronchial treaa
-celiac plexus (biggest) = stomach, spleen, pancreas, liver, gallbladder, adrenal medullae
-superior mesenteric plexus = small intestine and proximal colon
-inferior mesenteric plexus = distal colon and rectum
hypogastric plexus = urinary bladder and genital organs
-renal plexus = kidneys and ureters
varicosities of postgang neurons
- swollen distal ends of neuron
- synthesis, storage, and release of neurotrans
- neurotrans release over surface of effector–> diffuses thru interstitial fluid surrounding target cells to bind to receptors
- can affect large area of target –> no specific binding region
- neuroeffector junctions
cholinergic neurons
- release Ach
- include all sump and parasymp pregangs neurons; sump postgangs that innervate sweat glands; all parasymp postgang neurons
cholinergic receptors
- nicotinic (at ganglion)
- Ach binding opens channel for Na+ and K+
- Na+ influx > K+ efflux (electrochem gradient)
- depolarizes postsynaptic membrane - muscarinic (at effector)
- G-prot-coupled receptors (2nd messengers) (activates Adenylate cyclase which activates cAMP which opens channels)
- neurotrans effect depend on receptor type
- can be excitatory or inhibitory
Adrenergic neurons
release NE (also called noradrenalin) -most sympathetic postgang neurons
Adrenergic receptors
Alpha and Beta
-they also bind epinephrine from adrenal medulla
pregangs in general
always myelinated and cholinergic
Autonomic tone
- balance of symp and parasymp activity
- regulated by hypothalamus
sympathetic response
- stress increases sympathetic sysmtem which increases fight-or-flight response
- more ATP production
- dilation of pupils
- dilation of airways
- constriction of blood vessels that supply kidneys and GI tract
- more blood to skeletal muscles, cardiac muscles, liver, and adipose tissue
- more glycogenolysis = more blood glucose
- more lipolysis
Parasympathetic response
- rest and digest
- conserve and restore body energy
- more digestion and urinary func
- less body funcs that support physical activity
- opposite of all sympathetic stuff
integration and control of autonomic functions
- direct innervation = brain stem and spinal cord
- hypothalamus = major control and integration center (recieves input from limbic system) –> emotions can trigger it
dif parts of brain affect on ANS
cerebrum = conscious activity in cerebrum affect hypothalamic control of ANS
Hypothalamus = integration and control center of ANS –> involved in emotions
brain stem = contains major ANS reflex centers
spinal cord = contains ANS reflex centers for defecaton and urinaton
