M10 - Autonomic Nervous System Flashcards
Somatic nervous system
voluntary, skeletal muscles, 1 LMN, no synapse, high + rapid myelination, excites cells, origin at ventral horn
Autonomic nervous system
Involuntary, cardiac and smooth muscles and glandular tissue, 2 LMN, synapse, lightly myelinated preganglionic, unmyelinated postganglionic, slow speed, can excite and inhibit, original at lateral horn
Sympathetic ANS
Fight or flight, origin at thoracic and first 2 lumbar lvls of spinal cord, short preganglionic, long postganglionic, ganglia close to spinal cord in sympathetic trunk or prevertebral ganglia, widespread response, between pre and postganglionic neurons = acetylcholine, between post and effector = norepinephrine
Parasympathetic ANS
Rest and digest, origin at brainstem and cranial nerves, long preganglionic, short postganglionic, terminal ganglia near target organ, intramural ganglia in wall of target organ, local response, between pre and postganglionic neurons = acetylcholine, between post and effector = acetylcholine
Autonomic plexuses
Collections of sympathetic postganglionic axons, parasympathetic preganglionic axons, and visceral sensory axons
Sympathetic and parasympathetic axons travel together to reach destination
Cranial nerves
Oculomotor (CN III), facial (CN VII), glossopharyngeal (CN IX), vagus (CN X) - innervates majority of thoracic and abdominal organs
Pelvic splanchnic nerves
Emerge from sacral region, contribute to hypogastric plexus
Vagus nerve
Cardiac, pulmonary, esophageal, celiac, superior mesenteric, inferior mesenteric plexus
Cardiac plexus
Innervates heart, lowers heart rate
Pulmonary plexus
Innervates lungs & bronchi, reduced respiratory rate and constriction of bronchi
Esophageal plexus
Innervates smooth muscle in lower esophagus
Celiac plexus
Innervates foregut organs - digestive tract from lower portion of esophagus thru first 2 parts of duodenum + accessory digestive organs
Superior mesenteric plexus
Innervates midgut organs - 3rd part of duodenum thru first 2/3 of transverse colon
Hypogastric plexus
Innervates abdominal and pelvic organs, leads to inferior mesenteric plexus and pelvic organs - bladder and reproductive organs
Inferior mesenteric plexus
Innervates hindgut organs - digestive organs from last 1/3 of transverse colon to end of digestive tract
Sympathetic division
Thoracolumbar division, fibers leave spinal cord thru thoracic and first 2 lumbar lvls, enter sympathetic trunk
Sympathetic trunk
located lateral to vertebral column bilaterally, start in lateral horn thru ventral root to white rami communicantes, several options after that
White rami communicantes
Preganglionic sympathetic axons of T1-L2 spinal nerves, myelinated, part of every single sympathetic pathway
Gray rami communicantes
Postganglionic sympathetic axons from sympathetic trunk to spinal nerve, unmyelinated, only present in spinal nerve pathway
Prevertebral ganglia
Collections of cell bodies immediately anterior to vertebral column on anterolateral surface of aorta, cluster around arteries
Celiac ganglia - foregut
Superior mesenteric ganglia - midgut
Inferior mesenteric ganglia - hindgut
Spinal nerve pathway
Starts in lateral horn, thru ventral root into spinal nerve, thru white rami into sympathetic chain, synapse in sympathetic chain ganglia, postganglionic axon travels thru gray rami back to spinal nerve, origin of T1-L2, some fibers will travel to superior, middle, and inferior cervical ganglia, some will travel inferiorly to sacral portions, target is integumentary, innervates arrector pili muscles, sweat glands, and blood vessels
Postganglionic sympathetic pathway
Cell body in lateral horn, thru ventral root into spinal nerve, thru white rami into sympathetic chain, ascend within sympathetic chain to superior, central, and inferior cervical ganglia, synapse in 1 of 3 ganglia, exit chain, origin of T1-T5
Superior cervical ganglia
Go to head
Middle and inferior cervical ganglia
Go to thoracic organs, travel thru cardiac (incr heart rate) & pulmonary (incr rate of respiration, dilating bronchi) & esophageal plexuses (smooth muscle of esophagus)
Splanchnic nerve pathway
Largest and most complex, 1 vertebral ganglia that split into R and L, not bilateral, origins T5-L2, cell body in lateral horn, thru ventral root into spinal nerve, thru white rami to sympathetic chain, exit chain towards midline anterior to aorta
Greater splanchnic nerve
T5-T9, go to celiac ganglion, foregut
Lesser splanchnic nerve
T10-T11, superior mesenteric ganglion, midgut
Least splanchnic nerve
T12, also to superior & inferior mesenteric ganglion, hindgut
Lumbar splanchnic nerve
L1-L2, inferior mesenteric ganglion, hindgut
Sacral extension of splanchnic nerve pathway
Synapse on postganglionic neurons within sympathetic chain, postganglionic neurons send fibers out to sacral splanchnic nerves, travel thru hypogastric plexus to pelvic organs
Adrenal medulla pathway
Cell body in lateral horn, thru ventral root to spinal nerve, thru white rami to sympathetic chain, leave chain to adrenal medulla, origin T8-T12, no postganglionic neuron, secrete norepinephrine and epinephrine, help w coping for stress/danger
Referred pain
Occurs when impulses from certain viscera are perceived as originating not from organ but in dermatome of skin
