PNS Anatomy Flashcards
PNS
-everything we sense consciously + unconsciously
-sensory division (afferent) + motor division (efferent)
sensory division (afferent)
somatic sensory and visceral sensory
motor division (efferent)
autonomic and somatic motor systems
autonomic motor system
parasympathetic (calming) and sympathetic (arousing)
somatic sensory
-afferent and how you experience world
-fingertips, pressure on soles of feet
-come out as portions of cranial nerves or spinal nerves and send out very myelinated axons out to effector organs
-do not go through the sympathetic chain
visceral sensory
-gut, liver, kidney
-not conscious of it all the time
-when things hit duandom, certain things are triggered with sensory input of small intestine
somatic motor system
-think and move hand
-send impulse and innervate muscles
autonomic motor system
-regulation of how we go through life
-includes sympathetic and parasympathetic divisions
parasympathetic system
-“rest and digest”
-brings everything down
-Acetylcholine is the primary neurotransmitter
Ex. meds utilize this like eye drops for glaucoma to constrict pupils
-long preganglionic fibers and short postganglionic fibers
-ganglia in or near effector organs
-pregangionlic fibers emerge from cranial or sacral regions of CNS
-preganglionic fiber exits spinal cord and travels long distance out to effector organ with ganglia where synapse occurs
sympathetic system
-“fight or flight”
-send resources to the right places at the right times
-involuntary but some pathways you can exert conscious control
-generally speaking unconscious and uncontrolled
-controls visceral organs, mostly involuntary
-2 neuron network but where synapse occurs matters
-short preganglionic fibers and long postganglionic fibers
-preganglionic fibers emerge from thoracic and lumbar regions
-also innervates adrenal medulla —> Epinephrine (adrenaline) is primary neurotransmitter
-upregulates body functions and ganglion is sympathetic chain that runs along spinal cord
ganglia in the parasympathetic system
-basilary ganglia- controls pupil
-pterygopalatine- provides sensation and regulates secretomotor functions for the mucous membranes of the nasal cavity, oropharynx, nasopharynx, and upper oral cavity
-submandibular- controls saliva secretion, which helps lubricate the oral cavity, aid in digestion, and make food easier to swallow
-otic- transmits parasympathetic and sympathetic fibers to the parotid gland
what nerves give parasympathetic innervations?
from brainstem:
-oculomotor
-facial
-glossopharyngeal
-vagus
from gut:
-pelvic
what does the vagus nerve do for parasympathetic contributions?
-helps with calming and regulatory pulses since we are constantly firing up the heart/slowing down, digestion, and adrenal gland
-single nerve has contributions on parasympathetic side to all of the viscera
-through evolution, the vagus nerve sits high and goes down low —> if you injure your spinal cord, you can still live since the vagus nerve is alive
sympathetic chain
-the sympathetic contributions start at T1 and goes down to L5
-innervation goes directly from chain to heart, stomach, liver, and other organs
how are nerves named?
-C1 is where the sympathetic trunk begins —> comes out between the skull and first vertebra
-7th cervical nerve is the spinous process
-C8 has a nerve above and below
-@ C7 you have switch from being named for the vertebra below to the vertebra above for thoracic and lumbar nerves
parasympathetic nerves vs sympathetic nerves
parasympathetic (rest and digest):
-constricts pupils
-stimulates saliva
-slow heartbeat
-constrict airways
-stimulate activity of stomach
-inhibit release of glucose; stimulate gallbladder
-stimulate activity of intestines
-contract bladder
-promote erection of genitals
sympathetic (fight or flight):
-dilate pupils
-inhibit salivation
-increase heartbeat
-relax airways
-inhibit activity of stomach
-stimulate release of glucose; inhibit gallbladder
-inhibit activity of intestines
-secrete epinephrine and norepinephrine
-relax bladder
-promote ejaculation and vaginal contraction
dorsal and ventral roots
-parasympathetic and sympathetic are only efferent
-motor is always associated with ventral root and dorsal root is always sensory
sympathetic chain
-ventral root meets dorsal root (motor and sensory) —> form the spinal nerve
-dorsal ramus (branch) and ventral branch that comes out
-sympathetic chain runs along spinal cord communicating with ganglion
-1st short pre-ganglionic fiber comes from lateral horn and travels through the rootlets, through the ventral root into the spinal cord proper —> white ramus into ganglion