Anatomy Exam 3: PNS (part 1)

PNS

has pathways out of the brain + spinal cord

somatic motor pathways

• innervate skeletal muscles

  • involuntary actions

• single neuron in pathway

  • cell body of neuron in spinal cord (or brain)

  • single long axon to muscle

visceral/autonomic system

• parasympathetic division

• sympathetic division

• enteric division

• sends signals to cardiac muscle, smooth muscle, glands, and organs

parasympathetic division

• apart of visceral autonomic system

• rest and digest

sympathetic divison

• apart of visceral/autonomic system

• action (fight or flight)

• adrenal medulla

enteric division

• apart of visceral/autonomic system

• digestive reflexes

peripheral parasympathetic and sympathetic pathways

• pathways in autonomic system

• two neurons which synapse in autonomic ganglion

  • preganglionic

  • post ganglionic neuron

preganglionic

• one out of two neurons which synapse in autonomic ganglion

• myelinated

• releases AcH

postganglionic neuron

• one out of two neurons which synapse in autonomic ganglion

• not myelinated

• releases AcH or nore/epi

parasympathetic pathways

• leave CNS from BRAINSTEM or along SACRAL SPINAL NERVES

• synapse in autonomic ganglion NEAR OR IN EFFECTOR

• release primarily ACH from postganglionic neuron to target

• travel through cranial nerves

  • 90% through vagus nerve (also oculomotor, facial, and glossopharyngeal nerves)

    • many pathways pass through autonomic nerve plexuses

sympathetic pathways

• leave CNS along THORACIC or LUMBAR SPINAL NERVES

• synpase in autonomic ganglion near VERTEBRAL COLUMN

  • chain ganglia

  • collateral ganglia

• release primarily NORE/EPI to targets

  • AcH release to sweat glands

adrenal medulla

• inner part of adrenal gland

  • modified sympathetic ganglion

• postganglionic cells release neurohormones into blood

  • primarily adrenaline/epinephrine

  • smaller amounts of noradrenaline/norepinephrine

• boosts and extends some sympathetic responses

enteric nervous system

• regulates digestive reflexes

• myenteric plexus

• submucosal plexus

myenteric plexus

• apart of enteric nervous system

• regulates smooth muscle of digestive tract

submucosal plexus

• apart of enteric nervous system

• regulates secretion; monitors chemical enviornment

somatic system

• cervical plexus

• brachial plexus

• intercostal nerves

• lumbar plexus

• sacral plexus

cervical/brachial plexus

• apart of somatic system

• has phrenic nerve

  • innervates diaphragm

brachial plexus

• apart of somatic system

• has phrenic nerve, musculocutaneous, axillary, median, radial, ulnar nerves

  • innervates arm

intercostal nerves

• apart of somatic system

• innervate trunk

lumbar plexus

• apart of somatic system

• femoral nerve

  • innervates anterior part of leg

sacral plexus

• apart of somatic system

• sciatic nerve

  • innervates posterior part of leg

sympathetic synapse in chain ganglion

spinal cord ——» ventral root ——» white ramus ——» chain ganglion

sympathetic: synapse in collateral ganglion

spinal cord ——» ventral root ——» white ramus ——» sympathetic trunk ——» chain ganglion ——» splanchnic nerve ——» collateral ganglion

eye (parasymp response)

constriction of pupil

eye (symp response)

dilation of pupil

salivary glands (parasymp response)

secretion of saliva

salivary glands (symp response)

inhibition of saliva

heart (parasymp response)

decrease HR

heart (symp response)

increased HR

airways (parasym response)

constriction of airways

airways (symp response)

dilation of airways

digestive system (parasymp response)

increased digestive activity

digestive system (symp response)

decreased digestive activity

urinary bladder (parasymp response)

urination

urinary bladder (symp response)

inhibition of urination

parasymp response only has this

• lacrimal glands

  • secretion of tears

symp response only has this

• vasoconstriction/vasodilation

• sweat glands activated

• arrector pili muscle (goose bumps)