PNS I

how many cranial nerves

12 pairs

how many spinal nerves

31 pairs

sensory receptors are activated by

stimuli

mechanoreceptors

feel movement of touch, sense stretch pressure vibration

proprioreceptors

balance

thermoreceptors

sense temp

photoreceptors

respond to light, retina of eye

chemoreceptors

chemical sensing; taste and smell

nociceptors

sense pain

do you think different people can have different thresholds for pain

no we all have same threshold tolerance is different

visceral pain

stomach hurts

referred pain

pain in body that isnt in origin; left arm pain during heart attack

exteroceptors

outside of body

interceptors

receive info from within body; also called visceroceptors; pain hunger thirst

proprioceptors

balance; where we are to maintain balance; in skeletal muscles tendons, joints, ligaments and CT

nerve

bundle of neurons/axons

mixed nerves

contain both sensory and motor fibers; impulses travel both to and from CNS

sensor (afferent) nerves

impulses ONLY toward CNS

motor (efferent) nerves

impulses ONLY away from CNS

most nerves

are mixed; rarely pure motor or sensory

somatic afferent

sensory from muscle to brain

somatic efferent

motor from brain to muscle

visceral afferent

sensory from organs to brain

visceral efferent

motor from brain to organs

ganglia

bundle of cell bodies in PNS

ganglia associated with

afferent to brain (dorsal sensory)

tingling numb arm=

crush injury to axon (mild heals)

PNS has great ability

to repair damaged nerves

Nerve repair is

distally

Axon damage

damaged repairs distally toward axon terminal, macrophages clean up mess, schwann cells make myelin, axons grow through regeneration tube, axon regenerates

31 pairs of

spinal nerves

all spinal nerves are

mixed

pairs of cervical nerves

8 C1-C8

pairs of thoracic nerves

12 T1-T12

pairs of lumbar nerves

5 pairs L1-L5

pairs of sacral nerves

5 pairs S1-S5

pair of coccygeal nerves

1 pair C0

dorsal ramus and ventral ramus

branch off spinal nerve

dorsal ramus

smaller branch, goes to back of bod

ventral ramus

larger ramus, more involved, goes to front, supplies more organs and muscles

nerve plexus

bundle of all rami, various levels of rami join together