Anatomy Chapter 13- Peripheral Nervous System

-no impulses received

-no impulses interpreted

-no motor responses sent out

what would happen to the CNS without the PNS?

afferent fibers

sends sensory info from body → CNS

sensory receptors

respond to stimulus/change

efferent fibers

sends motor response from CNS → effector organ

allow CNS to interpret info

allow CNS to send a response

functions of afferent division?

activate muscles/ glands → carry out response

function of efferent division?

somatic division

skeletal muscle tissue is the effector

autonomic division

cardiac/ smooth muscle (visceral organs) or glands are effectors

mechanoreceptors

thermoreceptors

photoreceptors

chemoreceptors

nociceptors

5 sensory receptor classifications by stimulus type?

non-encapsulated

encapsulated

2 sensory receptor classifications by receptor structure?

exteroceptor

interoceptor

proprioceptor

3 sensory receptor classifications by location?

mechanoreceptor

responds to mechanical force

usually have to change shape of receptor to get the response

thermoreceptor

respond to temperature changes

some only respond to cold or hot, some respond to both

photoreceptor

respond to light

changing intensities allow for color vision

chemoreceptors

respond to chemicals IN SOLUTION only

allows for sense of smell/ taste

can respond to solute concentration of blood/ other bodily fluids

nociceptors

respond to damaging stimuli

provide pain sensation when activated

exteroceptor

found at or near body surface

stimuli from outside of body

interoceptor

found deep in body

stimuli from inside body

proprioceptors

found in skeletal muscle tissue, joints, tendons, ligaments

respond to changes in body position/ movement

ex. stretch of a particular muscle, position of a particular joint

skeletal muscle

tendons

joints

ligaments

4 locations of proprioceptors?

non-encapsulated nerve ending

dendrites have no capsule/ covering

directly exposed to their stimulus= can respond to small changes

found everywhere in body, esp. epithelial & connective tissues

mostly nociceptors/ thermoceptors

nociceptors

thermoreceptors

2 (stimulus based) receptors that almost always have free nerve endings

itch sensation

histamine release activates free nerve endings

chemoreceptor

receptor responsible for itch sensation ?

merkel cells (integument)

cells involved with light pressure stimulus?

mechanoreceptors

receptors around hair follicles are?

encapsulated nerve endings

dendritic ends are enclosed in a capsule

not directly exposed to stimulus= less sensitive

6 types: Lamellar corpuscles, tactile corpuscles, bulbous corpuscles, muscle spindles, tendon organs, joint kinesthetic receptors

mechanoreceptors

what type or receptor almost always has a capsule?

tactile corpuscles

lamellar corpuscles

bulbous corpuscles

muscle spindles

tendon organs

joint kinesthetic receptors

6 types of capsules?

tactile corpuscles

found in dermal papillae of HAIRLESS skin

important for light touch sensation

tactile corpuscles

capsule likely to be found on the underside of your forearm?

lamellar corpuscles

located deep in dermis

stimulated by ONSET of DEEP pressure

bulbous corpuscles

located in dermis, subcutaneous tissue, joint capsules

respond to CONTINUOUS + DEEP pressure

muscle spindles

proprioceptors found in tissue surrounding skeletal muscles

detect muscle stretch, initiate reflexes to resist excessive stressing

prevents muscle tears by initiating a reflexive response

tendon organs

proprioceptors of tendons

initiates reflex that relaxes skeletal muscles to prevent damage to tendon

joint kinesthetic receptor

proprioceptor of joints

provides info ab joint position and motion

ex. weight-bearing loads, whether or not the joint is in use

sensation

awareness of a change in internal/ external environment

perception

how we interpret stimuli, how it makes us feel

somatosensory system

specifically serves body wall and limbs

receives info from extero/interoceptors + proprioceptors

sends impulses to prefrontal cortex for perception

receptor

circuit

perceptual

3 levels of integration allowing perception to occur?

-stimulus matches receptor specificity

-stimulus applied in receptive field

-stimulus is converted to graded potential

-graded potential reaches threshold → action potential

4 requirements for processing at the receptor level

delivering impulses to appropriate region of cerebral cortex (primary somatosensory, prefrontal)

processing at the circuit level includes?

sensory input is interpreted at cerebral cortex

processing at perceptual level includes?

target neurons in cerebral cortex

does identifying & appreciating sensation depend on the message or target neurons in cerebral cortex?

pain triggers

excessive temperature

excessive pressure

chemicals released by damaged cells of injured tissue

histamine

potassium ions

excess ATP

acids

bradykinin (released w tissue damage)

myelinated

fibers carrying sharp pain impulses are?

nonmyelinated

fibers carrying burning pain impulses are?

endorphins (ex. adrenaline)

enkephalins

pain suppressors ?

visceral pain

stimulation of receptors in thorax & abdominal cavity

stimulated by extreme stretch of stomach/ bladder tissue, ischemia, muscle spasms/ cramps, irritating chemicals (like those in spicy food)

ischemia

abnormally low blood flow

organs aren’t getting nutrients they need & can’t dispose of their waste

ex. fingertips hurt in extreme cold

referred pain

pain stimuli arising from one part of the body are perceived as coming from another

visceral pain afferents travel along similar route as somatic pain fibers, brain can get confused by signal and cannot determine exact source

heart attack

patients experiencing __________ often have referred pain in their left arm

nerve

cordlike organ that is part of PNS consisting of bundles of peripheral axons enclosed in connective tissue

sensory

motor

classification of nerve based on type of info?

afferent

efferent

mixed

classification of nerve based on direction in which info is carried ?

sensory

afferent nerves carry _____ info

motor

efferent nerves carry _____ info

towards

afferent nerves carry _____ CNS

away from

efferent nerves carry _____ CNS

mixed nerves

carry info to and from CNS

carry sensory and motor impulses

endoneurium

one single axon is wrapped within the?

perineurium

groups of axons are wrapped within the?

fascicles

bundles of axons are called?

epineurium

fascicles are bundled together by?

PNS

neurons of the ____ have some regenerative capacity

axon

neuron damage can be repaired if it involves the ____ of the neuron ONLY

cell body must be undamaged

distance between severed ends must be short

2 criteria for regeneration to occur?

-axon is damaged

-proximal portion seals itself off

-distal portion disintegrates

step 1 of axon regeneration (3 components)

protects cell body

why would the proximal portion of axon seal itself off after injury?

protects surrounding healthy neurons

why would the distal portion of axon disintegrate after injury?

macrophages invade, destroy dead/ dying portions of neuron

step 2 of axon regeneration

debris would get in the way of regeneration

why must macrophages invade before step 3?

schwann cells release growth hormone to stimulate axon filament growth

schwann cells form a tube

step 3 of axon regeneration (2 components)

macrophage

cell involved in step 2 of axon regeneration?

schwann cells

cell involved in step 3 of axon regeneration?

ensures axon filaments grow in the right direction

why do schwann cells form a tube in step 3 of axon regeneration?

axon filaments grow until they form a complete axon

schwann cells form new myelin sheath

step 4 of axon regeneration (2 components)

regenerated axon diameter is always smaller (action potentials are sent slower)

what is the difference between an undamaged and regenerated axon?

12

# of cranial nerves?

31

# of spinal nerves (pairs) ?

only one of the two athletes felt very good victorious and healthy

cranial nerve mnemonic

olfactory

cranial nerve I

optic

cranial nerve II

oculomotor

cranial nerve III

trochlear

cranial nerve IV

trigeminal

cranial nerve V

abducens

cranial nerve VI

facial

cranial nerve VII

vestibulocochlear

cranial nerve VIII

glossopharyngeal

cranial nerve IX

vagus

cranial nerve X

spinal accessory

cranial nerve XI

hypoglossal

cranial nerve XII

some say marry money but my brother says big brains matter more

sensory/motor/both mnemonic?

olfactory nerve function

sense of smell

optic nerve function

sense of vision

oculomotor nerve function

supplies 4/6 extrinsic eye muscles to move the eyeball

trochlear nerve function

innervates the superior oblique muscle to depress eye and turn it laterally

trigeminal nerve function

supplies sensory fibers to the face and motor fibers to chewing muscles