BIO 201 (CNS/ PNS) [exam 3]

the PNS is composed of…..

nerves, ganglia, sensory receptors, and efferent nerve endings

nerve

cordlike organ

T/F: a nerve has only 1 fiber bond together by CT

F, numerous

spinal nerve axons are grouped within _____

CT sheaths

endoneurium w/ a single axon

fiber

perineurium w/ bundle of fibers

fascicle

epineurium w/ bundle of fascicles

nerve

T/F: within nervous coverings there are numerous blood vessels

T

how are peripheral nerves classified

direction in which they transmit impulses

mixed nerves

contain both sensory and motor fibers

sensory (afferent)

carry impulses toward CNS

motor (efferent)

carry impulses away from CNS

ganglia

collection of neuron cell bodies associated with nerves in the PNS

ganglia associated with afferent are cell bodies of ____

sensory neurons

ganglia associated with efferent are cell bodies of ____

autonomic motor neurons

T/F: PNS axons that are damaged cannot be regenerated

F, only if cell body remains intact

____ participate in regenrating PNS axons

schwann cells

sensory receptors

specialized cells structures that collect information form environment

sensory receptors stimulate ____ to send impulses along sensory fibers of the brain

neurons

what are the different way in which receptors can be classified

modality, stimulus, and distribution

thermoreceptors

respond to heat and cold

photoreceptors

respond to light

nocireceptors

respond to injury/ potentially damaging situations

chemoreceptors

respond to chemicals (odors, tastes, body fluid composition)

mechanorecpetors

respond to physical deformation caused by vibrations, touch, pressure, stretch, or tension

exterorecpetors

senses stimuli external to body

interoceptors

detect stimuli in internal organs

proprioceptors

sense position and movements of the body or its parts

general (somatic) senses

employ receptors widely distributed in the skin, muscles, tendons, joint capsules, and vicera

special senses

limited to the head and employ complex sense organs

how are sensory receptors described

free nerve endings, cilia, encapsulated nerve endings and the dendrites of a- order sensory neuron

encapsulated nerve endings

nerve fibers wrapped in glial cells or CT

encapsulated nerve endings are mostly _____

mechanoreceptors

tactile

sensations are touch, pressure, and vibration plus itch and tickle

crude touch

ability to perceive that something has simply touched skin

fine touch

provide specific info about touch sensation such as location, shape, size, and texture

pressure

tactile receptors deep in tissues and are longer lasting and have less variation in intensity

vibration

rapidly repetitive sensory signals from tactile receptors

receptors for vibrations sensations are _____

corpuscles and lamellated corpuscles

bare dendrites

lack structural specializations (simplest receptors)

____ are common in epithelial tissues

free nerve endings

free nerve endings

respond to pain, temp, tickle, and some touch

____ is the only sensation that we cannot elicit on ourselves

tickle

tonic receptors

light touch and also textures, edges, and shapes

what are the 2 slowly adapting touch receptors

Merkel’s discs and ruffini corpuscles

how are merkel’s disc shaped

saucer- shaped, flattened free nerve endings

where are merkel’s discs found

fingertips, hands, lips, and external genitalia

merkel’s disc a.k.a

tactile receptor

hair root plexuses (sensory receptors)

rapidly adapting touch receptors (not constantly stimulated by clothing)

T/F: hair root plexuses are slow to adapt

F, rapid so we aren’t always thinking about what we are wearing

function of hair root plexuses

detect movements on skin surface that disturb hairs

meissner’s corpuscles (sensory receptors)

2-3 nerve fibers meandering upward through masses of flattened schwann cells

what are the 2 rapidly adapting receptors

Meissner’s corpuscles and hair root plexuses

where are meissner’s corpuscles found

dermal papillae ( fingertips, hands, eyelids, tip of tongue, lips, nipples, etc)

_____ generate impluses mainly at onset of touch

Meissner’s corpuscles

pacinian (lamellated) corpuscles (sensory receptors)

multilayered CT capsules that enclose dendrite (look like sliced onion in cross section)

phasic receptors

fast adapting receptors

where are pacinian (lamellated) corpuscles found

deeper subcutaneous tissues, tendons & ligaments, periosteum of bone, etc

pacinian (lamellated) corpuscles feel

heavy pressure, vibrations, and stretching

ruffini’s corpuscles (sensory receptors)

tonic receptors for heavy touch, pressure, skin stretching, and joint movements

where do we find ruffini’s corpuscles

deep in dermis and in ligaments & tendons, in hands, and soles

proprioreceptive sensation convey nerve impulses related to

muscle tone, movement of body parts, and body position

pacinian corpuscles (proprioceptors)

speed of joint movement

muscles spindles (propriorecpetors)

proprioceptors in skm that monitor changes in the length of skm and participate in stretch reflexes

golgi tendon organ

stretch receptors protect from over stretching

where are golgi tendon organs found

junction of a tendon and muscle

what temp do we sense cold

10 C - 20 C (50 F- 68 F)

what temp do we sense heat

25 C (77 F)

when do we not sense heat

45 C (113 F)

pain

vital sensation as it provides info about tissue- damaging stimuli

where do we find nociceptors in the brain

meninges

nociceptors in meninges detect ____

headaches

what 2 pain recognized in parietal lobe of cortex

somatic (superficial and deep), visceral 

pain signals from head

travel to brainstem by way of 4 cranial nerve (5, 7, 9, 10)

pain signals from the neck down

travel by way of 3 ascending spinal cord tracts (spinothalamic, spinoreticualar, and gracile fasciculus)

where do pain signals from the head terminate

medualla

where do pain signals from the neck down terminate

thalamus

referred pain

pain in viscera mistakenly thought to come form skin or other superficial sites

phantom pain

sensation of pain in a limb that has been amputated

which cranial nerve wanders into the thorax and abdomen

vagus

CN 1

olfactory I

CN 2

optic II

CN 3

oculomotor III

CN 4

trochlear IV

CN 5

trigeminal V

CN 6

abducens VI

CN 7

facial VII

CN 8

vestibulocochlear VIII

CN 9

glossopharyngeal IX

CN 10

vagus X

CN 11

accessory XI

CN 12

hypoglossal XII

olfactory I

transmit impusles associated with detecting odors 

optic II

transmit impulses associated with vision

oculomotor III

controls muscles that move eye up, down, medially; in addition to iris, lens and raise upper eyelid

accomodation

focus lens

pupil diameter

adjust light entering

trochlear IV

controls superior oblique that rotates eye and slightly depress

trigeminal V

sensation of the face and motor control for chewing 

ophthalmic division/ maxillary division

sensory from surface of eyes, tear glands, scalp, and forehead (upper face sensation)