PNS exam Flashcards
(106 cards)
1
Q
PNS components and associated structures
A
nerve fibers and cell bodies OUTSIDE THE CNS that conduct impulses to/away from the CNS
cranial and spinal nerves
2
Q
nerve
A
cord-like organ made up of parallel bundles of peripheral axons enclosed by successive wrappings of CT
3
Q
ganglion
A
collection of PNS nerve cell bodies
outside the cord in dorsal root ganglion
anterior horn of ventral root
4
Q
nerve fiber consists of
A
axon, neurilemma, and surrounding endoneurial CT
5
Q
endoneurium
A
delicate loose CT that surrounds the axons and neurilemma
6
Q
perineurium
A
single layer of dense CT that encloses a fascicle and provides protection against foreign substances
7
Q
epineurium
A
tough fibrous sheath that encloses all the fascicles
includes fatty tissue, bv, and lymphatics
8
Q
classification of nerves: sensory/afferent
A
carries impulses towards the CNS
9
Q
classification of nerves: motor/efferent
A
carries impulses away from the CNS to effectors
10
Q
classification of nerves: mixed
A
most common
carry motor+sensory info to and from the CNS
11
Q
a damaged neuron can regenerate only if
A
the soma remains intact
12
Q
nerve regeneration
A
- wallerian degen- separated ends of the axon seal themselves off and swell disintegrating the distal part of the axon
- macrophages remove debris to clean out the dead axon leaving the myelin sheath intact and they stimulate schwann cells to divide
- schwann cells form a regeneration tube that the axon filament sprouts grow thru to be guided across the gap to their original contacts
- the axon regenerates and a new myelin sheath forms
13
Q
cranial nerve I
A
olfactory
sensory/afferent for smell
14
Q
cranial nerve II
A
optic
sensory/afferent for vision
15
Q
cranial nerve III
A
oculomotor motor and parasympathetic fibers for eye movement elevation of eyelid pupil constriction+ ciliary muscle
16
Q
cranial nerve IV
A
trochlear
motor to supply superior oblique muscle
smallest nerve but longest pathway
17
Q
cranial nerve V
A
trigeminal mixed motor for mastication sensory for face divided into opthalamic, maxillary, and mandibular
18
Q
cranial nerve VI
A
abducens
motor
serves lateral rectus muscle allowing eye to abduct
19
Q
cranial nerve VII
A
facial
mixed (stylomastoid foramen) mainly for smile/laugh
motor for muscles of face and scalp
sensory for taste buds
*parasympathetic fibers for salivary and lacrimal glands
20
Q
cranial nerve VIII
A
vestibulochochlear
sensory
vestibular nerve for equilbruim
cochlear nerve for hearing
21
Q
cranial nerve IX
A
glossopharyngeal
parasympathetic fibers
mixed (jugular foramen)
motor for muscles of pharynx/salivary glands
sensory for pharynx sensation, tonsils, posterior 1/3 of tongue, bp in carotid arteries
22
Q
cranial nerve X
A
vagus
mixed (jugular foramen)
motor/ paraympathetic (except swallow), supplies heart, lungs, abdominal viscera, involved in heart rate/breathing/digestion
sensory for impulses from thoracic/abdominal viscera, aortic/carotid chemoreceptors and taste buds on tongue and pharynx
only cranial nerve to extend beyond head/neck to thorax/abdomen
23
Q
cranial nerve XI
A
accessory
mixed (jugular foramen)
motor ctrls muscles of pharynx, sternocleidomastoid, trapezius,
sensory for proprioceptors of above muscles
24
Q
cranial nerve XII
A
hypoglossal mixed motor for muscle of tongue sensory for proprioceptors of tongue allows food mixing/manip by tongue and swallowing and speech involving the tongue
25
spinal nerves
initially arise from spinal cord as rootless but converge to form 2 nerve roots
all are mixed nerves
8 cervical, 12 thoracic, 5 lumbar, 5 coccygeal
31 pairs
26
dorsal root
sensory/afferent info
| cell bodies are located outside the cord in dorsal root ganglion
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ventral root
motor/efferent info
| cell bodies lie in anterior horn
28
posterior dorsal ramus
serves deep muscles and skin of dorsal trunk
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anterior ventral ramus
serves muscles/structures of upper/lower limbs and skin of lateral/ventral trunk
30
rami communicates
autonomic visceral sympathetic nerve fibers
31
cranial nerves for eye movement
III oculomotor
IV trochlear
VI abducens
32
cranial nerves that are mostly sensory
I olfactory
II optic
VIII vestibulocochlear
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cranial nerves with parasympathetic fibers that serve visceral muscles and glands
III oculomotor
VII facial
IX glossopharyngeal
X vagus
34
plexus
network of tangled nerves that mostly serve limbs
formed by ventral rami
each end of the plexus contains fibers from several spinal nerves
35
cervical plexus
C1-C4
phrenic nerve C3-C5
most important nerve
sensory/motor fibers to diaphragm
36
brachial plexus
C5-C8 and T1
entire nerve supply to upper extremities, neck, and shoulder muscles
radial, median, ulnar
37
lumbar plexus
L1-L4
abdominal wall, external genitals, part of lower extremities
femoral-largest part of lumbar plexus serves thigh, buttocks, and lower extremities
38
sacral plexus
L4-L5 and S1-S4
sciatic nerve-thickest and longest of all
serves anterior thigh muscles, and medial surface of leg knee-foot
39
spinal nerve in charge of contracting the diaphragm
phrenic nerve C3-C5
40
radial nerve
part of brachial plexus
| goes under olecranon- called the funny bone
41
ulnar nerve
part of brachial plexus
| on the medial side of the arm, innervates the pinky and ring finger
42
median nerve
part of brachial plexus
innervates thumb, index, and middle finger
can cause carpal tunnel
43
somatic nervous system
peripheral nerve fibers for voluntary motor info (excitatory) to the skeletal muscle
reflexive movements
a single neuron arising from ventral horns
ACH is only neurotransmitter
44
autonomic nervous system
ctrls smooth muscle of viscera/internal organs and glands
| sympathetic, parasympathetic, and enteric
45
somatic effectors, pathways, and neurotrans
effector: skeletal muscle
effector pathway: single heavily myelinated neuron
neurotrans: ACH
46
autonomic effectors, pathways, and neurotrans
effector: smooth/cardiac muscles and glands
effector pathway: 2 neurons; pregang 1 light myel neuron, post gang 1 unmyel neuron
neurotrans: pregang- ACH, post gang NRE stim, ACH inhibit
47
ANS sympathetic division origin, length of fibers, neurotransmitters
origin: thoracic and lumbar
length of fibers: pregang-long, postgang- short
neurotrans: pregang-ACH, postgang NRE
48
sympathetic division innervation
```
pupil-dialates
salivary glands-inhibits
heart-accelerates
lungs- dialates bronchi
digestive- inhibits
liver- converts glycogen to glucose
bladder-inhibits contraction/release
secretes adrenaline and Noreadrenaline
```
49
ANS parasympathetic division origin, length of fibers, and neurotrans
origin: cranial nerves and sacral
length of fibers: pregang-short, postgang-long
neurotransmitter: pregang ACH, postgang-ACH
50
parasympathetic division innervation
```
pupil-constricts
salivary glands- stimulates
heart-slows
lungs- bronchi constrict
digestive- stimulates peristalsis and secretion
liver- stimulates bile release
bladder- contracts and release
```
51
main functions of general sensory receptors and special senses
keep us aware and able to respond to stimuli in envt
allow survival
special senses allow for vision, olfaction, taste, hearing, equilibrium
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by stimulus
| mechanoreceptors
```
touch
pressure
vibration
stretch
itch
meissners corpuscles
```
53
by stimulus
| thermoreceptors
free nerve endings
| sensitive to temperature changes
54
by stimulus
| photoreceptors
in retina
| resp to light
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by stimulus
| chemoreceptors
in hypothalamus, vomiting center, heart
smell
taste
changes in blood chemistry
56
by stimulus
| noiceptor
free nerve endings
| sensitive to pain causing stimuli
57
by location
| exteroceptors
```
found near the body surface
respond to stimuli arising outside the body
touch
pressure
pain
temperature
and special sense organs
```
58
by location
| interoceptors
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found in internal viscera/bv
resp to stimuli arising within the body
chemical changes
stretch
temperature changes
```
59
proprioceptors
interoceptor that responds to degree of organ stretch in skeletal muscles, tendons, joints, ligaments, CT coverings
constantly advise the brain of movement
60
the 5 special senses are
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vision
olfaction
taste
hearing
equilibrium
```
61
accessory eye structures: eyebrows
coarse hairs that overlie supraorbital margins to shade the eye and stop perspiration from reaching the eye
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accessory eye structure: eyelids
overlying skin that protects the eye anteriorly and produces lubricating mucus to keep the eye from drying out
63
accessory eye structure: tarsal glands
secrete whitish oily fatty substance
64
accessory eye structure: lacrimal apparatus
lacrimal glands and associated ducts
| secrete tears; a dilute saline solution with mucous, antibodies, and lysozymes
65
accessory eye structure: lens
biconvex transparent avascular structure that allows precise focus of light on to the retina
composed of simple cuboidal epithelium in the anterior cells that differentiate into lens fibers
and lens fibers-cells filled with transparent protein crystalin
66
fibrous tunic of eyeball
slcera-protection and anchoring of extrinsic muscles; covered by conjuntiva
cornea- curved to help focus light on the retina
67
vascular tunic (uvea)
choroid- highly vascularized dark brown membrane bt sclera and retina that helps absorb light and supplies blood to all tunics
ciliary body-thickened ring of tissue surrounding the lens ciliary muscles are smooth muscle bundles to ctrl lens shape
ciliary processes secrete aqueous humor and anchor suspensory ligament that holds the lens in place
iris and pupil- colored part of eye ctrl amt of light
68
sensory tunic (retina)
ora serrata- attaches ciliary body to sensory tunic
2 layer membrane- pigmented layer that absorbs light/prevents scattering/acts like phagocytes; retina- multi layered outgrowth of brain w photo receptors, bipolar cells, ganglion that joins optic disk and leaves as optic nerve
69
anterior chamber
bt cornea and iris
cont aqueous humor- a plasma like fluid that drains via canal of schlemm (scleral venous sinus)
supports nourishes and removes waste
70
posterior chamber
bt iris and lens
cont vitreous humor- clear gel that supports the posterior surface of the lens; and holds the neural retina firmly against the pigmented layer
71
main structure of the eye that regulates the amout of light passing to the visual receptors of the eye
pupil
72
flow of light
cornea--aqueous humor of anterior seg--pupil-lens--vitreous humor of posterior segment--ganglion cells--bipolar cells--photoreceptors
73
rods
```
sensitive to dim light
best suited for night vision/peripheral vision
1 photopigment-rhodopsin
input in gray tones
fuzzy/indistinct images
```
74
cones
high acuity color vision
requires bright light for activation (low sensitivity)
detailed and high res in blue, red, and green
found in macula lutea and concentrated in fovea capitis
75
arrangement of photopigments
rods/cones arranged in a stack of disk like infoldings of plasma membrane that change shape as they absorb light
76
visual pigments
colored proteins that undergo structural changes when they absorb light creating potentials
77
opsin-
visual pigment
glycoprotein bound to retinal
4 types
78
retinal
derivative of vit A
light absorbing part
wavelength depends on which opsin is attached
79
visual transduction of rods
bleaching of pigment- breakdown of retinal opsin combo;
regeneration- retinal binds to opsin
rhodopsin- deep purple pigment in rods that absorbs blue-green
80
visual transduction of cones
visual pigments retinal and opsin
dark- continual release of glutamate--no vision
light-no glutamate--light+vision
81
smell
olfactory epithelium
covers superior part of nasal cavity
bipolar neurons with radiating olfactory CILIA embedded in mucus
82
taste
taste buds found in papillae on tongue
bud made up of supporting cells that insulatethe receptor, basal cells/stem cells, GUSTATORY HAIRS that bind molecules and release serotonin and ATP
83
activation of smell
1. olfactory receptors bind odor causing chemicals
2. use CAMP as 2nd messenger to initiate G protein mechanism
3. CAMP opens NaCa+ channels to trigger an action potential
84
activation of taste
1. chemical must be dissolved in saliva and bound to gustatory hairs
2. binding of food chemical depolarizes taste cell membrane releasing neurotransmitter and initiating action potential and starting digestion
3. thermoreceptors, mechanoreceptors, nociceptors, and texture influence taste
85
5 different tastes
sweet-sugars, saccharin, alcohol, aminos
salt-metal ions like NaCl
sour- acids H+
bitter- alkaloids like caffeine and nicotine
umami- meaty flavor from aminos, glutamate, aspartate
86
papillae that contain taste buds
foliate
fungiform
circumvallate
87
composition of a taste bud
supporting cells-insulate the receptor
basal cells-dynamic stem cells
gustatory hairs- taste cells
88
outer ear composed of
auricle (pinna)- helix/rim and lobule
external acoustic meatus-short curved tube filled w ceruminous glands
typmanic memb- CT memb bt outer/mid ear that vibrates and transfers sound energy to ossicles
89
middle ear
small air filled mucosa lined cavity flanked laterally by tympanic memb and flanked medially by oval and round windows
pharyngotympanic tube- equalizes pressure in middle ear w external air
ossicles- (malleus, incus, stapes) transmit vibratory motion of tympanic membrane to oval window
90
inner ear
cochlea_ spiral conical bony chamber that is divided into
scala vestibuli-upper, connected to oval window, perilymph
scala tympani- lower, terminates at round window serves as pressure valve, perilymph
scala media- middle cochlear duct filled with endolymph, high K+ conc
91
receptor for hearing is
the organ of corti
part of inner ear enclosed by tectorial memb- upper memb touched by hairs; and basal memb- separates scala media from scala tympani, where hair cells are embedded
92
two groups of hair cells in the inner ear
inner cells- single row
| outer cells-three rows
93
sterocilia on the apical side of cells
extend to endolymph of scala media
long microvilli arranged in several rows of graded height (longest called kinocilium)
at basal end both types of cells synapse w sensory neurons from the cochlear branch of CN VIII
94
physiology of sound
1. sound vibrations beat on tympanic membrane
2. tympanic memb pushes against the ossicles which press fluid in the inner ear against oval/round windows setting shearing forces that pull hairs
3 cilia bend towards kinocilium
-opens mech gated K+ channels
-cause graded pot and release of neurotrans
-neurotrans cause cochlea fibers to trans impulses to brain where sound is received
95
vestibule
central egg shaped cavity of bony labyrinth; 2 sacs depended in perilymph,
saccule-extends 2 cochlea- resp to verticle mvmt
utricle-extends to semicircular canals-resp to horiz mvmt
96
static equilbruim
macula of vestibula
monitor pos of head in space and controls posture
resp to speed/direction but not rotation
supporting cells and hair cells
-each hair has stereocilia +kinocilium in the otolithic memb- jelly like mass studded w tiny calcium carbonate stones called otoliths
97
static equilbruim activation
otolithic mvmt in direction of kinocilia-depol vestibular nerve fibers, increase number of AP
otholithic mvmt away from kinocilia- hyperpol/ reduces the rate of impulses
either way the brain is informed of changing pos of head bc hair cells synapse w fibers of vestibular nerve
98
dynamic equilbrium
crista ampularis of semicircular canals
ampula-swollen end of each canal-has eq receptors called crista ampularis
resp to angular mvmts of head
each has support cells and hair cells that extend to a gel like mass called cupula
dendrites of vestibular nerve encircle base of hair cells
99
dynamic eq activation
resp to changes in velocity of rotary head mvmts
directional bending of hair cells in cristae causes
depol, rapid impulses that reach the brain at a faster rate
hyper pol few impulses reach the brain
this informs brain of rotational info
100
main reason for motion sickness is
that visual input doesnt match eq input
101
vision
receptor by stimulus: photoreceptor
| location: retina
102
smell
receptor by stimulus: chemoreceptor
| location: olfactory epithelium; cilia
103
taste
receptor by stimulus: chemoreceptor
| location: taste buds; gustatory hairs
104
hearing
receptor by stimulus: mechanoreceptor
| location: organ of corti
105
static eq
receptor by stimulus: mechanorecptor
| location: vestibule-macule
106
dynamic eq
receptor by stimulus: mechanoreceptor
| location: semicircular canals-crista ampularis
