Ch 13 PNS Flashcards
1
Q
Provides links from and to world outside body
All neural structures outside brain
A
PNS
2
Q
the awareness of changes in the internal and external environment
A
sensation
3
Q
the conscious interpretation of those stimuli
A
perception
4
Q
part of sensory system serving body wall and limbs
A
somatosensory system
5
Q
sensory integration receives inputs from
A
Exteroceptors, proprioceptors, and interoceptors
6
Q
Levels of neural integration in sensory systems:
A
receptor, circuit, perceptual
7
Q
sensory receptors
A
receptor level
8
Q
processing in ascending pathways
A
circuit level
9
Q
processing in cortical sensory areas
A
perceptual level
10
Q
Specialized to respond to changes in stimuli
A
sensory receptors
11
Q
awareness of stimulus
A
sensation
12
Q
interpretation of meaning of stimulus
A
perception
13
Q
Classification of Receptors based on
A
Type of stimulus they detect
Location in body
Structural complexity
14
Q
respond to touch, pressure, vibration, and stretch
A
mechanoreceptors
15
Q
sensitive to changes in temperature
A
thermoreceptors
16
Q
respond to light energy (e.g., retina)
A
photoreceptors
17
Q
respond to chemicals (e.g., smell, taste, changes in blood chemistry)
A
chemoreceptors
18
Q
sensitive to pain-causing stimuli (e.g., extreme heat or cold, excessive pressure, inflammatory chemicals)
A
nociceptors
19
Q
Respond to stimuli arising outside body
Receptors in skin for touch, pressure, pain, and temperature
Most special sense organs
A
exteroceptors
20
Q
Respond to stimuli arising in internal viscera and blood vessels
Sensitive to chemical changes, tissue stretch, and temperature changes
Sometimes cause discomfort but usually unaware of their workings
A
interoceptors
21
Q
Respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles
Inform brain of one’s movements
A
proprioceptors
22
Q
Tactile sensations (touch, pressure, stretch, vibration), temperature, pain, and muscle sense Modified dendritic endings of sensory neurons
A
simple receptors for general senses
23
Q
Vision, hearing, equilibrium, smell, and taste
A
receptors for special senses
24
Q
simple receptors for general senses are split into
A
Either nonencapsulated (free) or encapsulated
25
Abundant in epithelia and connective tissues
Most are nonmyelinated, small-diameter group C fibers; distal endings have knoblike swellings
Respond mostly to temperature and pain; some to pressure-induced tissue movement; itch
nonencapsulated (free) nerve endings
26
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Cold receptors (10–40°C); in superficial dermis
Heat receptors (32–48°C); in deeper dermis
Outside those temperature ranges, nociceptors activated pain
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thermoreceptors
27
Player in detection – vanilloid receptor
Ion channel opened by heat, low pH, chemicals, e.g., capsaicin (red peppers)
Respond to:
Pinching, chemicals from damaged tissue, capsaicin
nociceptors
28
Tactile (Merkel) discs
Hair follicle receptors
nonencapsulated
light touch receptors
29
joint position and motion
Joint kinesthetic receptors
30
stretch in tendons
tendon organs
31
muscle stretch
muscle spindles
32
deep continuous pressure
Bulbous corpuscles (Ruffini endings)
33
deep pressure and vibration
Lamellar (Pacinian) corpuscles
34
discriminative touch
Tactile (Meissner's) corpuscles
35
Twelve pairs of nerves associated with brain
cranial nerves
36
Sensory nerves of smell
Run from nasal mucosa to olfactory bulbs
Pass through cribriform plate of ethmoid bone
Purely sensory (olfactory) function
I Olfactory Nerves
37
Arise from retinas; really a brain tract
Pass through optic canals, converge and partially cross over at optic chiasma
Optic tracts continue to thalamus, where they synapse
Purely sensory (visual) function
II Optic Nerves
38
Fibers extend from ventral midbrain through superior orbital fissures to four of six extrinsic eye muscles
Function in raising eyelid, directing eyeball, constricting iris (parasympathetic), and controlling lens shape
III Oculomotor Nerves
39
Fibers from dorsal midbrain enter orbits via superior orbital fissures to innervate superior oblique muscle
Primarily motor nerve that directs eyeball
IV Trochlear Nerves
40
Largest cranial nerves; fibers extend from pons to face
Three divisions
Ophthalmic (V1) passes through superior orbital fissure
Maxillary (V2) passes through foramen rotundum
Mandibular (V3) passes through the foramen ovale
Convey sensory impulses from various areas of face (V1) and (V2)
Supply motor fibers (V3) for mastication
V Trigeminal Nerves
41
Fibers from inferior pons enter orbits via superior orbital fissures
Primarily a motor nerve, innervating lateral rectus muscle
VI Abducens
42
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Fibers from pons travel through internal acoustic meatuses, and emerge through stylomastoid foramina to lateral aspect of face
Chief motor nerves of face with 5 major branches
Motor functions include facial expression, parasympathetic impulses to lacrimal and salivary glands
Sensory function (taste) from anterior two-thirds of tongue
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VII Facial
43
Afferent fibers from hearing receptors (cochlear division) and equilibrium receptors (vestibular division) pass from inner ear through internal acoustic meatuses, and enter brain stem at pons-medulla border
Mostly sensory function; small motor component for adjustment of sensitivity of receptors
Formerly auditory nerve
VIII Vestibulocochlear
44
activate skeletal muscle
somatic reflexes
45
activate visceral effectors
autonomic reflexes
46
Integration center in spinal cord
| Effectors are skeletal muscle
spinal somatic reflexes
47
to smoothly coordinate skeletal muscle, nervous system must receive proprioceptor input regarding
Length of muscle
From muscle spindles
Amount of tension in muscle
From tendon organs
48
Maintains muscle tone in large postural muscles, and adjusts it reflexively
stretch reflex
49
Causes muscle contraction in response to increased muscle length
stretch reflex
50
how does the stretch reflex work
Stretch activates muscle spindle
Sensory neurons synapse directly with motor neurons in spinal cord
motor neurons cause stretched muscle to contract
51
all stretch reflexes are ________ and _______
monosynaptic and ipsilateral
52
IIa fibers synapse with interneurons that inhibit motor neurons of antagonistic muscles
reciprocal inhibition
53
positive stretch reflex indicate
Sensory and motor connections between muscle and spinal cord intact
Strength of response indicates degree of spinal cord excitability
54
if peripheral nerve damage or ventral horn injury
hypoactive or absent
55
if lesions of corticospinal tract
hyperactive
56
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Initiated by painful stimulus
Causes automatic withdrawal of threatened body part
Ipsilateral and polysynaptic
Protective; important
Brain can override
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flexor reflex
57
Occurs with flexor reflexes in weight-bearing limbs to maintain balance
Consists of ipsilateral withdrawal reflex and contralateral extensor reflex
crossed extensor reflex
58
Elicited by gentle cutaneous stimulation
| Depend on upper motor pathways and cord-level reflex arcs
superficial reflexes
59
most common superficial reflexes
Plantar reflex
| Abdominal reflex
60
Damage to motor cortex or corticospinal tracts and abnormal response
babinskis sign
61
Test integrity of cord from L4 through S2
Stimulus – stroke lateral aspect of sole of foot
Response – downward flexion of toes
plantar reflex
62
Test integrity of cord from T8 through T12
Cause contraction of abdominal muscles and movement of umbilicus in response to stroking of skin
Vary in intensity from one person to another
Absent when corticospinal tract lesions present
abdominal reflexes
63
what are the special senses
```
Vision
Taste
Smell
Hearing
Equilibrium
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64
what percent of the body's sensory receptors in eye
70
65
what are the three layers of the wall of the eye
Fibrous
Vascular
Inner
66
Internal cavity filled with fluids called
humors
67
Lens separates internal cavity into what
anterior and posterior segments
68
Outermost layer of eye; dense avascular connective tissue
| Two regions
fibrous layer
69
two regions of fibrous layer are what
sclera and cornea
70
Opaque posterior region
Protects, shapes eyeball; anchors extrinsic eye muscles
Continuous with dura mater of brain posteriorly
sclera
71
Transparent anterior 1/6 of fibrous layer
Bends light as it enters eye
Sodium pumps of corneal endothelium on inner face help maintain clarity of cornea
Numerous pain receptors contribute to blinking and tearing reflexes
cornea
72
Middle pigmented layer
| Three regions
vascular layer
73
what are the three regions of the vascular layer
choroid, ciliary body, and iris
74
Posterior portion of uvea; contains blood vessels
Supplies blood to all layers of eyeball
Brown pigment absorbs light to prevent light scattering and visual confusion
choroid
75
Ring of tissue surrounding lens
Smooth muscle bundles control lens shape
Capillaries of processes secrete fluid
Ciliary zonule (suspensory ligament) holds lens in position
ciliary body
76
Colored part of eye
iris
77
central opening that regulates amount of light entering eye
pupil
78
Originates as outpocketing of brain
| Delicate two-layered membrane
inner layer/retina
79
outer layer of inner layer
Single-cell-thick lining
Absorbs light and prevents its scattering
Phagocytosis of photoreceptor cell fragments
Stores vitamin A
pigmented layer
80
Signals spread from photoreceptors to bipolar cells to ganglion cells
Ganglion cell axons exit eye as optic nerve
Transparent
Composed of three main types of neurons
inner layer of retina
neural layer
81
what are the types of neurons in neural layer
Photoreceptors, bipolar cells, ganglion cells
82
Site where optic nerve leaves eye
| Lacks photoreceptors
optic disc/blind spot
83
two types of photoreceptors
rods and cones
84
Dim light, peripheral vision receptors
More numerous, more sensitive to light than cones
No color vision or sharp images
Numbers greatest at periphery
rods
85
Vision receptors for bright light
High-resolution color vision
Macula lutea exactly at posterior pole
cones
86
Tiny pit in center of macula with all cones; best vision
fovea centralis
87
The lens and ciliary zonule separate eye into two segments
anterior and posterior segments
88
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Transmits light
Supports posterior surface of lens
Holds neural layer of retina firmly against pigmented layer
Contributes to intraocular pressure
Forms in embryo; lasts lifetime
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vitreus humor
89
posterior segment contains ______ ______
vitreus humor
90
Anterior segment composed of two chambers
posterior and anterior chambers
91
between cornea and iris
anterior chamber
92
between iris and lens
posterior chamber
93
Anterior segment contains
aqueous humor
94
blocked drainage of aqueous humor increases pressure and causes compression of retina and optic nerve blindness
glaucoma
95
Biconvex, transparent, flexible, and avascular
Changes shape to precisely focus light on retina
Two regions:
lens
96
two regions of lens
lens fibers(bulk of lens) and lens epithelium
97
(clouding of lens) consequence of aging, diabetes mellitus, heavy smoking, frequent exposure to intense sunlight
cataracts
98
Eyes best adapted for _______ _______
distant vision
99
close vision Requires eye to make active adjustments using three simultaneous processes
Accommodation of lenses
Constriction of pupils
Convergence of eyeballs
100
Changing lens shape to increase refraction
| Near point of vision
accomodation
101
loss of accommodation over age 50
presbyopia
102
Accommodation pupillary reflex constricts pupils to prevent most divergent light rays from entering eye
constriction
103
Medial rotation of eyeballs toward object being viewed
convergence
104
Focal point in front of retina, e.g., eyeball too long
Corrected with a concave lens
nearsightedness
myopia
105
farsightedness
Focal point behind retina, e.g., eyeball too short
Corrected with a convex lens
hyperopia
106
Unequal curvatures in different parts of cornea or lens
| Corrected with cylindrically ground lenses or laser procedures
astigmatism
107
smell
olfaction
108
taste
gustation
109
Chemoreceptors respond to chemicals in _____ ______
aqueous solution
110
olfactory sensory neurons have ______ ______ _____
unusual bipolar neurons
111
how many odors can humans distinguish
10,000
112
how many smell genes active in nose?
1000
113
Activation of olfactory sensory neurons
Dissolved odorants bind to receptor proteins in olfactory cilium membranes
114
taste buds are _____ ____
receptor organs
115
what are the five basic sensations of taste
BUSS: bitter, umami, sweet, sour, salt
116
sugars, saccharin, alcohol, some amino acids, some lead salts
sweet
117
hydrogen ions in solution
sour
118
metal ions (inorganic salts)
salty
119
alkaloids such as quinine and nicotine; aspirin
bitter
120
amino acids glutamate and aspartate
umami
121
Possible sixth taste
lipids
122
tastes/dislikes have
homeostatic value, genetic, and protective
123
To be tasted, chemicals must
Be dissolved in saliva
Diffuse into taste pore
Contact gustatory hairs
124
three major areas of the ear
external. inner, middle
125
hearing only
external(outer), and middle (tympanic)
126
hearing and equilibrium
internal
127
composed of Helix (rim); lobule (earlobe)
| Funnels sound waves into auditory canal
auricle(pinna)
128
Short, curved tube lined with skin bearing hairs, sebaceous glands, and ceruminous glands
Transmits sound waves to eardrum
external acoustic meatus(auditory canal)
129
Boundary between external and middle ears
Connective tissue membrane that vibrates in response to sound
Transfers sound energy to bones of middle ear
tympanic membrane(eardrum)
130
A small, air-filled, mucosa-lined cavity in temporal bone
Flanked laterally by eardrum
Flanked medially by bony wall containing oval (vestibular) and round (cochlear) windows
middle ear (tympanic cavity)
131
Three small bones in tympanic cavity
ear ossicles: Malleus, incus, stapes
132
two major divisions of internal ear
bony labyrinth and membranous labyrinth
133
Tortuous channels in temporal bone
Three regions
Filled with perilymph – similar to CSF
bony labyrinth
134
three regions of bony labyrinth
vestibule, semicircular canals, and cochlea
135
Series of membranous sacs and ducts
| Filled with potassium-rich endolymph
membranous labyrinth
136
Pressure disturbance (alternating areas of high and low pressure) produced by vibrating object
sound
137
Moves outward in all directions
| Illustrated as an S-shaped curve or sine wave
sound wave
138
Number of waves that pass given point in given time
| Pure tone has repeating crests and troughs
frequency
139
Distance between two consecutive crests
wavelength
140
Shorter wavelength = what
higher frequency of sound
141
Perception of different frequencies
| Normal range 20–20,000 hertz (Hz)
pitch
142
Higher frequency = what
higher pitch
143
Most sounds are mixtures of different frequencies
| Richness and complexity of sounds (music)
quality
144
Height of crests
amplitude
145
Amplitude perceived as ______
loudness
146
Severe hearing loss with prolonged exposure above
90dB
147
Normal range of loudness
0–120 decibels (dB)
148
Equilibrium receptors in semicircular canals and vestibule
Vestibular receptors monitor static equilibrium
Semicircular canal receptors monitor dynamic equilibrium
vestibular apparatus
149
Sensory receptors for static equilibrium
One in each saccule wall and one in each utricle wall
Monitor the position of head in space, necessary for control of posture
Respond to linear acceleration forces, but not rotation
Contain supporting cells and hair cells
maculae
150
Each crista has supporting cells and hair cells that extend into gel-like mass called
ampullary cupula
151
Sensory receptor for rotational acceleration
One in ampulla of each semicircular canal
Major stimuli are rotational movements
crista ampullares
152
Bending of hairs in cristae causes
Depolarizations, and rapid impulses reach brain at faster rate
153
Strange eye movements during and immediately after rotation
vestibular nystagmus
