Nervous System- Sensation Flashcards

1
Q

Sensation

A

the conscious or subconscious awareness of changes in the external or internal environment

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2
Q

Special sense

A

olfaction, gustation, vision, audition, and equilibrium

Complex sensory organs such as the eyes and ears

Allow us to detect changes in our environment

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3
Q

general senses

A

somatic

visceral

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4
Q

somatic sense

A

tactile sensations, thermal sensations, pain sensations, proprioceptive sensation

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5
Q

visceral sense

A

info about conditions within internal organs

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6
Q

4 conditions for a sensation to occur

A

A stimulus must activate a sensory receptor
-light, heat, pressure, mechanical energy, or
chemical energy

A sensory receptor converts the stimulus into an electrical signal which produces nerve impulses if the stimulus was sufficient

The nerve impulses are conducted along a neural pathway from the sensory receptor to the brain

A region of the brain must receive and integrate the nerve impulses into a sensation

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7
Q

perception

A

the conscious awareness and interpretation of sensations; primarily a function of cerebral
cortex

A given sensory neuron carries info for one type of sensation only

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8
Q

adaptation

A

a decrease in the strength of a sensation during a prolonged stimulus; a characteristic of most sensory receptors

Rapidly adapting receptors (phasic receptors) – adapt very quickly; specialized for signaling changes in stimuli; pressure, touch, and olfaction

Slowly adapting receptors (tonic receptors) – adapt slowly and continue to trigger nerve impulses as long as the stimulus persists; pain, body position, and chemical composition of the blood

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9
Q

structural classifications of nerve receptors

A

free nerve endings
encapsulated nerve endings
separate cells

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10
Q

free nerve endings

A

simplest; bare dendrites that lack any structural specializations; pain, temperature, tickle, itch, and some touch sensations

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11
Q

encapsulated nerve endings

A

dendrites are enclosed in a connective tissue capsule with a distinctive microscopic structure; some touch, pressure, and vibration

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12
Q

separate cells

A

specialized cells that synapse with sensory neurons; hair cells in the inner ear

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13
Q

functional classifications of nerve receptors (types of stimuli they detect)

A
mechanoreceptors
thermoreceptors
nocieptors
photoreceptors
chemoreceptors
osmoreceptors
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14
Q

machanoreceptors

A

sensitive to mechanical stimuli including deformation, stretching, bending
of cells; touch, pressure, vibration, proprioception, audition, and equilibrium; stretching of blood vessels and internal organs

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15
Q

thermoreceptors

A

detect changes in temperature

free nerve endings; rapidly adapting, but continue to generate nerve
impulses more slowly throughout a prolonged stimulus

cold receptors
warm receptors
Above and below these ranges stimulate mainly nociceptors

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16
Q

nociceptors

A

respond to painful stimuli resulting from physical or chemical damage to tissue

sensory receptors for pain; free nerve endings; in practically every tissue of
the body except the brain

Respond to several types of stimuli: excessive stimulation of sensory receptors, excessive stretching of a structure, prolonged muscular contractions, inadequate blood flow, presence of certain chemical substances

Pain may persist even after the stimulus is removed because pain-causing chemicals
linger and because nociceptors exhibit very little adaptation

fast pain

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17
Q

photoreceptors

A

detect light that strikes the retina of the eye

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18
Q

chemoreceptors

A

detect chemicals in the mouth (gustation), nose (olfaction), and body fluids

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19
Q

osmoreceptors

A

detect the osmotic pressure of body fluids

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20
Q

somatic senses

A

arise from stimulation of sensory receptors in the skin, mucous membranes, muscles, tendons, and joints

areas with largest numbers: tip of the tongue, the lips, and fingertips

tactile

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21
Q

touch

A

receptors in the skin or subcutaneous layer

meissner corpuscles
hair root plexuses
merkel discs
ruffini corpuscles

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22
Q

meissner corpuscles ( corpuscles of touch)

A

rapidly adapting touch receptors; located in the dermal papillae of hairless skin; fingertips, hands, eyelids, tip of the
tongue, lips, nipples, soles, clitoris, and tip of the penis

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23
Q

hair root plexuses

A

rapidly adapting touch receptors; found in hairy skin; free nerve endings wrapped around hair follicles; detect movements on the skin surface that disturb hairs

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24
Q

merkel discs ( type I cutaneous mechanoreceptors)

A

slowly adapting touch receptors; saucer-shaped, flattened free nerve endings; plentiful in fingertips, hands, lips, and external genitalia

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25
Q

ruffini corpuscles ( type II cutaneous mechanoreceptors)

A

slowly adapting touch
receptors; elongated encapsulated receptors deep in the dermis, ligaments, and tendons; hands and soles; most sensitive to stretching that occurs as digits or limbs are moved

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26
Q

pressure

A

sustained sensation that is felt over a larger area and occurs in deeper tissues
than touch; deformation of deeper tissues

Meissner corpuscles and Merkel discs contribute to sensation of pressure

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27
Q

Pacinian corpuscle (lamellated corpuscle)

A

rapidly adapting; large oval structure
composed of a multilayered connective tissue capsule that encloses a dendrite;
widely distributed in the body

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28
Q

vibration

A

result from rapidly repetitive sensory signals from tactile receptors

Meissner corpuscles – detect lower-frequency vibrations

Pacinian corpuscles – detect higher-frequency vibrations

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29
Q

itch

A

stimulation of free nerve endings by certain chemicals often because of local
inflammatory response

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30
Q

tickle

A

probably mediated by free nerve endings; cannot tickle oneself, probably because of action in the cerebellum when you are moving your own fingers

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31
Q

thermal

A

thermoreceptors

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32
Q

cold receptors

A

located in epidermis; activated by temperatures between 10-40 C
(50-105 F)

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33
Q

warm receptors

A

located in the dermis; activated by temperatures between 32-48
C (90-118 F)

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34
Q

pain

A

noicieptors

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35
Q

fast pain

A

perception occurs very rapidly; acute, sharp, or pricking; not felt in deeper tissues of the body; precisely localized

Needle puncture or knife cut to the skin

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36
Q

slow pain

A

perception begins a second or more after a stimulus is applied, then gradually
increases in intensity over a period of several seconds or minutes; chronic, burnings, aching, or throbbing; in the skin and in deeper tissues or internal organs; well localized but more diffuse

toothache

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37
Q

referred pain

A

when pain is felt in areas removed from the stimulus; usually served by the same segment of the spinal cord

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38
Q

Proprioceptive sensations

A

allow us to know where our head and limbs are located and how they are moving even if we are not looking at them, so that we can walk, type, or dress without using our eyes

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39
Q

kinesthesia

A

the perception of body movements

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40
Q

propioceptors

A

receptors located in skeletal muscles and tendons, in and around synovial joints, and in the inner ear that

Inform us of the degree to which muscles are contracted, the amount of tension on
tendons, and the positions of joints

Allow one to estimate the weight of objects and determine the muscular effort necessary to perform a task

Adapt slowly and only slightly to ensure coordination

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41
Q

opthalmology

A

the science that deals with the eye and its disorders

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42
Q

Otorhinolaryngology

A

the science that deals with the ears, nose, and throat and their disorders

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43
Q

olfaction

A

smell

Nose contains 10-100 million receptors for olfaction

Some nerve impulses for olfaction and gustation propagate to the limbic system which can evoke strong emotional responses and memories

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44
Q

olfactory epithelium

A

upper portion of the nasal cavity

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45
Q

olfactory receptors

A

first-order neurons of the olfactory pathway; live for only a month or so

Olfactory receptors adapt by about 50% in the first second or so after stimulation and very slowly thereafter

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46
Q

olfactory hairs

A

cilia that project from a knob-shaped tip on each olfactory receptor; respond to
inhaled chemicals

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47
Q

odorants

A

chemicals that have an odor and can therefore stimulate the olfactory hairs

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48
Q

supporting cells

A

columnar epithelial cells of the mucous membrane lining the nose; provide
physical support, nourishment, and electrical insulation for the olfactory receptors; help detoxify chemicals that come in contact with the olfactory epithelium

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49
Q

basal stem cells

A

stem cells located between the bases of the supporting cells and continually undergo cell division to produce new olfactory receptors

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50
Q

olfactory glands

A

produce mucus that moistens the surface of the olfactory epithelium and
serves as a solvent for inhaled odorants

The brain has the ability to recognize about 10,000 different odors (different combinations of primary odors)

Olfactory receptors adapt by about 50% in the first second or so after stimulation and very slowly thereafter

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51
Q

how many primary odors

A

100s, brain has the ability to recognize 10,000 different odors ( different combinations of primary odors)

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52
Q

olfactory ( I) nerve

A

about 40 bundles of slender unmyelinated axons of olfactory receptors that
extend through about 20 holes in the cribriform plate of the ethmoid bone; terminate in the brain in olfactory bulbs

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53
Q

olfactory bulbs

A

paired masses of gray matter located below the frontal lobes of the cerebrum; here, first order neurons synapse with second order neurons

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54
Q

olfactory tract

A

second order neurons leaving the olfactory bulbs form the olfactory tract; project to the primary olfactory area, the limbic system, and hypothalamus

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55
Q

primary olfactory area

A

temporal lobe where conscious awareness of olfaction begins

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56
Q

gustation

A

taste
only 5: sour, sweet, bitter, salty, and unami( meaty or savory)

flavors are combinations of the five primary tastes, plus olfactory and tactile sensations

Complete adaptation to a specific taste can occur in 1-5 minutes of continuous stimulation

Different tastes arise from activation of different groups of gustatory neurons

Facial (VII) nerve, glossopharyngeal (IX) nerve, vagus (X) nerve – propagate impulses to the medulla oblongata

From thalamus to the primary gustatory area – parietal lobe of the cerebral cortex; gives rise to
the conscious perception of gustation

From medulla, to limbic system and hypothalamus, and thalamus

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57
Q

taste buds

A

where receptors for taste are located; nearly 10,000 in a young adult on the tongue,
roof of the mouth, pharynx, and epiglottis; number declines with age

Each one consists of 3 types of epithelial cells: supporting cells, gustatory receptor cells (10 days), and basal cells

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58
Q

papillae

A

elevations on the tongue where taste buds are found; provide a rough texture to the
upper surface of the tongue

59
Q

vallate papillae

A

form an inverted V shaped row at the back of the tongue

60
Q

fungiform papillae

A

mushroom shaped elevations scattered over the entire surface of the tongue

61
Q

filiform papillae

A

on the entire surface of the tongue; contain touch receptors but no taste buds

62
Q

tastant

A

a chemical that stimulates gustatory receptor cells; dissolves in saliva and enters taste
pores resulting in an electrical signal

63
Q

vision

A

More than half the sensory receptors in the human body are located in the eyes

64
Q

accessory structures

A

eyebrows and eyelashes
eyelids ( upper and lower_
extrinsic muscles

65
Q

eyebrows and eyelashes

A

protect the eyeballs from foreign objects, perspiration, and direct rays of the sun

66
Q

eyelids ( upper and lower)

A

shade the eyes during sleep, protect the eyes from excessive light and foreign objects, spread lubricating secretions over the eyeballs

67
Q

extrinsic muscles

A

cooperate to move each eyeball right, left, up, down, and diagonally

Superior rectus, inferior rectus, lateral rectus, medial rectus, superior oblique, and
inferior oblique

68
Q

lacrimal appartus

A

a group of glands, ducts, canals, and sacs that produce and drain lacrimal fluid (tears)

69
Q

lacrimal glands ( right and left)

A

each about the size and shape of an almond; secrete tears through lacrimal ducts onto the surface of the upper eyelid

70
Q

lacrimal canals and nasolacrimal duct

A

allow the tears to drain into the nasal cavity

71
Q

lysozyme

A

a bacteria-killing enzyme in tears

72
Q

lacrimation

A

only humans express emotions by crying; parasympathetic stimulation,
lacrimal glands produce excessive tears that spill over the edges of the eyelids and fill the
nasal cavity with fluid

73
Q

layers of the eyeball

A

fibrous tunic
vascular tunic
retina

74
Q

fibrous tunic

A

the outer coat of the eyeball; consists of an anterior cornea and a posterior
sclera

cornera
sclera
conjunctiva

75
Q

vascular tunic

A

middle layer of the eyeball composed of the choroid, ciliary body, and iris

choroid
ciliary body
lens
iris
pupil
76
Q

choroid

A

a thin membrane that lines most of the internal surface of the sclera; contains many blood vessels that help nourish the retina and melanocytes that produce melanin which causes this layer to appear dark brown in color

77
Q

ciliary body

A

consists of the ciliary processes (folds on the inner surface), ciliary muscle (smooth muscle that alters the shape of the lens for near or far vision)

78
Q

lens

A

a transparent structure that focuses light rays onto the retina; constructed of many layers of elastic protein fibers

79
Q

iris

A

the colored part of the eyeball including the circular and radial smooth muscle fibers

80
Q

pupil

A

the hole in the center of the iris through which light enters the eyeball

81
Q

retina

A

third and inner coat of the eyeball; lines the posterior ¾ of the eyeball and is the
beginning of the visual pathway

neural layer
pigmented layer
photoreceptors

82
Q

neural layer

A

multilayered outgrowth of the brain; photoreceptor layer, bipolar cell layer, and ganglion cell layer with inner and outer synaptic layers where synapses occur

83
Q

pigmented layer

A

a sheet of melanin-containing epithelial cells located between the choroid and the neural part of the retina; helps to absorb stray light rays

84
Q

photoreceptors

A

specialized cells that begin the process by which light rays are ultimately converted to nerve impulses

rods
cones

85
Q

rods

A

allow us to see shades of gray in dim light

86
Q

cones

A

stimulated by brighter light, giving rise to highly acute color vision; blue cones, green cones, and red cones

87
Q

optic (II) nerve

A

where the axons of the ganglion cells exit the retina

88
Q

interior of the eyeball

A

divided into two cavities by the lens
anterior cavity
vitreous chamber

89
Q

anterior cavity

A

anterior to the lens and filled with aqueous humor

aqueous humor

90
Q

aqueous humor

A

a watery fluid similar to cerebrospinal fluid that helps maintain the shape of the eye and nourishes the lens and cornea; completely replaced every 90 min

91
Q

vitreous chamber

A

larger cavity behind the lens; contains vitreous body

92
Q

vitreous body

A

a clear, jellylike substance which forms during embryonic life and is not replaced thereafter; helps prevent the eyeball from collapsing and holds the retina flush against the choroid

93
Q

intraocular pressure

A

pressure in the eye produced mainly by the aqueous humor; maintains the shape of the eyeball and keeps the retina smoothly pressed against the choroid so the retina is well nourished and forms clear images

94
Q

image formation

A

3 processes for the eye to form clear images on the retina

refraction or bending of light
change in shape of the lens

95
Q

refraction or bending of light by the lens and cornea

A

75% takes place at the cornea, the

rest is handled by the lens; images focused on the retina are inverted and reversed

96
Q

refraction

A

the bending that takes place at the junction between two substances
as light passes through it

97
Q

accommodation

A

increase in the curvature of the lens for near vision

98
Q

emmetropic eye

A

normal eye

99
Q

myopia

A

nearsightedness; eyeball is too long relative to focusing power, can only see near

100
Q

hyperopia

A

farsightedness; eyeball is too short relative to focusing power, can aonly see far

101
Q

astigmatism

A

either the cornea or the lens has an irregular curvature

102
Q

constriction or narrowing of the pupil

A

narrowing of the diameter of the hole through which light enters the eye

103
Q

binocular vision

A

a characteristic of human eyes that allows both eyes to focus on only one set of objects; allows perception of depth and 3D nature of objects

104
Q

convergence

A

the automatic movement of the two eyeballs toward the midline to focus on an object

105
Q

vision pathway

A

After the rods and cones are stimulated by light, electrical signals are triggered in bipolar cells, then transmitted to ganglion cells

Ganglion cells become depolarized and generate nerve impulses

106
Q

Optic (II) nerve

A

the axons of the ganglion cells exit the eyeball and extend posteriorly to the optic chiasm (where they cross over), then to the thalamus

In the thalamus they synapse with neurons whose axons project to the primary visual
areas

107
Q

saccades

A

rapid movements that shift the fovea to an object of interest

108
Q

fovea

A

portion of the retina with the greatest visual acuity, where only cone receptors are located; center of the macula

109
Q

smooth pursuit movements

A

slow and are used for tracking a moving object

110
Q

vergence movements

A

(convergent or divergent) ensure that the image of an object of interest falls on the same place on the retina of each eye

111
Q

vestibuloocular reflexes

A

use information from the semicircular canals to compensate for head motion by adjusting eye position to maintain the direction of gaze

112
Q

optokinetic reflexes

A

use visual information to supplement the effects of the vestibuloocular reflex

113
Q

3 main regions of the ear

A

external ear
middle ear
internal ear

114
Q

external ear

A

collects sound waves and channels them inward

auricle
external auditory canal
cerminous glands
tympanic membrane
perforated eadruym
115
Q

auricle

A

the part of the ear that you can see; skin-covered flap of elastic cartilage shaped
like the flared end of a trumpet

116
Q

external auditory canal

A

a curved tube that extends from the auricle and directs sound waves toward the tympanic membrane; contains a few hairs and ceruminous glands that help prevent foreign objects from entering the ear

117
Q

cerminous glands

A

secrete cerumen (earwax)

118
Q

tympanic membrane ( eardrum)

A

a thin semitransparent partition between the externalauditory canal and the middle ear; sound waves cause the eardrum to vibrate

119
Q

perforated eardrum

A

tearing of the tympanic membrane due to trauma or infection

120
Q

middle ear

A

a small, air-filled cavity between the eardrum and the inner ear

divides inner from outer

auditory tube
auditory ossicles
oval window
conveys sound vibrations to the oval window

121
Q

auditory tube (eustachian tube)

A

connects the middle ear with the upper part of thethroat; when open, air pressure can equalize on both sides of the eardrum; when closed, if air pressure changes abruptly there may be a rupture

122
Q

auditory ossicles

A

3 tiny bones extending across the middle ear and attached to it by ligaments: malleus (hammer), incus (anvil), and stapes (stirrup)

123
Q

oval window

A

thin bony partition between the middle and internal ear, where the inner
ear begins

124
Q

internal (inner) ear

A

divided into the outer bony labyrinth and inner membranous labyrinth

houses the receptors for hearing and equilibrium

125
Q

bony labrinth

A

a series of cavities in the temporal bone including the cochlea (audition) and the vestibule and semicircular canals (equilibrium); contains perilymph

126
Q

perilymph

A

a fluid that surrounds the inner membranous labyrinth

127
Q

cochlea

A

a bony spiral canal that resembles a snail’s shell; organ of audition

128
Q

vestibule

A

the oval-shaped middle part of the bony labyrinth

129
Q

semicircular canals

A

3; anterior and posterior are vertical, lateral is horizontal

130
Q

membranous labyrinth

A

a series of sacs and tubes with the same general shape as the bony labyrinth; contains endolymph fluid

131
Q

physiology of audition

A

The auricle directs sound waves into the external auditory canal

Sound waves strike the eardrum and cause it to vibrate

The eardrum connects to the malleus which also starts to vibrate, then transmitted from the malleus to the incus and then to the stapes

The stapes moves back and forth and pushes the oval window in and out

The movement of the oval window creates waves in the perilymph of the cochlea, then in the endolymph inside the cochlear duct

The waves in the endolyph cause the basilar membrane to vibrate which stimulate the
vestibulocochlear (VIII) nerve where a nerve impulse is generated

The vestibulocochlear (VIII) nerve terminates in the medulla on the same side of the brain; axons ascend to the midbrain, then to the thalamus, and finally to the primary auditory area in the
temporal lobe
132
Q

vestibular apparatus

A

the receptor organs for equilibrium including the saccule, utricle, and membranous semicircular ducts

static
dynamic

133
Q

static

A

maintenance of the position of the body relative to the force of gravity; tilting the
head or linear acceleration/deceleration (elevator or car)

134
Q

uricle and saccule

A

two sacs inside the membranous labyrinth in the vestibule;these trigger nerve impulses in the vestibular branch of the vestibulocochlear
(VIII) nerve

macula

135
Q

macula

A

a small thickened region of the walls of both the utricle and the saccule that are perpendicular to one another; receptors for static equilibrium; provide sensory info on the position of the head in space and help maintain appropriate posture and balance

136
Q

dynamic

A

the maintenance of body position in response to rotational acceleration
or deceleration; shaking the head “no”

Detects rotational acceleration and deceleration

Trigger nerve impulses in the vestibular branch of the vestibulocochlear
(VIII) nerve

137
Q

semicircular ducts

A

3 portions inside the membranous labyrinth inside the bony semicircular canals; lie at right angles to one another in 3 planes

138
Q

equilibrium pathways

A

The vestibular branch axons of the vestibulocochlear (VIII) nerve enter the brain stem, then extend to the medulla or cerebellum where they synapse with the next neurons in the equilibrium pathways

Some axons conduct from the medulla along the cranial nerves that control eye movements and head and neck movements

Other axons form a spinal cord tract that conveys impulses for regulation of muscle tone in response to head movements

Various pathways enable the cerebellum to play a key role in maintaining equilibrium

139
Q

anosmia

A

total lack of the sense of olfaction

140
Q

detached retina

A

detachment of the neural portion of the retina from the pigment epithelium due to
trauma, disease, or age-related degeneration; the result is distorted vision and blindness

141
Q

nystagmus

A

a rapid involuntary movement of the eyeballs, possibly caused by a disease of the central nervous system; associated with conditions that cause vertigo

142
Q

otalgia

A

Earache

143
Q

tinnitus

A

a ringing, roaring, or clicking in the ears

144
Q

vertigo

A

A sensation of spinning or movement in which the world seems to revolve or the person seems to revolve in space