Nervous System- Sensation Flashcards
(144 cards)
1
Q
Sensation
A
the conscious or subconscious awareness of changes in the external or internal environment
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
3
Q
general senses
A
somatic
visceral
4
Q
somatic sense
A
tactile sensations, thermal sensations, pain sensations, proprioceptive sensation
5
Q
visceral sense
A
info about conditions within internal organs
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
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
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
9
Q
structural classifications of nerve receptors
A
free nerve endings
encapsulated nerve endings
separate cells
10
Q
free nerve endings
A
simplest; bare dendrites that lack any structural specializations; pain, temperature, tickle, itch, and some touch sensations
11
Q
encapsulated nerve endings
A
dendrites are enclosed in a connective tissue capsule with a distinctive microscopic structure; some touch, pressure, and vibration
12
Q
separate cells
A
specialized cells that synapse with sensory neurons; hair cells in the inner ear
13
Q
functional classifications of nerve receptors (types of stimuli they detect)
A
mechanoreceptors thermoreceptors nocieptors photoreceptors chemoreceptors osmoreceptors
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
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
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
17
Q
photoreceptors
A
detect light that strikes the retina of the eye
18
Q
chemoreceptors
A
detect chemicals in the mouth (gustation), nose (olfaction), and body fluids
19
Q
osmoreceptors
A
detect the osmotic pressure of body fluids
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
21
Q
touch
A
receptors in the skin or subcutaneous layer
meissner corpuscles
hair root plexuses
merkel discs
ruffini corpuscles
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
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
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
25
ruffini corpuscles ( type II cutaneous mechanoreceptors)
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
26
pressure
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
27
Pacinian corpuscle (lamellated corpuscle)
rapidly adapting; large oval structure
composed of a multilayered connective tissue capsule that encloses a dendrite;
widely distributed in the body
28
vibration
result from rapidly repetitive sensory signals from tactile receptors
Meissner corpuscles – detect lower-frequency vibrations
Pacinian corpuscles – detect higher-frequency vibrations
29
itch
stimulation of free nerve endings by certain chemicals often because of local
inflammatory response
30
tickle
probably mediated by free nerve endings; cannot tickle oneself, probably because of action in the cerebellum when you are moving your own fingers
31
thermal
thermoreceptors
32
cold receptors
located in epidermis; activated by temperatures between 10-40 C
(50-105 F)
33
warm receptors
located in the dermis; activated by temperatures between 32-48
C (90-118 F)
34
pain
noicieptors
35
fast pain
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
36
slow pain
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
37
referred pain
when pain is felt in areas removed from the stimulus; usually served by the same segment of the spinal cord
38
Proprioceptive sensations
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
39
kinesthesia
the perception of body movements
40
propioceptors
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
41
opthalmology
the science that deals with the eye and its disorders
42
Otorhinolaryngology
the science that deals with the ears, nose, and throat and their disorders
43
olfaction
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
44
olfactory epithelium
upper portion of the nasal cavity
45
olfactory receptors
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
46
olfactory hairs
cilia that project from a knob-shaped tip on each olfactory receptor; respond to
inhaled chemicals
47
odorants
chemicals that have an odor and can therefore stimulate the olfactory hairs
48
supporting cells
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
49
basal stem cells
stem cells located between the bases of the supporting cells and continually undergo cell division to produce new olfactory receptors
50
olfactory glands
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
51
how many primary odors
100s, brain has the ability to recognize 10,000 different odors ( different combinations of primary odors)
52
olfactory ( I) nerve
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
53
olfactory bulbs
paired masses of gray matter located below the frontal lobes of the cerebrum; here, first order neurons synapse with second order neurons
54
olfactory tract
second order neurons leaving the olfactory bulbs form the olfactory tract; project to the primary olfactory area, the limbic system, and hypothalamus
55
primary olfactory area
temporal lobe where conscious awareness of olfaction begins
56
gustation
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
57
taste buds
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
58
papillae
elevations on the tongue where taste buds are found; provide a rough texture to the
upper surface of the tongue
59
vallate papillae
form an inverted V shaped row at the back of the tongue
60
fungiform papillae
mushroom shaped elevations scattered over the entire surface of the tongue
61
filiform papillae
on the entire surface of the tongue; contain touch receptors but no taste buds
62
tastant
a chemical that stimulates gustatory receptor cells; dissolves in saliva and enters taste
pores resulting in an electrical signal
63
vision
More than half the sensory receptors in the human body are located in the eyes
64
accessory structures
eyebrows and eyelashes
eyelids ( upper and lower_
extrinsic muscles
65
eyebrows and eyelashes
protect the eyeballs from foreign objects, perspiration, and direct rays of the sun
66
eyelids ( upper and lower)
shade the eyes during sleep, protect the eyes from excessive light and foreign objects, spread lubricating secretions over the eyeballs
67
extrinsic muscles
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
lacrimal appartus
a group of glands, ducts, canals, and sacs that produce and drain lacrimal fluid (tears)
69
lacrimal glands ( right and left)
each about the size and shape of an almond; secrete tears through lacrimal ducts onto the surface of the upper eyelid
70
lacrimal canals and nasolacrimal duct
allow the tears to drain into the nasal cavity
71
lysozyme
a bacteria-killing enzyme in tears
72
lacrimation
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
layers of the eyeball
fibrous tunic
vascular tunic
retina
74
fibrous tunic
the outer coat of the eyeball; consists of an anterior cornea and a posterior
sclera
cornera
sclera
conjunctiva
75
vascular tunic
middle layer of the eyeball composed of the choroid, ciliary body, and iris
```
choroid
ciliary body
lens
iris
pupil
```
76
choroid
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
ciliary body
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
lens
a transparent structure that focuses light rays onto the retina; constructed of many layers of elastic protein fibers
79
iris
the colored part of the eyeball including the circular and radial smooth muscle fibers
80
pupil
the hole in the center of the iris through which light enters the eyeball
81
retina
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
neural layer
multilayered outgrowth of the brain; photoreceptor layer, bipolar cell layer, and ganglion cell layer with inner and outer synaptic layers where synapses occur
83
pigmented layer
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
photoreceptors
specialized cells that begin the process by which light rays are ultimately converted to nerve impulses
rods
cones
85
rods
allow us to see shades of gray in dim light
86
cones
stimulated by brighter light, giving rise to highly acute color vision; blue cones, green cones, and red cones
87
optic (II) nerve
where the axons of the ganglion cells exit the retina
88
interior of the eyeball
divided into two cavities by the lens
anterior cavity
vitreous chamber
89
anterior cavity
anterior to the lens and filled with aqueous humor
aqueous humor
90
aqueous humor
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
vitreous chamber
larger cavity behind the lens; contains vitreous body
92
vitreous body
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
intraocular pressure
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
image formation
3 processes for the eye to form clear images on the retina
refraction or bending of light
change in shape of the lens
95
refraction or bending of light by the lens and cornea
75% takes place at the cornea, the
| rest is handled by the lens; images focused on the retina are inverted and reversed
96
refraction
the bending that takes place at the junction between two substances
as light passes through it
97
accommodation
increase in the curvature of the lens for near vision
98
emmetropic eye
normal eye
99
myopia
nearsightedness; eyeball is too long relative to focusing power, can only see near
100
hyperopia
farsightedness; eyeball is too short relative to focusing power, can aonly see far
101
astigmatism
either the cornea or the lens has an irregular curvature
102
constriction or narrowing of the pupil
narrowing of the diameter of the hole through which light enters the eye
103
binocular vision
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
convergence
the automatic movement of the two eyeballs toward the midline to focus on an object
105
vision pathway
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
Optic (II) nerve
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
saccades
rapid movements that shift the fovea to an object of interest
108
fovea
portion of the retina with the greatest visual acuity, where only cone receptors are located; center of the macula
109
smooth pursuit movements
slow and are used for tracking a moving object
110
vergence movements
(convergent or divergent) ensure that the image of an object of interest falls on the same place on the retina of each eye
111
vestibuloocular reflexes
use information from the semicircular canals to compensate for head motion by adjusting eye position to maintain the direction of gaze
112
optokinetic reflexes
use visual information to supplement the effects of the vestibuloocular reflex
113
3 main regions of the ear
external ear
middle ear
internal ear
114
external ear
collects sound waves and channels them inward
```
auricle
external auditory canal
cerminous glands
tympanic membrane
perforated eadruym
```
115
auricle
the part of the ear that you can see; skin-covered flap of elastic cartilage shaped
like the flared end of a trumpet
116
external auditory canal
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
cerminous glands
secrete cerumen (earwax)
118
tympanic membrane ( eardrum)
a thin semitransparent partition between the externalauditory canal and the middle ear; sound waves cause the eardrum to vibrate
119
perforated eardrum
tearing of the tympanic membrane due to trauma or infection
120
middle ear
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
auditory tube (eustachian tube)
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
auditory ossicles
3 tiny bones extending across the middle ear and attached to it by ligaments: malleus (hammer), incus (anvil), and stapes (stirrup)
123
oval window
thin bony partition between the middle and internal ear, where the inner
ear begins
124
internal (inner) ear
divided into the outer bony labyrinth and inner membranous labyrinth
houses the receptors for hearing and equilibrium
125
bony labrinth
a series of cavities in the temporal bone including the cochlea (audition) and the vestibule and semicircular canals (equilibrium); contains perilymph
126
perilymph
a fluid that surrounds the inner membranous labyrinth
127
cochlea
a bony spiral canal that resembles a snail’s shell; organ of audition
128
vestibule
the oval-shaped middle part of the bony labyrinth
129
semicircular canals
3; anterior and posterior are vertical, lateral is horizontal
130
membranous labyrinth
a series of sacs and tubes with the same general shape as the bony labyrinth; contains endolymph fluid
131
physiology of audition
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
vestibular apparatus
the receptor organs for equilibrium including the saccule, utricle, and membranous semicircular ducts
static
dynamic
133
static
maintenance of the position of the body relative to the force of gravity; tilting the
head or linear acceleration/deceleration (elevator or car)
134
uricle and saccule
two sacs inside the membranous labyrinth in the vestibule;these trigger nerve impulses in the vestibular branch of the vestibulocochlear
(VIII) nerve
macula
135
macula
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
dynamic
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
semicircular ducts
3 portions inside the membranous labyrinth inside the bony semicircular canals; lie at right angles to one another in 3 planes
138
equilibrium pathways
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
anosmia
total lack of the sense of olfaction
140
detached retina
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
nystagmus
a rapid involuntary movement of the eyeballs, possibly caused by a disease of the central nervous system; associated with conditions that cause vertigo
142
otalgia
Earache
143
tinnitus
a ringing, roaring, or clicking in the ears
144
vertigo
A sensation of spinning or movement in which the world seems to revolve or the person seems to revolve in space
