M3 U2 Special Senses Flashcards
optically equivalent to the usual photographic camera
eye
eye components related to camera
lens system,
a variable aperture system (the pupil),
a retina that corresponds to the film.
three processes vision
the refraction or bending of light by the
lens and cornea
accommodation, the change in shape of
the lens
constriction or narrowing of the pupil
bending of light rays at an angulated
interface
refraction.
The direction in which light travels is always
____ to the plane of the wave
front, the direction of travel of the light
beam bends___.
perpendicular
downward
of the total refraction of light
occurs at the cornea.
75%
Increase in the curvature of the lens for near
vision
“focusing”
ACCOMODATION
attach radially around the lens, pulling the
lens edges toward the outer circle of the
eyeball. These ligaments are constantly
tensed, causing the lens to remain relatively
flat under normal conditions of the eye.
Suspensory ligaments
- Laterally attached to the suspensory
ligaments. Arranged circularly around the
ligaments so that when they contract, a
sphincter-like action occurs, decreasing the
diameter of the circle of ligament attachments.
Ciliary muscle
Loss of accommodation by the lens
PRESBYOPIA
can sufficiently refract light rays from an object 6
m (20 ft ) away so that a clear image is focused on
the retina.
the emmetropic eye can see all distant objects
clearly with its ciliary muscle relaxed.
Emmetropia (Normal Vision)
also known as hypermetropia
Parallel light rays focus behind the retina
Hyperopia (Farsightedness)
when the ciliary muscle is completely relaxed, the
light rays coming from distant objects are focused in
front of the retina
Myopia (Nearsightedness)
refractive error of the eye that
causes the visual image in one plane to focus at a
different distance from that of the plane at right
angles.
Astigmatism
an especially common eye abnormality
that occurs mainly in older people.
cloudy or opaque area or areas in the lens
cataract
- The ability to determine distance
DEPTH PERCEPTION
occurs when light rays
from an object strike corresponding points
on the two retinas.
Binocular vision
Lazy eye
Misalignment of the eyes
May cause blurred vision
AMBLYOPIA
involves the neurons in the successive
stages of the visual chain in the retina
itself and in the brain.
Neural adaptation
specialized cells in the photoreceptor layer in
the retina that begin the process by which light
rays are ultimately converted to nerve
impulses.
Photoreceptors
allow us to see in dim light, such as moonlight.
Because rods do not provide color vision, in dim
light we can see only black, white, and all shades
of gray in between
Rods
- produce color vision. Three cones are present in
the retina: blue cones, green cones, and red cones.
Each type of cone are sensitive to their respective
color of light.
Cones
is created by vibrations that may occur in
air, fluid, or solid material.
Sound
the perceived loudness or softness of
sound. The height, or amplitude of a sound wave
determines its volume.
Volume
number of sound waves that occur
during a specific time unit (frequency)
Pitch
directs sound waves into the external auditory canal
auricle
strike the tympanic membrane and cause it to vibrate.
Sound waves
Caused by impairment of the
cochlea, the auditory nerve, or the
central nervous system circuits from
the ear
Nerve deafness
Caused by impairment of the
physical structures of the ear that
conduct sound itself to the cochlea
Conduction deafness
progressive hearing loss
associated with againg resulting from
degeneration of nerve tissue in the ear and
the vestibulocochlear nerve
Presbycusis
help prevent damage to hearing
cause by prolonged loud noise
tensor tempani and
stapedius
a chronic inner ear disease of
unknown cause.
Meniere’s disease,
distension of membranous labyrinth by the endolymph,
endolymphatic hydrops
The most obvious cause is blockage of the external auditory canal. Waxy buildup of
cerumen commonly blocks conduction of sound toward the tympanic membrane.
Foreign objects,
Conduction deafness
an inherited bone disorder that impairs conduction by causing structural irregularities in the stapes.
Otosclerosis
often produces swelling and pus formation that block the conduction of sound through the middle ear. Permanent damage to structures of the middle ear
occasionally occurs in severe cases.
Otitis media
the perception of noise or ringing in the ears
Tinnitus
used to determine the nature of hearing disabilities
audiometer
the receptor organs for equilibrium are
called the
Vestibular Apparatus;
A function needed to sense the position of the head relative to gravity or to sense acceleration or deceleration of the body, as would occur when seated motionless in a vehicle that was increasing or decreasing in speed.
Static Equilibrium
A function needed to maintain balance when the head or body itself is rotated or suddenly moved.
Dynamic equilibrium
bipolar neurons (one axon, one dendrite) that contain the olfactory cilia, hair like projections that have the receptors that are stimulated by
the odorants.
Olfactory receptor cells
columnar epithelial cells that provide physical support, nourishment, insulation to the olfactory receptor cells. They also provide protection by detoxifying chemicals that come in contact with the olfactory epithelium.
Supporting cells
–stem cells that continually divide to produce
new olfactory receptor cells
Basal cells
epithelium lining the nasal cavity, although they do not participate directly in odor determination, they are important to note since they are the ones producing mucus that keeps the nasal cavity moist.
Olfactory gland or Bowman’s gland
The temporary inability to distinguish a
particular odor after prolonged exposure to the
airborne chemical compound.
Olfactory fatigue
The temporary inability to distinguish a
particular odor after prolonged exposure to the
airborne chemical compound.
Olfactory fatigue
these have microvilli
(hair like projections) that picks up the chemical
stimuli from anything ingested
Gustatory receptor cells
these cells bring physical support
to the gustatory receptor cells. They can also
become new receptor cells when needed
Gustatory Supporting cells
stem cells located the base which
produce new supporting cells.
Gustatory Basal cells
