55 terms

Unit 08 Special Senses

Vision, hearing, taste, smell, and balance
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cochlea
Snail-shaped chamber of the bony labyrinth that houses the receptor for hearing (the organ of Corti)
cerumen
Earwax; made by ceruminous glands (modified apocrine sweat glands)
gustation
Taste
otolith
One of the small calcified masses in the utricle and saccule of the inner ear
taste buds
Sensory receptor organs that house gustatory cells, which respond to dissolved food chemicals
auditory ossicles
The three tiny bones serving as transmitters of vibrations and located within the middle ear: the malleus, incus, and stapes
cornea
Transparent anterior portion of the eyeball; part of the fibrous tunic
rods
One of the two types of photosensitive cells in the retina; Function in dim light conditions.
astigmatism
A condition in which unequal curvatures in different parts of the lens (or cornea) of the eye lead to blurred vision
choroid
The vascular middle tunic of the eye
conjunctiva
Thin, protective mucous membrand lining the eyelids and covering the anterior surface of the eye itself
cones
One of the two types of photoreceptor cells in the retina of the eye; provide for color vision
aqueous humor
Watery fluid in the anterior chambers of the eye
hyperopia
A condition in which visual images are routinely focused behind the retina; commonly known as farsightedness
sclera
White opaque portion of the fibrous tunic of the eyeball
retina
Neural tunic of the eyeball; contains photoreceptors (rods, cones)
myopia
A condition in which visual images are focused in front of rather than on the retina; nearsightedness
pupil
Opening in the center of the iris through which light enters the eye
vitreous humor
The gel-like substance that reinforces the eyeball and prevents it from collapsing inward is the:
photopupillary reflex
Eyes suddenly exposed to bright light experience:
tarsal glands
Glands associated with the edges of the eyelids that secrete oil; modified sebaceous glands
vestibule
Static equilibrium receptors housed here
semicircular canals
three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with body movement; dynamic equilibrium
glaucoma
increased pressure in the eyeball due to obstruction of the outflow of aqueous humor
cataract
clouding of the natural lens of the eye
rhodopsin
A visual pigment consisting of retinal and opsin. When rhodopsin absorbs light, the retinal changes shape and dissociates from the opsin, after which it is converted back to its original form.
20-20,000 Hertz
range of human hearing
fovea centralis
area consisting of a small depression in the retina containing cones and where vision is most acute
ciliary body
the part of the eye that connects the iris to the choroid. It consists of the ciliary muscle (for accommodation), a series of radial ciliary processes (from which the lens is suspended by ligaments), and the ciliary ring (which adjoins the choroid).
chemoreceptors
detect molecules in solution that are smelled or tasted
proprioceptors
in muscles and joints it provides information on changes in physical position; golgi tendon organs and muscle spindles
thermoreceptors
detect changes in temperature
mechanoreceptors
a sensory receptor that responds to mechanical disturbances; hearing and balance receptors; also includes touch and pressure receptors
oval window
membrane that covers the opening between the middle ear and inner ear; stapes pushes against this membrane
dynamic equilibrium
Information about head movement especially rotation; semicircular canals
static equilibrium
maintenance of balance when the head and body are motionless; utricle and saccule within saccule
photopsin
visual pigment of cones; consists of same retinal found in rods and 3 different opsin proteins which respond to 3 different light wavelengths
accommodation
automatic adjustment in focal length of the lens of the eye; changing the shape of the lens
ceruminous glands
found only in the external ear canal, where their secretion combines with sebum and dead epidermal cells to form earwax, or cerumen.
convergence
ability to turn the eyes inward toward the nose to ensure only a single image of close objects is seen
emmetropia
normal vision
extrinsic (external) eye muscles
voluntary eye muscles; rectus and oblique muscles of the eye
intrinsic eye muscles
involuntary eye muscles; includes the iris (2 sets) and clilary body
lacrimal glands
gland above the eye; continually lubricates the eye with tears
optic chiasma
location where the optic nerve fibers cross in the brain
optic disc (blind spot)
region of the retina where the optic nerve leaves the eye
organ of Corti
organ located in the cochlea; contains receptors (hair cells) that receive vibrations and generate nerve impulses for hearing
pharyngotympanic (auditory) tube
runs downward to link the middle ear cavity with the throat, swallowing and yawning opens it to equalize pressure in middle ear
photoreceptors
light-sensitive cells in the retina- the rods and cones
presbyopia
farsightedness caused by aging
presbycusis
age-related hearing loss
round window
membrane-covered opening in the inner wall of the middle ear that compensates for changes in cochlear pressure
scleral venous sinus (canal of Schlemm)
structure that is responsible for reabsorption of aqueous humor; blockage results in glaucoma
tympanic membrane (eardrum)
cone shaped semitransparent membrane attached to malleus; ear drum
vestibulocochlear nerve
cranial nerve VIII; balance and sound sensory information; afferent
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