6 Senses Terminology

general senses

temperature, pain, touch, pressure, vibration, proprioception, found all over the body, simple receptors

special senses

vision, hearing, taste, smell, equilibrium,

concentrated within a specific, complex structure at specific places in the body

sensation

what occurs when a stimulus activates a receptor, produces an action potential, and then that information arrives at the CNS.

perception

the process of interpreting sensory information, being consciously aware of a sensation

adaptation

reduced sensitivity in the presence of a constant stimulus.

olfaction

sense of smell, chemoreceptors

gustation

sense of taste, chemoreceptors

equilibrium

sense of balance, rotational and static

retina

the light-sensitive layer of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

cornea

transparent curved portion of the fibrous layer of the eye, most superficial structure

accommodation

the process by which the lens changes shape to focus near or far objects on the retina

choroid

middle, vascular layer of the eye, between the retina and the sclera

optic disc

Region at the back of the eye where the optic nerve meets the retina. It is the blind spot of the eye because it contains only nerve fibers, no rods or cones, and is thus insensitive to light.

fovea

area consisting of a small depression in the retina containing the highest concentration of cones and where vision is most acute

cones

retinal receptor cells that detect fine detail in bright light and give rise to color vision.

rods

retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond.

cataract

clouding of the lens of the eye

sclera

White, fibrous outer layer of the eyeball

vitreous humor

jelly like material that maintains eye shape and optical properties

otolith

a calcium carbonate particle in the vestibule of the inner ear, ear stone, moves hair cells when acted upon by gravity

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

endolymph

fluid within the semicircular canals, used in sense of balance

perilymph

fluid that is inside the cochlea, used in sense of hearing

semicircular canals

three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with rotational movement

vestibule

inner ear structure for gravity and linear acceleration

hair cells

mechanoreceptors in the inner ear for hearing and balance

eustachian tube (auditory tube)

tube connecting the middle ear to the pharynx (throat) that drains water from the ear, equalizes pressure

ossicles

three tiny bones in the middle ear -

malleus, incus, stapes, transmit mechanical vibrations to the inner ear

tympanic membrane

eardrum, collects sound waves for the purpose of hearing

conjunctiva

mucous membrane that lines eyelid and covers front of sclera; first defense against debris or foreign material

macular degeneration

breakdown or thinning of the tissues in the area around the fovea, resulting in partial or complete loss of central vision

accessory structures of the eye

eyelids, conjunctiva, lacrimal apparatus, oculomotor muscles

glaucoma

increased intraocular pressure results in damage to the retina and optic nerve with loss of vision

aqueous humor

watery fluid in the eye, found between the cornea and the lens, produced by ciliary body

tinnitus

ringing or buzzing in the ears

vitamin A and eyesight

- plays roles in the process of light perception at the retina and in the maintenance of a healthy, crystal-clear cornea, deficiency can lead to eye disorders

decibels (dB)

unit of measurement of volume (loudness)

hertz (Hz)

unit of measurement for frequency (pitch of sound)

rotational equilibrium

the perception of spinning movements, detected by hair cells due to endolymph movement of the cupula in the semi-circular canals

static equilibrium

the perception of the orientation of the head in a linear or vertical plane, detected by hair cells due to gravity's effect on the otolith of the vestibule

cupula

A gelatin-like structure containing hair cells (sensory receptor cells) in the semicircular canals.

iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

ciliary body and muscle

muscule which controls the shape of the lens and body produces the aqueous humor.

lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

myopia

nearsight; lack of clarity in far-off objects

hyperopia

farsighted; lack of clarity in nearby objects