Special Senses

senses of touch

temperature, pressure, pain

special senses

• smell

• taste

• sight

• hearing

• equilibrium (balance)

what percent of sensory receptors are in the eyes

70%

most of the eye is enclosed in a

bony orbit

accessory structures of the eye

• eyelids

• eyelashes

• conjuctiva

• lacrimal apparatus (terms)

• eye muscles

tarsal glands 

lubricate the eye

ciliary glands

lubricate

conjuctiva

membrane that lines the eyelids

lacrimal appartus

produces lacrimnal fluid

lacrimal canals

drain lacrimal fluid from eyes

nasolacrimal duct

empties lacrimal fluid into the nasal cavity

function of lacrimal apparatus

protects, moisten, lubricates the eye

lacrimnal fluid contains

salt and antibodies

extrinsic eye muscles

produce eye movements (excersize)

fibrous layer =

vascular layer=

sensory layer=

outside layer

middle layer

inside layer

sclera

white tissue layer

cornea

• allows for light to pass through

• the only human tissue that can be transplanted w/o rejection

pigment prevents

light from scattering

iris

regulates amount of light entering eye

pupil

rounded opening in iris

retina contains two layers, the receptor cells are

rods=

cones=

• gray tones (black/white tones)

• color

optic disk

blind spot

colorblindness is an issue with the

cones

cataracts

causes blindness in the affected eye, with haziness and disortientation

anterior segment

aqueous humor (watery-based substance)

viterous segment

vitreal humor (gel-like substance)

what do the humors do?

helps maintain intraocular pressure

external muscles control eye movement to

follow objects (why light is shone to the pupil to check dilation)

myopia

nearsighted

hyperopia

farsighted

night blindness

rod function (grey, black, and white tones. which is why it acts up at night)

glaucome

can cause blindness due to increasing pressure within the eye

the ear houses two senses

• hearing

• equilibrium

mechanoreceptors

picks up sound waves

external=

middle ear=

inner ear=

• outer ear

• tympanic cavity

• bony labyrinth

external ear

• hearing only

middle ear=

• hearing

• equilibrium

inner ear=

• hearing

• balance

anatomy of the inner ear

• cochlea

• vestibule

• semicircular canal

static equilibrium

balance while still

dynamic equilibrium

balance while moving

olfactory receptors are located

roof of nasal cavity

saccharine

sweet receptors

acids

sour receptors

alkaloids

bitter receptors

metal

salty receptors

strabismus

crossed eyes

presbyopia

“old vision”