bio 30 chp 14: ears and eyes

sensory adaptation and example

-sensory receptors/neurons adjust to stimulus in the environment

-neurons cease to fire even though stimulus is present

ex: wearing clothes

taste- detects __ chemicals

dissolved

smell- detects ___ chemicals

airborne

sclera

outmost layer

eye shape

protection

cornea

window to bend light towards pupil

clear cells layer

need oxygen from tearsand nutrients from the aqueous humor.

choroid layer

middle layer

pigmented to prevent light from scattering

blood vessels

iris

allows light into the eye

thin muscle

controls size of pupils

lens

focuses image onto retina

ciliary muscles

attach to ligaments in lens to alter shape

retina

innermost layer

rods and cones

rods

black n white

sensitive to light

see in dark

low definition

periphereal vision

cones

colour sensitive (red blue green)

high definition,

see in bright light

low sensitivity to light'

concentrated in Fovea Centralis

fovea centralis

most sensitive

small depression

most cones

rods on perimeter

blind spot

optic nerve and blood vessels connecting to eye

no room for photoreceptors

cataracts + solution

lens becomes opaque

prevent light from passing through, leading to blurred vision.

solution: remove lens, strong eyeglasses

glaucoma

buildup of aqueous humour in eye

blocked drainage duct ==> retinal cells die from pressure

vision loss

astigmatism

lens or cornea irregular shaped

colourblindness

lack certain cones

2 parts of the outer ear + functions

pinna: funnel sound to canal

auditory canal: funnel sound to ear drum, ear wax

middle ear 3 parts + function

• air filled; sound travels through solid bone

ossicles: amplify +passes sound from eardrum to oval window

Eustachian tube: lets air pressure equalize

tympanic membrane/eardrum : separate outer ear from middle ear