EYES Flashcards
(15 cards)
tell me about rods and cones?
rods= - senstive in dim light
- see images in black and white
- good in dark
cones = - senstive in bright light
- see images in color
- good in light condtions
they are also the receptors cells
where is the location of cones and rods?
retina
where is retina located?
in the back of the eye, inside of it
tell me about the fovea?
- center of retina
-where cones are densley concentrated
-rods are scattered further out of the retina
tell me about the optic nerve?
- receptor cells (rods + cones+) send impulses through sensory neurones to the brain
- sensory neurones gather and leave the eye through optic nerve (blind spot)
describe choroid?
- black pigmented tissue behind retina
- lines inside of eye
- absorps light to avoid reflection of light inside eye
describe sclera?
- white tough outer tissue
- lines outside of eye
-protects eye from damage
what happens in bright light?
- CIRCULAR MUSCLES CONTRACT
-RADIAL MUSCLES RELAX = PUPIL IS CONSTRICTED (SMALLER)
what happens in dim light?
-CIRCULAR MUSCLES RELAX
-RADIAL MUSCLES CONTRACT = PUPIL IS DIALATED (LARGER)
what happens when eyes try to focus?
cornea = REFRACTS MOST OF LIGHT
lens = FINE TUNES FOR CLEAR FOCUS
= ACCOMODATION
what does flat lens do?
- refracts light rays weakly
-for FAR objects
what does rounded lens do?
- refracts light rays strongly
- for CLOSE objects
to focus on far objects?
1) CILLIARY MUSCLES RELAX
2) SUSPENSORY LIGAMENTS TIGHTENED
3) LENS FLAT AND THIN
To focus on close objects?
1) CILLIARY MUSCLES CONTRACT
2)SUSPENSORY LIGAMENTS LOOSEND
3) LENS BULGED AND ROUNDED
Tell me about tears
tear gland releases tears, which contain LYSOZYME an enzyme which break down bacterial cell walls
