The Senses Flashcards
Ch 34
Benefits of carnivores eyes?
- better judgement of distance
- better focus on prey
Benefits of herbivores eyes?
- wider field of vision
- better detection of predators
Functions of conjunctiva?
- protection against infections & irritants
- moistens & lubricates
Function of sclera (sclerotic coat)
holds eye in shape
Function of cornea?
lets light into the eye,
and bends it towards the retina
Function of choroid?
ensures there’s no internal reflection of light inside the eye
How does choroid absorb light in the eye?
contains black pigment called melanin
How does choroid nourish the eye?
contains blood vessels
Where are light receptors (rods & cones) located?
retina
Are there more rods or cones?
rods
What do rods detect?
black and white (vision)
What do cones detect?
colour (vision)
What light do rods work in?
dim light
What light do cones work in?
bright light
Where are rods found?
all over retina
Where are cones found?
mostly at fovea
Function of fovea?
images are focused/formed
Is blind spot sensitive to light?
no
Are there rods or cones or both in blind spot?
none
What leave the blind spot through part of retina?
nerve fibres
Nerve fibres leave through what in blind spot?
retina
Function of optic nerve?
transmits impulses from the eye to the brain
What happens if damage is done to optic nerve?
can’t transmit/no impulse
Shape of lens?
curved
Function of lens?
focus light on the retina
What is accommodation (in ciliary muscle)?
the changing of shape of lens in a reflection action
What is coloured part of the eye?
Iris
What does iris control?
amount of light entering the eye
Blue-eyed people have no what?
melanin
When iris contracts, pupil…?
dilates
When iris relaxes, pupil…?
constricts
Opening of iris is called?
pupil
What does pupil let into eye?
light
Why is pupil black?
light normally emerges from the inside of eye
3 reasons why having two eyes is good?
- depth perception
- increase visual field
- 3D vision
Function of aqueous humour?
holds front of eye in shape
What is aqueous humour?
salt solution
Function of vitreous humour?
gives shape to eye
How is the eye moved?
by use of six external muscles