Topic 10: The Human Eye Flashcards
(19 cards)
Structure + Function
Conjunctiva
- thin transparent membrane
- protects the cornea at the front of the eyeball against friction
Structure + Function
Cornea
- anterior end of the sclera which forms a small bulge in front of the eye
- the transparent portion of the sclera; allowing light to pass through it to reach the retina
- refracts light into pupil (most of the refraction of light occurs here)
Structure + Function
Sclera
tough white outer layer of eyeball that protects the eyeball against any mechanical injury
Choroid
- contains blood vessels that is supplying the retina with oxygen and nutrients
- pigmented black to prevent internal reflection of light
Structure + Function
Retina
- innermost layer of the eyeball that contains photoreceptors (rods and cones) that detect stimuli
- cones are concerned with color vision in bright light
- rods are concerned with vision in dim light
Structure + Function
Optic Nerve
transmits nerve impulses (information) from photoreceptors to the
brain
Structure + Function
Iris
- anterior end of the choroid
- consists of two involuntary muscles: circular and radial muscles which control the size of the pupil, controls the amount of light that enter the eye
Structure + Function
Pupil
- hole in the centre of iris that allows light to enter the eye
Structure + Function
Lens
focuses light rays onto retina by changing shape
Structure + Function
Suspensory Ligaments
holds the lens in position by attaching the lens to the ciliary body
Structure + Function
Ciliary Body
- supports the lens
- contains muscles which control the curvature of the lens
Structure + Function
Vitreous Humour
- supports the lens
- refracts light rays and keeps the eyeball firm
Structure + Function
Aqueous Humour
- refracts light and keep the eyeball firm
- maintains the shape of the anterior chamber of the eyeball
Areas of the Retina
Fovea
- images are normally focused here
- only contains cones which are densely packed
- part of retina that is the most sensitive to light
- provides acute colour vision in bright light when images are focused onto it
Areas of the Retina
Blind Spot
- found immediately over the optic nerve when it enters the eye
- no photoreceptor cells present (no vision)
Parts of the Retina
Other Areas
density of rods much higher than cones (rods provide vision in dim light)
Rods vs Cones
Rods
- dispersed in the periphery of the retina
- highly sensitive to low light level
- blurry, only shades of grey
Rods vs Cones
Cones
- concentrated in the fovea
- sensitive to high light intensity
- acute (sharp) and coloured images
Responses of the Eye
Human Visual System
- Reflected light rays from an object
