The Eye(Complete) Flashcards
What are the general features of the eye?
It is 2.5cm in diameter and is protected by the orbital( bony depressions) in the skull.
6 muscles control the movement of each eye.
There are 120 million light receptors in each eye( rods and cones) and they convert light into nerve impulses which are sent to the cerebrum of the brain to form a visual image.
What is the structure of the sclera?
The white part of the eye.
It is the outermost layer of the eye and is opaque.
It forms the cornea at the front of the eye.
What are the functions of the sclera?
To protect and give shape to the eyeball.
What is the structure of the choroid?
The dark and black middle layer with melanin.
What are the functions of the choroid?
To prevent internal reflection by absorbing any light rays that pass beyond the retina.
What is the structure of the retina?
The innermost layer of the eye.
Has rods and cones- photoreceptors.
What are the functions of the retina?
Converts light into nerve impulses so an image can form on the retina- generates impulses.
What is the structure of the fovea?
Part of the retina with cones only.
What are the functions of the fovea?
Provides detailed coloured vision in bright light.
What is the structure of the photoreceptors?
Sensory cells sensitive to light.
Contains rods and cones.
Contains the pigment rhodopsin which needs vitamin A.
What are the functions of the photoreceptors?
Rods:
Provide vision in dim light but only in black and grey.
Cones:
Provide detailed coloured vision in bright light.
What is the structure of the cornea?
Transparent front of eye with a curved surface to focus light.
What are the functions of the cornea?
To allow light to enter the light and bends it towards the retina.
What is the structure of the aqueous humour?
A clear liquid with salt.
What are the functions of the aqueous humour?
Contains the nutrients and oxygen for the cornea.
Maintains shape of cornea.
What is the structure of the vitreous humour?
Clear gel-like.