parts of the eye Flashcards
What is the ciliary body?
A thickened region at the front end of the choroid containing ciliary muscles that control the curvature or thickness of the lens.
What are the two functions of the choroid?
- Pigmented black to prevent internal reflection of light.
- Contains blood vessels that bring oxygen and nutrients to the eyeball and remove metabolic waste products.
What is the function of the suspensory ligament?
A connective tissue that attaches the edge of the lens to the ciliary body.
What is the cornea?
A dome-shaped transparent layer continuous with the sclera that refracts or bends light rays into the eye.
What is the aqueous chamber?
The space between the lens and the cornea filled with aqueous humour, which keeps the front of the eyeball firm and helps to refract light into the pupil.
What is the lens?
A transparent, circular, and biconvex structure that is elastic and changes its shape or thickness to focus light onto the retina.
What is the blind spot?
The region where the optic nerve leaves the eye, which does not contain rods or cones and is not sensitive to light.
What is the function of the optic nerve?
Transmits nerve impulses to the brain when the photoreceptors in the retina are stimulated.
What are photoreceptors?
Cells in the retina that consist of rods and cones, connected to the nerve endings from the optic nerve.
What do rods enable us to see?
They allow us to see in dim light and only in black and white.
What is the fovea?
A small yellow depression in the retina situated directly behind the lens, containing the greatest concentration of cones and enabling detailed colour vision in bright light.
Fill in the blank: The vitreous chamber is the space behind the lens filled with _______.
vitreous humour
What is the function of vitreous humour?
Keeps the eyeball firm and helps to refract light onto the retina.
True or False: Cones work well in dim light.
False
What is the function of the sclera?
The sclera is the white outer covering of the eyeball that protects it from mechanical damage
The sclera is continuous with the cornea, which is a dome-shaped transparent layer at the front of the eye.
What is the conjunctiva?
A thin transparent membrane covering the sclera in front that secretes mucus to keep the eyeball moist
The conjunctiva is a mucous membrane.
What do eyelashes do?
Help to shield the eye from dust particles
Where is the tear gland located?
At the corner of the upper eyelid
What are the functions of the tears secreted by the tear gland?
They wash away dust particles, keep the cornea moist, and lubricate the conjunctiva
This lubrication helps to reduce friction when the eyelids move.
What is the role of the eyelids?
Protect the cornea from mechanical damage and regulate light entry through squinting
What happens when the eyelids squint?
They are partly closed to prevent too much light from entering the eye and damaging the retina
What is the iris?
A circular sheet of muscles that controls the size of the pupil and the amount of light entering the eye
The iris contains a pigment that gives the eye its colour.
What is the pupil?
A hole in the centre of the iris that allows light to enter the eye
Fill in the blank: The _______ is a dome-shaped transparent layer at the front of the eye.
cornea
