the human eye Flashcards
what are the features/functions of the iris?
the iris is a circular sheet of muscles which contain melatonin. a pair of circular and radial muscles control the amount of light entering the eye
what are the features/functions of the pupil?
it is a circular opening of the eye, that allows light to enter the eye
what are the features/functions of the sclera?
it is an outermost white tough fibrous coat that protects the eye. it progresses to form the transparent cornea in the eye
what are the features/functions of the lacrimal gland?
it secrets tears wnich wash dust away, keeps cornea moist and lubricages the conjuctiva
what are the features and functions of the conjunctiva?
it is a thin, transparent membrane covering the sclera, helping to lubricate the eye
what are the features/functions of the cornea?
it is a dome shaped, transparent refractive layer causing light rays to converge towards the pupil, causing the greatest refraction
what are the features/functions of the retina?
it is the innermost layer containing photoreceptors. nerve impulses generated are transmitted towards brain along sensory neurons in the optic nerve.
what are the features/functions of the fovea?
it contains the highest concentration of cones, with no rods
what are the features/functions of the choroid?
it is the middle layer, pigmented black to prevent TIR, contains blood vessels, and provides oxygen and glucose to retina and removes waste
what are the features/functions of the lens?
it refracts to focus light on the retina, due to the elastic and flexible nature of it. edge is attached to cillary body by suspensory ligaments. the curvature of the lens can be altered
what are the features/functions of the blind spot?
there are no photoreceptors where the optic nerve leaves the eye
what are the features/functions of the optic nerve?
it transmits nerve impulses from the retina to the brain, when photoreceptors are stimulated and from brain back to effectors for response
what are the features/functions of the cillary muscles?
they contract and relax to change the thickness of the lens
what are the features/functions of the suspensory ligament?
they attach the lens to the cillary body, and taut and slacken
what are the features/functions of the aqueous/virtuous humour?
they help to maintain the shape of the eyeball by providing an internal fluid pressure, and help to refract light
