eye Flashcards
cornea
refracts light
iris
controls how much light enters the pupil
lens
focuses light onto the retina
retina
contains light receptor cells some of wjocj are sensitive to light of different colours
optic nerve
carries electric impulses from the retina to the brain
how do eyes detect light?
the 👁 detects 💡
the 💡 sensitive cells that detect 💡 are located in the retina. they are the rods and cones
the rods and cones receive 💡 and convert the 💡 energy into an electrical impulse which is then sent through the optic nerve to the 🧠
how does the iris control the size of the 👩🏼🎓?
this is done by the antagonistic action of two types of muscles - circular and radial
bright light
the circular muscles contract to that the pupil becomes constricted, allowing less light into the eye so the risk of damage to the retina is reduced
dim light
the radial muscles contract to that the pupil becomes dilated, allowing as much light as possible into the eye
accommodation
this is the ability of the lens to alter its curvature in order to focus light from near or distant objects
focusing on a close object
light from a near objects enter the eyes in diverging rays
the lens has to refract the light a lot in order to focus the light rads onto the retina. thus the lens needs to be more convex
the ciliary muscles contract and slacken/loosen their hold on the suspensory ligaments so that the lens becomes more convex
focusing on a distant objecti
light from a distant object enters the lens in straight lines
the lens has to refract the light very little in order to focus the light rays onto the retina so a less convex lens is needed
the ciliary muscles relax, pulling the suspensory ligaments so that the lens is pulled into a less convex shape
