The eye Flashcards
What is the structure and function of the cornea?
Transparent outer covering of the eye that refracts light entering the eye.
What is the structure and function of the iris?
Pigmented ring of circular and radial muscles; controls the size of the pupil to regulate light entry.
What is the pupil?
A hole in the center of the iris that allows light rays to enter the eye.
What is the structure and function of the lens?
Transparent, bi-convex structure attached by suspensory ligaments to the ciliary muscle; refracts light to focus it on the retina.
What is the function of the ciliary muscles and suspensory ligaments?
Change the shape of the lens (accommodation) to focus light onto the retina.
What is the structure and function of the retina?
Light-sensitive layer composed of rod and cone cells; converts light into neural signals sent to the brain via the optic nerve.
What is the function of the optic nerve?
Transmits nerve impulses from the retina to the brain.
What are cone cells?
Cells in the retina that detect colour and are sensitive to bright light (high light intensity).
What are rod cells?
Cells in the retina that detect light in dim conditions (low light intensity).
What is accommodation?
The process where the lens changes shape (via ciliary muscles and suspensory ligaments) to focus light from near or distant objects onto the retina.
How does the eye focus on distant objects?
Ciliary muscles relax, suspensory ligaments tighten, lens becomes less convex, light is refracted less, and focused on the retina.
How does the eye focus on near objects?
Ciliary muscles contract, suspensory ligaments slacken, lens becomes more convex, light is refracted more, and focused on the retina.
What is long-sightedness?
Can see distant objects clearly but cannot focus on near objects.
Why is the iris reflex important?
It prevents bright light from damaging the retina.
How does bright light affect the pupil?
Light receptors detect it, circular muscles contract, radial muscles relax, the pupil contracts, and less light enters the eye.
How does dim light affect the pupil?
Light receptors detect it, circular muscles relax, radial muscles contract, the pupil dilates, and more light enters the eye.
