Eyes Flashcards
Sclera
The white, opaque outer layer of the eye that provides protection and form.
Cornea
The transparent, dome-shaped front part of the eye that refracts light entering the eye.
Iris
The colored part of the eye containing muscles that control the size of the pupil.
Pupil
The black circular opening in the center of the iris that regulates the amount of light entering the eye.
Lens
A transparent, flexible structure behind the iris that focuses light onto the retina.
Retina
The light-sensitive inner layer of the eye that contains photoreceptor cells (rods and cones) and converts light into neural signals.
Optic Nerve
The nerve that transmits visual information from the retina to the brain.
Macula
A small central area in the retina responsible for detailed central vision.
Fovea Centralis
A tiny pit in the macula that provides the sharpest vision due to a high concentration of cones.
Choroid
The vascular layer between the sclera and the retina that supplies blood to the eye.
Ciliary Body
A ring of tissue behind the iris that produces aqueous humor and contains the ciliary muscle, which controls lens shape.
Aqueous Humor
The clear fluid in the anterior chamber of the eye that maintains intraocular pressure and nourishes the cornea and lens.
Vitreous Humor
The clear, gel-like substance filling the space between the lens and the retina, helping to maintain the eye’s shape.
Conjunctiva
The thin, transparent membrane covering the front of the eye and lining the inside of the eyelids, providing lubrication and protection.
Suspensory Ligaments (Zonules)
Fibers that connect the ciliary body to the lens, holding it in place and allowing it to change shape for focusing.7
Rods
Highly sensitive to low light levels, enabling vision in dim conditions (scotopic vision). They do not detect color and provide low spatial acuity.
Cones
Operate in bright light conditions (photopic vision) and are responsible for color vision.
What are the 3 cone types?
Cone L
Cone M
Cone S
There are three types of cones, each sensitive to different wavelengths corresponding to red, green, or blue light.
what is rhodopsin?
Rhodopsin is a light-sensitive receptor protein found in the rod cells of the retina. Enables vision under low-light conditions.
When happens when rhodopsin is inactive?
rhodopsin is inactive in darkness. photoreceptor cells remain depolarized due to open sodium channels, and glutamate is continuously released.
When happens when rhodopsin is active?
rhodopsin is active in the light. initiating a cascade that leads to the closure of sodium channels in the photoreceptor cell membrane. This results in hyperpolarization of the cell and a decrease in the release of the neurotransmitter glutamate.
Accommodation for near target
lens becomes thicker and more curved. This increased curvature enhances the lens’s refractive power, allowing it to bend light rays from close objects more effectively.
pupils constrict to reduce the amount of light entering the eye
Accommodation for far target
tension flattens the lens, reducing its curvature and decreasing its refractive power, which is optimal for focusing parallel light rays from distant objects onto the retina.
pupils may dilate slightly to allow more light into the eye
