The Eye Flashcards
What is the function of the iris?
The iris is the colored part of the eye that controls the size of the pupil. It regulates the amount of light that enters the eye by contracting or dilating in response to varying light levels.
What is the function of the cornea?
The cornea is the transparent, dome shaped surface that covers the front of the eye. It helps to focus light as it enters the eye and provides a protective barrier against dirt, germs, and other particles.
What is the function of the pupil?
The pupil is the opening in the center of the iris that allows light to enter the eye. Its size adjusts to control the amount of light that reaches the retina, becoming larger in dim light and smaller in bright light.
What is the function of the lens?
The lens is a flexible, transparent structure located behind the iris that focuses light onto the retina. It changes shape to allow for clear vision at various distances, a process known as accommodation.
What is the function of the ciliary muscles?
The ciliary muscles are a ring of smooth muscle fibers that control the shape of the lens. When the ciliary muscles contract, the lens becomes thicker for near vision; when they relax, the lens becomes thinner for distance vision.
What is the function of the radial muscles?
The radial muscles are part of the iris and help to dilate the pupil in low light conditions. When these muscles contract, they pull the edges of the iris outward, allowing more light to enter the eye.
What are suspensory ligaments?
Suspensory ligaments, also known as zonules, are thin fibers that connect the ciliary muscles to the lens. They help hold the lens in place while allowing it to change shape during the process of accommodation.
What is the function of the sclera?
The sclera is the tough, white outer layer of the eye that provides structure, protection, and support to the eye. It also serves as an attachment point for the eye muscles.
What is the function of the choroid?
The choroid is a layer of blood vessels located between the sclera and the retina. It provides nutrients and oxygen to the eye and absorbs excess light to prevent scattering, which helps improve visual clarity.
What is the fovea?
The fovea is a small depression in the retina that contains a high concentration of cone photoreceptor cells. It is responsible for sharp central vision and is crucial for activities requiring detailed vision, such as reading.
What is the blind spot?
The blind spot is the area on the retina where the optic nerve exits the eye. This area lacks photoreceptors, meaning no visual information is detected here, resulting in a ‘blind’ spot in the visual field.
How does the eye adapt to dim and bright light?
In dim light conditions, the radial muscles contract to dilate the pupil, allowing more light to enter the eye. In bright light conditions, the circular muscles of the iris contract to constrict the pupil, reducing the amount of light that enters the eye.
What is eye accommodation?
Eye accommodation is the process by which the lens changes shape to focus on objects at different distances. For distant objects, the ciliary muscles relax, causing the lens to become thinner. For close objects, the ciliary muscles contract, making the lens thicker.
How does the lens change shape during accommodation?
When the ciliary muscles contract, the tension on the suspensory ligaments decreases, allowing the lens to become thicker and more curved, which increases its refractive power. Conversely, when the ciliary muscles relax, the tension on the suspensory ligaments increases, making the lens thinner and less curved.
What are the liquids in the cornea and the gel in the eyeball?
The cornea is maintained by a thin layer of aqueous humor, which provides nutrients and maintains intraocular pressure. The gel like substance in the eyeball is called vitreous humor, which fills the space between the lens and the retina.
