eyes Flashcards
(21 cards)
What membrane covers the outer surface of the eye?
The conjunctiva covers the outer surface of the eye. It is a clear thin membrane that lines the inside of the eyelids. This protects the eye and keeps it moist by producing a mucus layer that is part of the tears.
What gland releases tears?
The gland that releases tears is the lacrimal gland. It is located in the orbit above to the outside of the eye. The lacrimal gland continuously supplies tear fluid that’s wiped across the surface of your eye each time you blink your eyelids. The purpose is to lubricate, moisten and protect the surface of the eye.
What two things make up the fibrous layer of the eye?
The fibrous layer of the eye is made up of the Sclera (white part of the eye) and the Cornea (the transparent front part of the eye).
These two structures form the outermost layer of the eye, providing protection to the deeper structures and maintaining its shape. The sclera is the majority of the fibrous layer and provides a tough white outer covering for the eyeball. While the cornea is the transparent, dome-shaped front part of the eye that allows the light to enter.
Where are photoreceptors located?
The photoreceptors are located in the retina, at the back of the eye, specifically on the innermost layer of the retina adjacent to the retinal pigment epithelium.
The function of the photoreceptors is that the small cells that detect light and convert it into electrical signals that the brain can interpret as vision.
The two types of photoreceptors are called RODS and CONES.
Rods are primarily responsible for vision in low light conditions. (dark conditions)
Cones are responsible for color vision and detailed vision in bright light. (daytime vision)
What part of the retina lacks photoreceptors?
The part of the retina that lacks photoreceptors is the optic disc, or “blind spot” because it is where the optic nerve leaves the eye and contains no light-sensitive cells to detect images.
No photoreceptors (cells responsible for detecting light) = blind spot for vision.
What focuses light on the retina?
The lens of the eye is responsible for focusing light onto the retina and works together with the cornea. When light hits the retina (a light-sensitive layer of tissue at the back of the eye), special cells called photoreceptors turn the light into electrical signals.
What is the gelatinous part of the eye called?
The gelatinous part of the eye is called the vitreous. The vitreous is the gel-like fluid that fills your eye. It’s full of tiny fibers that attach to your retina (the light-sensitive layer of tissue at the back of the eye).
What is the reflexive movement of both eyes medially to view objects close to us called?
accommodation-convergence reflex.
What is the function of the choroid layer of the eye called?
The choroid supplies the outer retina with nutrients and maintains the temperature and volume of the eye.
What vision disorder results from loss of lens transparency?
cataract is a disease of the eye in which the normally clear lens has pacified, which obscures the passage of light. It is a gradually progressive disease and a significant cause of blindness around the world.
What part of the eye has the greatest visual acuity?
The fovea centralis, or fovea (responsible for central vision)
What layer of the eye contains rods and cones?
The layer of the eye that contains rods and cones is the retina.
The retina is the light-sensitive inner layer of the eye where the photoreceptor cells, known as rods and cones, are located.
What photoreceptor allows us to see gray tones?
Rods are the photoreceptor cells in the retina that allow us to see shades of gray in dim light.
Which area of the retina has the highest concentration of cones?
The fovea contains the most cones per square millimeter compared to any other area of the retina
What sex linked conditions affect more males for vision?
Red-green color blindness is a common trait that affects at least 10% of men and only one percent of women
What is another name for nearsightedness?
myopia. Myopia happens when the shape of the eye — or the shape of certain parts of the eye — causes light rays to bend or refract. Light rays that should be focused on nerve tissues at the back of the eye, called the retina, are focused in front of the retina instead
What is a photopupillary reflex?
The photopupillary reflex is the automatic response of the pupil to changes in light intensity. When bright light shines in the eye, the pupil constricts (gets smaller) to reduce the amount of light entering the eye. So in dim light the pupil dilates (gets larger) to allow more light to enter the eye. This reflex helps protect the retina from excessive light exposure and improves vision in lighting conditions.
What is the order of light when it passes through the eye?
From the cornea, the light passes through the pupil. The iris, or the colored part of your eye, controls the amount of light passing through. From there, it then hits the lens. This is the clear structure inside the eye that focuses light rays onto the retina.
What is the pathway of light through the eyeball and the process of light refraction?
Light first enters the eye through the cornea, where the cornea bends most of the light that enters the eye, helping it to focus toward the center of the eyeball. After that light travels through the aqueous humor. This fluid helps maintain intraocular pressure and provides nutrients to the cornea and lens. While it doesn’t refract light as much as the cornea, it helps to maintain the overall shape of the eye and aids in light transmission. Then light passes through the pupil and then the lens. The lens further refracts the light and focuses it onto the retina. Finally the light passes through the vitreous humor. The vitreous humor helps maintain the shape of the eyeball and allows light to travel without obstruction toward the retina.
Explain the difference between rods and cones?
Rods and cones are the two types of photoreceptor cells in the retina that are responsible for detecting light and transmitting visual information to the brain.Rods are responsible for vision in low-light conditions. They help you see in dim light and are crucial for night vision.Rods do not detect color but are sensitive to light intensity, allowing them to help detect shades of black, white, and gray in low-light situations. On the other hand Cones are responsible for vision in bright light conditions and allow you to see in full color.Cones are also responsible for sharp, detailed central vision.
Describe the role of the lens in vision. What is the disease caused by hardening of the lens?
The lens of the eye is a transparent, flexible structure located directly behind the pupil and iris. Its primary function is to focus light onto the retina, where the visual information is processed and sent to the brain via the optic nerve. The lens plays a key role in ensuring that images are sharp and clear, allowing us to see objects at various distances. However if your lens hardens as you age you can get the disease known as Presbyopia. This happens because the lens becomes less flexible, and it can no longer change shape to focus on close-up images. As a result, images appear out of focus.
