Can someone give me help?

Question

Plz define these:sclera, cornea, choroid, iris, retina, optic disc, lens, pupil, optic nerve, retinal artery. I know its alot but I forgot my notes in my book. Its not Super serious, but better now than in the morning. thank you.

Please, no stupid answers like get a life, I'm just looking for help,not cheating.

Tank you to the people who give me real answers.

*thanks*sorry

Answer 1

CORNEA: the clear part of the eye covering the iris and pupil, it permits light to enter the eye

IRIS: a pigmented membrane that lies between the cornea and the lens, it acts as a diaphragm to widen or narrow the opening called the pupil.

LENS: the nearly spherical body in the eye, located behind the cornea, that focus light rays into the retina.

OPTIC NERVE: part of the eye that carries stimuli from the rods and cones to the brain.

OPTIC DISK: (AKA optic nerve head) circular area where the optic nerve enters the retina and location of the blind spot.

PUPIL: the round, dark center of the eye which opens and closes to regulate the amount of light the retina receives.

RETINA: The sensory membrane that lines the eye.

SCLERA: the outer coat of the eyeball that forms the visible white of the eye.

CLOROID: layers of blood vessels located between the sclera (white of the eye) a the retina. they provide.

RETINAL ARTERY: carries oxygen-rich blood to the retina.

Answer 2

1.Sclera

The sclera is the white of the eye. "Don't shoot until you see their scleras."

Exterior is smooth and white
Interior is brown and grooved
Extremely durable
Flexibility adds strength
Continuous with sheath of optic nerve
Tendons attached to it


2.The Cornea


The cornea is the clear bulging surface in front of the eye. It is the main refractive surface of the eye.

Primary refractive surface of the eye
Index of refraction: n = 1.37
Normally transparent and uniformly thick
Nearly avascular
Richly supplied with nerve fibers
Sensitive to foreign bodies, cold air, chemical irritation
Nutrition from aqueous humor and
Tears maintain oxygen exchange and water content
Tears prevent scattering and improve optical quality


3.Anterior & Posterior Chambers

The anterior chamber is between the cornea and the iris
The posterior chamber is between the iris and the lens
Contains the aqueous humor
Index of refraction: n = 1.33
Specific viscosity of the aqueous just over 1.0 (like water, hence the name)
Pressure of 15-18 mm of mercury maintains shape of eye and spacing of the elements
Aqueous humor generated from blood plasma
Renewal requires about an hour
Glaucoma is a result of the increased fluid pressure in the eye due to the reduction or blockage of aqueous from the anterior to posterior chambers.


4.Iris/Pupil

Iris is heavily pigmented
Sphincter muscle to constrict or dilate the pupil
Pupil is the hole through which light passes
Pupil diameter ranges from about 3-7 mm
Area of 7-38 square mm (factor of 5)
Eye color (brown, green, blue, etc.) dependent on amount and distribution of the pigment melanin

5.Lens

Transparent body enclosed in an elastic capsule
Made up of proteins and water
Consists of layers, like an onion, with firm nucleus, soft cortex
Gradient refractive index (1.38 - 1.40)
Young person can change shape of the lens via ciliary muscles
Contraction of muscle causes lens to bulge
At roughly age 50, the lens can no longer change shape
Becomes more yellow with age: Cataracts
The graph on the right shows the optical density (-log transmittance) of the lens as a function of wavelength. The curves show the change in density with age. More short wavelength light is blocked at increases ages.

6.Vitreous Humor

Fills the space between lens and retina
Transparent gelatinous body
Specific viscosity of 1.8 - 2.0 (jelly-like consistency)
Index of refraction, n=1.33
Nutrition from retinal vessels, ciliary body, aqueous
Floaters, shadows of sloughed off material/debris in the vitreous
Also maintains eye shape
Retina




The light has to pass through many layers of cells before finally reaching the photoreceptors. The photoreceptors are where the light is absorbed and and transformed into the electrochemical signals used by the nervous system. This change is called TRANSDUCTION.

The interior of the eyeball is the "inner" side and the exterior is the "outer" side. The nuclear layers contain cell bodies. The plexiform layers contain the connections between cells in the retina.




Again the light in entering from the bottom passing through all these layers before being absorbed in the receptors.

You can see the two types of receptors: the rod-shaped rods and the cone-shaped cones. The signal, after transduction, is passed to the horizontal cells (H) and the bipolar cells via a layer of connections. Lateral processing takes place in this layer via the horizontal cells. The throughput is transferred to another layer of connections with the amacrine cells (A) and the ganglion cells. The amacrine cells also exhibit lateral connections in this inner plexiform layer. The signals pass out of the eye via the ganglion cell axons which are bundled together to form the optic nerve.

The retina has a similar layered structure as the gray-matter top layers of the cerebral cortex of the brain. In fact, the retina is an extension of the central nervous system (the brain and spinal cord) that forms during embryonic development. This is one reason why scientists are interested in retinal processing; the retina is an accessible part of the brain that can be easily stimulated with light.


Speaking of the optic nerve...

The location where the optic nerve is bundled and leaves the retina is known as the optic disk. There are no photoreceptors at the location of the optic disk and hence there is a blind spot. The scientific term for a blind spot is a scotoma. So the blind spot due to the optic disk is a natural permanent scotoma in normal vision

Answer 3

i have most all of your words at the yahoo search by
http://www.stlukeseye.com here's how. go to yahoosearch and we want find what chloride is then press search after you type it. stroll down until you see 2. chloride- eye anatomy click and you will find all the words except optic disc and retinal artery so go to wikipedia and it gives you as long definition.
hope i helped
love desi

Answer 4

Stop being lazy and do your own work. You're sitting at the computer. The answers are just a click away.

Answer 5

Click on http://www.99main.com/~charlief/Blindness.htm
it has all the parts- I found it online by typing in parts of the eye. You should print it out, and be able to study it.

Answer 6

there all part of the eye go onto an anatomy website

Answer 7

Check out:

www.m-w.com (Merriam Webster online)
www.wikipedia.org

Answer 8

type in dictionary in Yahoo search.

Answer 9

parts of the eye?

Answer 10

Here you go sweety:

http://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_8/ch8p3.html