How does the conjuctiva protects the cornea?

[PRINCESS NOOR]

i have certain questions related to the eye, which are need to be answer if possible:

1. how does the conjuctiva protects the cornea?
2. does the vitreous humour and the sclera have the same function?

(because i read in one book that the function of the vitreous humour is to maintain the shape of the eye,and i know the function of the sclera is to maintain the shape of the eye too).

3. does the lens consider as a living or non-living?why?

many thanx

 

[DocToxyn]

1. how does the conjuctiva protects the cornea?

The conjunctiva serves to secrete mucous to aid in lubrication and cleaning of the corneal surface.

2. does the vitreous humour and the sclera have the same function?

(because i read in one book that the function of the vitreous humour is to maintain the shape of the eye,and i know the function of the sclera is to maintain the shape of the eye too).

You're right that they both take part in the shaping of the eye, but for two different reasons. The sclera in the outer membrane of the eye thus serving to hold everything in. Much of that "everything" is vitreous humor, a viscous fluid that also supports the eye by being bounded by the sclera, if the vitreous humor was not there the sclera would be an empty bag, if the sclera was not there all you would have is a puddle. The vitreous humor may also take place in lens maintenance since a considerable amount of the antioxidant, vitamin C, is found in this tissue, which brings us to...

3. does the lens consider as a living or non-living?why?

The lens forms from the inside out and is made up primarily of cells containing crystallin proteins. These proteins, while in solution, allow the lens to function as an optically-clear, cell-based structure used to accommodate distance vision. These cells are no longer in contact with the circulatory system and thus have reduced metabolism to little or none, effectively making then non-living. The fascinating thing about these cells and their associated crystallin proteins is their extremely long lifespan. Most proteins live for at most hours or days, but these lens proteins must maintain solubility and optical clarity for the lifetime of the animal. This doesn't always happen and cataracts result which cloud the lens as these proteins breakdown and aggregate. That may be part of the function of the antioxidants found in the vitreous humor, to cut down on oxidative damage in the lens.

Check these websites for more eye/crystallin related material
http://webvision.med.utah.edu/
http://www.chemsoc.org/chembytes/ezine/2002/gross_jan02.htm

 

[ravenprp]

1. The conjunctiva is a thin, transparent layer of tissue that covers the front surface of the eye, including the cornea. It plays an important role in protecting the cornea by providing a barrier against foreign objects, bacteria, and other irritants from entering the eye. It also helps to lubricate the eye and keep it moist, which is essential for maintaining the health of the cornea. Additionally, the conjunctiva contains specialized cells that produce mucus, which helps to trap and remove any debris or particles that may come into contact with the cornea.

2. The vitreous humor and the sclera do not have the same function. The vitreous humor is a clear, gel-like substance that fills the space between the lens and the retina. Its main function is to provide support to the eyeball and maintain its shape. On the other hand, the sclera is the white, tough outer layer of the eye that helps to protect the delicate structures inside. It also provides attachment points for the muscles that control eye movement.

3. The lens is considered a non-living structure. It is made up of proteins and other molecules that do not have the ability to carry out metabolic processes or reproduce. However, it is a vital part of the eye and plays a crucial role in focusing light onto the retina, which allows us to see. Without the lens, our vision would be greatly affected.