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The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens , the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power .
This dual function of the corneal endothelium is described by the "pump-leak hypothesis." Since the cornea is avascular, which renders it optimally transparent, the nutrition of the corneal epithelium, stromal keratocytes, and corneal endothelium must occur via diffusion of glucose and other solutes from the aqueous humor, across the corneal ...
A refractive cornea type eye of a human. The cornea is the clear domed part covering the anterior chamber of the eye. In the eyes of most mammals, birds, reptiles, and most other terrestrial vertebrates (along with spiders and some insect larvae) the vitreous fluid has a higher refractive index than the air. In general, the lens is not spherical.
The lens and the epithelium of the cornea arise from the surface ectoderm directly; other structures come from either the neural ectoderm or the neural crest, which itself arises from the ectoderm. The mesoderm has limited contributions: it is the origin of the vitreous body , the blood vessels of the eye, and the extraocular muscles.
Lastly, the cornea is a multifunctional tissue. It provides a large part of the eye's refractive power, meaning it has to maintain remarkable transparency, but must also serve as a barrier to keep pathogens from reaching the rest of the eye, similar to function of the dermis and epidermis in keeping underlying tissues protected.
Sampling of human stratum corneum using a tape-stripping method [1]. The stratum corneum (Latin for 'horned layer') is the outermost layer of the epidermis.Consisting of dead tissue, it protects underlying tissue from infection, dehydration, chemicals and mechanical stress.
The ciliary epithelium of the ciliary processes produces aqueous humor, which is responsible for providing oxygen, nutrients, and metabolic waste removal to the lens and the cornea, which do not have their own blood supply. Approximately 80% of aqueous humor production is carried out through active secretion mechanisms (the Na+K+ATPase enzyme ...
The cornea is composed of either one or two cuticular layers depending on how recently the animal has moulted. [32] Along with the lens and two humors, the cornea is responsible for converging light and aiding the focusing of it on the back of the retina.