- SCLEROTIC LAYER
The transparent bulging, circular part of
sclerotic layer which lies in the front is called
Cornea is covered by the thin conjunctiva.
- CHOROID LAYER
Choroid layer starts from iris which is next to
cornea. It controls the amount of light
entering intothe eye.
The circular aperture of iris is called pupil.
Next is lens (proteinous). It is biconvex in nature.
Space between lens and cornea is filled with a transparent watery fluid called Aqueous Humour.
The space behind the lens is filled with Vitreous Humour.
Image of the object is formed on retina.
Rod cells: Sensitive to dim light
Cone cells: Color sensitive for 3 primary colors (Red, Blud and Green)
Yellow spot (Macula Lutea): On retina, finest image is formed here.
Blind spot: No image formation takes place here as the optic nerves innervate the eyeball here. Also the rods and cones are absent here.
Color of eye is the color of the iris.
Cornea is donated in eye donation
Eyes glow in animals due to tapetum.
DEFECTS OF EYE
Myopia: Cannot see distant objects, image formed before retina, concave lens is used.
Hypermetropia: Cannot see near objects, image formed behind retina, convex lens is used.
Astigmatism: Curvature of cornea becomes irregular and image is not clear. Cylindrical lens is used.
Cataract: Due to defective protein metabolism the lens becomes opaque.
Gloucoma: Due to defect in aqueous humour.
Xerophthalmia: It is due to deficiency of Vitamin A.
Presbiopia: In this, power of accommodation of lens decreases due to age factor and defected metabolism. Can be removed by bifocal lens.
It encloses 3 ear ossicles.
Middle ear is connected to the pharynx by Eustachian tube.
Various parts are there which perform 2 acts: Maintenance of balance and hearing.
Succulus and cochlea parts are associated with hearing. It is filled with a flud, perilymph.
In the internal ear are 3 semi-circular canals and utriculus which are filled with a fluid, endolymph. They perform the balancing act.