Organs of special sense-
The special sense of hearing, sight, smell, and taste all have a special type of sensory receptors (nerve ending) outside. The brain sends the message to ears, eyes of balance. In the brain, incoming nerve impulses undergo a complex processor of integration and coordination results in a percolator of sensory information and a variety of responses inside and outside of the body.
THE EYE-
The eye is an organ sense of sight. The eyeball is almost of spherical shape and is situated in the interior part of the cavity. The eyeball contains three coats.
LIGHT TRANSMITTED STRUCTURES. THE THREE COATS OF EYEBALL.
1.Outer fibrous coat containing sclera and cornea.
2.Middle vascular coat containing choroid ciliary body and iris.
3.Inner nervous coat containing retina.
The light transmitted structures of-
(a)-Aqueous humor.
(b)-lens.
(c)-Vitreous humor.
1. Sclera-It forms the posteriors five-sixths of the outer coat. It forms the white of the eye and it 5 continuous with the cornea in the front sclera protect the internal structure and also maintain the shape of the eyeball. The optic nerve passes through the posterior aspect of the sclera and reaches the retina.
2. CORNEA- It forms the anterior or sixth of the outer coat. It has no blood supply but it's richly supplied by sensory nerves.
MIDDLE VASCULAR COAT-
1.CHAROID-It is them pigmented and highly vascular membrane. It lines the posterior compartment of the eye lying between the inner surface of the sclera and retina.
2. CILIARY BODY- It is the interior combination of the choroid and it is between choroid and iris. The ciliary body contains ciliary muscles. The suspensory ligament of the lens is attached to the ciliary muscles.
3.IRIS- It is an anterior continuation of the ciliary body is a pigmented membrane and the color of the eye is dependent ion on its pigment.Iris has a central opening called the pupil. Two sets of iris muscles control the pupil they are-
(a). Circular muscles reduce the pupillary size.
(b). Radical muscles increase the pupillary size.
3.INNER NERVE COAT-
Retina -It is the innermost nerves coat of the eyeball and lies immediately deeper into the choroid. The retina contains-
(a)- nerve cell and nerve fibers are in the inner surface (Facing chamber of the eye).
(b)-Some special structures called rods and cones which are on an outer surface of the retina they receive light and sets up impulses transmitted through the optic nerve.
(C)Optic dice is a point where the optic nerve leaves the eyewall.
(d)Macula is a small area of the retina situated entrance of the optic nerve.
