Question

The given diagram shows different parts of the human eye with one part labelled as X. Which the following statement is correct regarding label X?

A) It is the opening in the lens that permits light into the inner chambers of the eye.
B) It is the coloured portion of the vascular tunic.
C) It is a biconcave structure that changes shape to bring objects into focus.
D) It is the thick, jelly-like substance in the posterior compartment of the eye.

Answer 1

Hint:
Muscles of the X are regulated by the autonomic nervous system. Parasympathetic nerve fibers innervate the circular muscles (causing papillary constriction) and sympathetic fibers supply the radial muscle (causing papillary dilation).

Complete answer:
The cornea is a transparent coat that covers the colored iris. Because it is curved, the cornea helps to focus light onto the retina. The iris is the pigmented and colored portion of the eye. The round opening in the center of the iris through which light enters the interior portions of the eye is the pupil. The iris contains circular muscles that constrict and radial muscles dilate the pupil. The pupil acts like the diaphragm of a camera, dilating and constricting the pupil to allow more or less light into the eye.

Option ‘B’ is correct

Note:
The vitreous chamber is in the posterior segment of the eye. The vitreous humour fills the vitreous chamber and it is a gelatinous mass. Uvea is the iris, ciliary body, and choroid collectively. Iris comes under a vascular tunic made up of the ciliary body, iris, and choroid.