Draw a neat labelled diagram of a Human eye. Discuss how the light rays are focused on the retina. Q.2 Name the parts of human eye:
(a) that maximum refracts the light entering into the eye.
(b) that controls the amount of light entering into the eye.
(c) that provides the fine adjustment to focus images of the objects
(d) that forms the real, inverted image of the object formed on it.
Q.3 When one enters a less lighted room from a place of intense light, he is not able to see anything for sometimes but after
sometimes the things become somewhat visible. Why?
Q.4 Name the muscles assisting the eye lens to provide the fine adjustment to focus images of the objects. Q.6 What is the function of Iris in the human eye.
Q.7 Name the two fluids present in the human eye.
Q.8 (a) Define ‘accommodation’ of a eye.
(b) Write the modification in the curvature of the eye lens which enables us to see the (i) nearby objects and (ii) far objects clearly without any strain.
Q.9 What are the limits of accommodation power of a healthy normal human eye? Q.10 What is cataract. How is the impaired vission due to cataract corrected ?
Answers
Answer:
Eyes are the paired sense organs located in the sockets of the skull which are called orbits. Eyes are supplied with the second cranial nerve called optic nerve.
The wall of eyeball consists of following three layers:
1. External layer: It is composed of a dense connective tissue called the sclera which maintains the shape of the eye and also protects it. The anterior portion of this layer is called cornea. Cornea absorbs oxygen from air and helps in focussing light waves as they enter the eye.
2. Middle layer: The middle layer is choroid which contains many blood vessels and it appears bluish in color. The choroid layer is thin over the posterior two-third of the eyeball and it becomes thick in the anterior portion to form the ciliary body. The ciliary body continues forward and forms a pigmented and opaque structure called the iris.
Eyeball possess a transparent crystalline lens held in place by the ligaments attached to the ciliary body. The aperture surrounded by iris, in front of the lens is called pupil.
3. Inner layer: This layer contains retina. The retina contains three layers of cells- ganglion cells, bipolar cells and photoreceptor cells. Photoreceptor cells are of two types- rods and cones that contain the light-sensitive proteins called the photopigments.
The optic nerve leaves the eye and retinal blood vessels enter it at a point medial to and slightly above the posterior pole of eyeball called blind spot because here, photoreceptors cells are absent.
A yello
Answer:
Study text book u might get answers. Mark me brainliest please ✌️✌️