Parts of an Eye – Class 11 | Chapter – 21 | Biology Short Notes Series PDF

Parts of an Eye: The eye is an important and one of the most complex sensory organs that we humans are endowed with. It helps us in visualizing objects and also helps us in light perception, colour and depth perception. Besides, these sense organs are pretty much similar to cameras, and they help us see objects when light coming from outside enters them. That being said, it is quite interesting to understand the structure and working of the human eye. It also helps us in understanding how a camera actually functions

Parts of an Eye

Its directly located in a bony socket in the skull extending only a small portion outside which can be seen. Scientifically, the wall of the eye comprises of three layers namely: the outermost layer, the middle layer, and the innermost layer.

The outermost layer: It’s also known as the sclera which is a whitish tough layer with tissues connected together. The function of the sclera is mainly to protect and maintains the shape of the eyeball.

The middle layer: also called the choroid is made up of black pigmented cells with very rich supply of blood capillaries, this layers forms the ciliary body and the iris.

The innermost layers: this is the retina; it’s a light sensitive portion of the eye due to the fact that it has numerous photoreceptors which are of two types (rods and cones). The rods are responsible for black and white visions. It’s also helpful to see at night while the cones are responsible for various colour visions. The retina is directly located behind the eyeball. The capillary in the middle choroid supply the retina with available nourishments.

Eye Structure

Conjunctiva: the conjunctiva gland is the portion that contains mucus for moistening the eye; it helps to keep the eyes moist at all times. Failure or malfunctions of this gland might probably result to serious pains and itching. The conjunctiva protects the cornea too

Iris: in the iris, the colour of the eye is determined. It’s the segment that gives the eye it colour, it’s the iris that surrounds the pupils in all it sides. The iris widen and shrink the pupils depending on the intensity of light into the eye, if light is low; the iris will widen the pupil and vice versa.

Lens: this is a very transparent layer, after the pupils receives the light from it surrounding, the lens then focus the light unto the retina.

Pupil: it’s at the centre of the eye; it’s like a black dot with tiny hole that allows the passage of light.

Cornea: it’s a domed shaped structure that serves as a cover to the eye against anything which can cause harm to the eye.

Sclera: the sclera is regarded as the outermost part of the eye; it’s white in colour and maintains the shape of the eyeball.

Choroid: it’s the interphone between the retina and sclera which is responsible for the provision of nutrient to other part of the eye.

Retina: it can be found at the back of the eye, it major function is to receive light from the focus and transmit it to electrical impulse before being sent to the brain.

Macula: it’s standing very close to the retina, which helps the eyes to focus on an object.

Optic nerves: this is the collections of nerves that carry impulses from the retina to the brain.

Anterior and posterior chambers: in the eye interior section, the front part is the anterior chamber while the back part is the posterior chamber

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By Team Learning Mantras