(psychology Assignment) FUNCTIONS OF AN EYE.pptx

The anatomy of human eye under the light of psychology

1. NAME: RABIA FIAZ CLASS: BBA 4 ROLL NO. : 36 SUBJECT: PSYCHOLOGY TOPIC: FUNCTIONS OF EYE SUBMMITTED TO: MA’AM SADAF NAUSHAD <3

2. FUNCTIONS OF AN EYE

3. . The eye is a sensory organ. It collects light from the visible world around us and converts it into nerve impulses. The optic nerve transmits these signals to the brain, which forms an image so thereby providing sight. DEFINITION:-

4. . Human eyes primarily consist of two globe-shaped structures, the eyeballs, which are surrounded by the bony sockets of the skull, the orbits. The orbits are covered with fatty and fibrous tissue to protect the eye. Additional structures protecting the eye include the eyelids, the outer coating layer of the eye (fibrous tunic), the conjunctiva, and the lacrimal glands. Six special muscles that insert at different sites outside the eyeball work together to control eye movement. STRUCTURE:

5. The eyeball is surrounded by a three-layered wall, the three coats of the eye. They consist of different tissue and serve different functions. LAYERS OF THE EYE

6. 1. Outer Coat (fibrous tunic) The eye’s outer layer is made of dense connective tissue, which protects the eyeball and maintains its shape. It is also known as the fibrous tunic .

7. Sclera cornea The fibrous tunic is composed of the sclera and the cornea. The  sclera  covers nearly the entire surface of the eyeball. With its external surface being white- coloured , it is commonly known as the “white of the eye”. The sclera provides attachments for the muscles that control the eye’s movement The transparent  cornea  occupies the front center part of the external tunic. It serves as the eye’s “window”, which lets the light in and bends its rays, thereby providing most of the eye’s focusing power.

8. 2. Middle coat (vascular tunic) The middle layer of tissue surrounding the eye, also known as the vascular tunic or „ uvea “, is formed by The choroid, The ciliary body The iris.

9. A . Choroid: The  choroid  takes up the posterior five-sixths of the bulb and is mainly comprised of blood vessels. Its major functions are oxygen supply and nutrition for the eye. A dark pigment, melanin, occurs throughout the choroid in order to help limiting uncontrolled reflection within the eye, which would potentially result in the perception of confusing images .

10. B. Ciliary Body: The anterior part of the choroid passes into the  ciliary body , one function of which is anchoring the lens in place. The ciliary body contains a muscle ( ciliary muscle), which can change the shape of the lens for adjustment to far or near sight

11. C. Iris: The  iris , which is connected to the anterior part of the ciliary body, covers the top of the lens. Similar to the aperture of a camera, it controls how much light is let into the eye. The iris forms a circular, thin structure within the eyeball that regulates the size and the diameter of the pupil. It also contains pigments, the amount of which determines a person’s eye colour . For example, in children with blue eyes, the iris contains less pigment than in brown-eyed kids.

12. 3. Inner Coat: The third and inner coat of the eye is the retina, which is responsible for the perception of images – vision. The retina is a light-sensitive layer of nervous tissue composed of multiple sensory cells, so-called  light- or photoreceptor cells , as well as associated  nerve cells  and other types of cells, all working together to make a person see.

13. Photoreceptor Cells: For vision, there are two types of photoreceptor cells: rods and cones. Rods provide the perception of black-and-white vision, mostly in dim light, whereas cones help to see colors in daylight.

14. 4.The inner part of the eyeball The inner part of the eyeball consists of the: The Lens The vitreous body The two eye chambers.

15. A. The Lens: The lens is a transparent olive-shaped structure in the eye that has no blood vessels. Lens and cornea work together to focus the light rays passing through the eyeball to the back of the eye, that is, to the retina, by bending or refracting them, thereby creating clear images of the environment perceived from different distances. By adjusting its shape and size, the lens can change the focus. This process is called accommodation. Accommodation is possible thanks to the lens’ elastic capsule as well as to the lens fibers, which connect with the ciliary muscle

16. B. The Vitreous Body (vitreous humour , vitreous) The vitreous is a clear gelatinous mass held by collagen fibers. It is situated between lens and retina and comprises about two thirds of the entire eyeball. By pushing the retina towards the choroid, the vitreous promotes keeping the retina in place

17. C. The two eye chambers Anterior and posterior eye chamber. The anterior chamber of the eye is located between the iris and the cornea ( see above ). The posterior chamber is the space between parts of the iris and the lens. Both chambers are filled with aqueous fluid to nourish cornea and lens.

18. How the eye works: The human eye is a complex optical system that basically works like a camera: the iris serves as the aperture that controls the amount of light rays reaching cornea and lens (photographic objective), and the retina works as the film.

19. THE END