structure and functions of eye pdf

Structure And Functions Of Eye Pdf

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Parts of the Eye. Here I will briefly describe various parts of the eye:. The sclera is the white of the eye.

Eye anatomy and function

Human eye , in humans, specialized sense organ capable of receiving visual images, which are then carried to the brain. The eye is protected from mechanical injury by being enclosed in a socket, or orbit, which is made up of portions of several of the bones of the skull to form a four-sided pyramid, the apex of which points back into the head. Thus, the floor of the orbit is made up of parts of the maxilla, zygomatic, and palatine bones, while the roof is made up of the orbital plate of the frontal bone and, behind this, by the lesser wing of the sphenoid. The optic foramen , the opening through which the optic nerve runs back into the brain and the large ophthalmic artery enters the orbit, is at the nasal side of the apex; the superior orbital fissure is a larger hole through which pass large veins and nerves. These nerves may carry nonvisual sensory messages—e. There are other fissures and canals transmitting nerves and blood vessels. The eyeball and its functional muscles are surrounded by a layer of orbital fat that acts much like a cushion, permitting a smooth rotation of the eyeball about a virtually fixed point, the centre of rotation.

Human Eye: Anatomy, parts and structure

Members of the animal kingdom use different strategies to detect light and focus it to form images. Human eyes are "camera-type eyes," which means they work like camera lenses focusing light onto film. The cornea and lens of the eye are analogous to the camera lens, while the retina of the eye is like the film. To understand how the eye sees, it helps to know the eye structures and functions:. The coating on the interior back of the eye is called the retina.

Jump to content. The five senses include sight, sound, taste, hearing and touch. Sight, like the other senses is closely related to other parts of our anatomy. The eye is connected to the brain and dependent upon the brain to interpret what we see. How we see depends upon the transfer of light.

The structures and functions of the eyes are complex. Each eye constantly adjusts the amount of light it lets in, focuses on objects near and far, and produces continuous images that are instantly transmitted to the brain. The orbit is the bony cavity that contains the eyeball, muscles, nerves, and blood vessels, as well as the structures that produce and drain tears. Each orbit is a pear-shaped structure that is formed by several bones. The outer covering of the eyeball consists of a relatively tough, white layer called the sclera or white of the eye. Near the front of the eye, in the area protected by the eyelids, the sclera is covered by a thin, transparent membrane conjunctiva , which runs to the edge of the cornea.

Human Eye: Anatomy, parts and structure

Eyes are organs of the visual system. They provide animals with vision , the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons.

Special cells called cones and rods are located in the retina. These cells are known as photoreceptors and help absorb light. The majority of the cones are located in the macula, or central area, of the retina. Cone cells help us see colour and detail. Similarly, the macula allows us to read and clearly recognize people's facial details, such as eye colour and whether they have freckles.

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Казалось, что с той минуты, когда рано утром ему позвонил Стратмор, прошла целая вечность. Сдвинув в сторону пустые пивные бутылки, Беккер устало опустил голову на руки. Мне нужно передохнуть хотя бы несколько минут, - подумал. В нескольких милях от этого места человек в очках в железной оправе сидел на заднем сиденье фиата, мчавшегося по проселочной дороге. - Клуб Колдун, - повторил он, напомнив таксисту место назначения.

Все вокруг недоуменно переглянулись. Соши лихорадочно прогоняла текст на мониторе в обратном направлений и наконец нашла то, что искала. - Да. Здесь говорится о другом изотопе урана. Мидж изумленно всплеснула руками. - И там и там уран, но разный.

 - Джабба слушает. - Джабба, это Мидж. Он просиял. - Второй раз за один вечер. Что подумают люди.

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Он что-то скрывает. Джабба вытаращил глаза: - Мидж, дорогая. Я по уши опутан кабелем. Если ты хочешь назначить мне свидание, я освобожусь. Если же нет, то позвони электрикам.

Сьюзан отвечала на те вопросы, на которые могла ответить, и постепенно у Дэвида сложилось общее представление об Агентстве национальной безопасности - за исключением, разумеется, секретных сторон деятельности этого учреждения. Основанное президентом Трумэном в 12 часов 01 минуту 4 ноября 1952 года, АНБ на протяжении почти пятидесяти лет оставалось самым засекреченным разведывательным ведомством во всем мире.

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3 Comments

  1. Valdo S.

    Human eye , in humans, specialized sense organ capable of receiving visual images, which are then carried to the brain.

    30.04.2021 at 18:21 Reply
  2. Nipolscheban

    In humans and most mammals and birds, the iris plural: irides or irises is a thin, annular structure in the eye , responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina.

    04.05.2021 at 08:28 Reply
  3. Dandskiptira

    Pillars of eternity strategy guide pdf entrepreneurship and business management n4 pdf

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