Essay Example on The five senses humans Have

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The five senses humans have are sight smell touch taste and hearing The eyes and ears have sensitive receptors and are considered sense organs The main function of the eyes is to convert light into electrical impulses which can be sent to the brain The brain reads these signals as visual images The ears are divided into three parts outer middle and inner regions The function of the outer and middle part of the ear is to direct sound waves through the ear The inner ear receives the sound and has structures to send impulses to the brain When sound waves enter the ear they interact with receptor cells The nerve fibers within the ear lead to the cerebral cortex region of the brain and are interpreted as sounds The pupil is at the center of the eye and is where light rays enter The iris is the colored area of the eye The membrane that lines the eyelids and the white of the eye is called the conjunctiva It is a clear membrane unless the blood vessels are dilated The blood vessels can become dilated in a few ways including infection allergies or smoke Light entering the eye passes through the cornea a fibrous tissue over the pupil and iris The sclera is the white part of the eye and lies under the conjunctiva Located within the sclera is a brown membrane termed the choroid

The ciliary body is all around the eye and contains zonules which are thin attachments that connect it to the lens Muscles in the ciliary body allow the lens to change shape which causes refraction of light Refraction can be defined as the bending of light rays as they pass through the tissues of the eye Accommodation occurs when the eyes focus on an object from near or far This process decreases as people get older The area behind the lens is called the vitreous chamber It contains a soft material that gives the eye its shape If this area is damaged blindness may result The optic nerve is the part of the eye that sends impulses to the brain The macula is next to the optic disc and is oval in shape It contains the fovea centralis which is made of cones and is the area where the clearest vision occurs If the macula or fovea centralis is damaged blindness may result A cataract can be classified as a degenerative eye disease however it is possible to be born with cataracts For a cataract to form protein in the lens builds and clouds vision Other ways this disease can occur is from trauma diabetes mellitus and chronic corticosteroid usage Cataracts can easily be seen with an ophthalmoscope and with the human eye This can be fixed by removing the lens via surgery and replacing it with an artificial lens Glasses or contacts can also be worn to improve vision 



A chalazion is small cystic mass on the eyelid Prolonged inflammation of a sebaceous gland causes this disease Chalazions can be cut open and drained Diabetic retinopathy is a retinal effect of diabetes mellitus Fluid can leak from blood vessels into the retina causing vision to become blurred This is called macular edema If severe hemorrhaging on the retina has happened laser photocoagulation can be helpful Treatment involves injection of medication into the vitreous jelly Another method is to use corticosteroids to slow fluid leakage from the vessels A disease where damage to the retina and optic nerve from increased intraocular pressure is called glaucoma The increased pressure is from the failure of the aqueous humor to drain from the eye to the bloodstream This pressure is built up in the anterior chamber It is diagnosed by giving the patient an anesthetic and then using an instrument that is applied to the outside of the eye If glaucoma is not treated blindness can result This disease can cause dilation of the pupil redness blurred vision and pain Medication can be given to lower the pressure or laser therapy can be used to create an opening to allow aqueous humor to flow Hordeolum is an inflammatory infection in the eyelid A hot compress is often used to help drainage A surgical incision can also be done Macular degeneration causes loss of central vision However peripheral vision is maintained It can occur in two forms The wet form develops from leaky blood vessels adjacent to the macula and the dry form is from degeneration of retinal cells Dry macular degeneration occurs most often and there is no treatment although vitamin and mineral supplements help decrease the progression

The wet form can be treated with laser photocoagulation This disease is one of the most common causes of blindness in the elderly Nystagmus is a condition in which one or both eyes make uncontrolled and repetitive movements Brain tumors can be a cause Separation of the retina from underlying tissue within the eye is a disease called retinal detachment This can occur in several ways including trauma bleeding infection or tears in the retina This condition can cause flashes of light to be seen or photopsia Small tears can be treated by photocoagulation and cryotherapy More severe tears require a scleral buckle to be sutured to the sclera right over the separated portion Any misalignment of the eyes is termed strabismus A weak eye muscle does not allow the eyes to look in the same direction There are different forms depending on which way the eye deviates Esotropia is when the eye turns inward and exotropia is when the eye turns outward Hypertropia is an upward deviation and hypotropia is a downward deviation This condition may lead to diplopia in adults


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