The Five Major Senses PDF

The five major senses are taste, touch, smell, sight, and hearing. The accessory structures of the eye are the eyebrows, eyelids, eyelashes, and the lacrimal apparatus. The three tunics of the eye are the fibrous tunic (sclera), the vascular tunic (choroid), and the retina. The two chambers of...

The five major senses are taste, touch, smell, sight, and hearing. The accessory structures of the eye are the eyebrows, eyelids, eyelashes, and the lacrimal apparatus. The three tunics of the eye are the fibrous tunic (sclera), the vascular tunic (choroid), and the retina. The two chambers of the eye are the anterior chamber, which contains aqueous humor, and the posterior chamber, which contains vitreous humor. Image formation at the retina requires four basic processes: refraction, accommodation, constriction, and convergence. The photoreceptors of the retina are the rods and cones. The rods control vision in dim light, and the cones control vision in bright light. The cones are also responsible for color vision. Light entering the eye must travel through the cornea, the aqueous humor, the pupil, the crystalline lens, the vitreous humor, and finally the retina. The ear is divided into external, middle, and inner ears. The external ear flap is called the pinna (auricle); it extends into the external ear canal. The middle ear contains the ossicles and the entrance of the eustachian tube and ends with the tympanic membrane. The inner ear contains the vestibule, the cochlea, and the semicircular canals. The organ of Corti is the organ of hearing; it is located within the cochlea. The semicircular canals are responsible for the sense of balance and equilibrium. The taste buds differentiate four basic tastes: sweet, sour, salty, bitter, and umami (savory). Normal aging causes decreased hearing and sight as a result of normal changes of the structures. Individuals who have chronic disease or are older than 40 should be examined yearly to detect eye abnormalities or to prescribe changes in therapy. Refractory errors include hyperopia, presbyopia, and astigmatism. Ranges of 20/20 to 20/40 vision are considered normal, whereas 20/200 with correction is defined as legal blindness. ARMD is divided into two classic forms: dry and wet. In dry ARMD, which accounts for 90% of patients with ARMD, the macular cells have wasted or atrophied. Wet ARMD is characterized by the development of abnormal blood vessels in or near the macula. Cataracts are opaque areas in the lens and may be removed by intracapsular or extracapsular extraction. Glaucoma is not one disease but rather a group of disorders characterized by (1) increased IOP and the consequences of elevated pressure, (2) optic nerve atrophy, and (3) peripheral visual field loss. Loss of hearing may result from cerumen buildup, infection, trauma, or use of ototoxic drugs, or it may be a congenital condition. Conductive hearing loss is a decrease in amplification, whereas sensorineural hearing loss is interference within the inner ear and nerve conduction. Prevention of serious complications of ear disorders, such as infections, mastoiditis, and brain abscess, requires early detection and treatment. Potential for Injury is the primary patient problem for the patient experiencing vertigo, which occurs in labyrinthitis and Ménière’s disease. An essential communication tip for speaking to the hearing impaired is to face the patient and to speak clearly without shouting. A cochlear implant is a hearing device for the profoundly deaf. The implanted device is intended for the patient with sensorineural hearing loss.