Human Diseases and Conditions Chapter 5

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Chapter 5, Diseases and Disorders fo the Eye and Ear

Functional Process of the Eye

1) the images are formed on the retina; 2) the rods and cones are stimulated; and 3) nerve impulses are conducted to the brain

Parts of the Eye

Eyeball, Sclera, cornea, choroid, ciliary body, iris, retina

Eyeball

similar in shape to a sphere and is composed of a wall of primary structures in three concentric layers - the sclera, the choroid, and the retina - and is connected to the brain by way of optic nerve.

Sclera

the outermost layer, consists of though fibrous connective tissue that is visible as the white of the eye. Attached to the sclera are the six extrinsic muscles that move the eye.

Cornea

the colorless transparent structure on the front of the eye is continuous with the sclera on the anterior aspect of the globe. This transparent structure uses its curvature to help focus the light rays as they enter the eye.

Choroid

the middle layer of tissue. This layer is continuous with the Ciliary body and the iris. These vascular structures supply the tissue of the eye with oxygen and nutrients. Anteriorly, the choroid joins the Ciliary body, which contains Ciliary muscles used to focus the lens of the eye.

Ciliary body

secretes aqueous humor, the fluid found in the anterior portion of the eye. The Ciliary body is connected by suspensory ligaments to the biconvex, transparent lens of the eye. Also attached to the iris.

Iris

: attached to the Ciliary body and is the colored portion of the eye, which helps regulate the amount of light entering the eye. In a brightly lit environment the eyes contracts, causing the opening in the center of the iris, the pupil, to become smaller.

Retina

in the innermost layer of the eye, covering the posterior three quarters of the eye, It is a light-sensitive layer made up of photo-receptive cells called rods and cones.

Rods

function best in dim light, thereby enabling night vision

Cones

function in bright light and also detect color and fine detail

conjunctiva

covering the anterior externally visible portion of the sclera is a thin transparent membrane this is the conjunctiva. It begins at the edge of the cornea, extends over the exposed sclera, and folds Anteriorly to the line the inside portion of the lids.

Anterior Chambers

the space between the iris, and the anterior clear cornea

Maintenance of Pressure withing the Eye

is maintained by aqueous humor, which ultimately enters the general circulation of the body.

Aqueous Humor

the clear watery substance occupying the anterior chamber.

Vitreous Humor

the jellylike fluid, which filled the large cavity behind the lens, which is the vitreous body.

Internal Lens of the Eye

is elastic and therefore can focus images whether viewed close by or at a distance.

Key to Sight

light rays are the key to sight. The light rays enter the eye and pass though the cornea, aqueous humor, lens and finally the vitreous humor.

Extrinsic Muscle

there are six extrinsic muscles that control the movements of the eye; the muscles pull on the eyeballs, making the two move together to converge on one visual field.

Signs and Symptoms of Eye Disorders

Redness of the eye and Drainage from the eyes

Redness of the Eye

Pain, itching or burning in or around the eye; Swollen red eyelids

Drainage from the Eyes

Lesions/sores in or around the eyes; Visual disturbances; Unequal pupils, sudden loss of vision

Ophthalmologist

Doctor who specialized in the eye

Tests to identify Eye Disorders

Diagnostic tests for the eye diseases and conditions including the following: Eye charts, such as the Snellen chart to measure visual acuity; Tonomerty to measure intraocular pressure; Dilation to directly view the posterior structures of the eye, including the retina and optic nerve

Refractive Disorders

results in the eye being unable to focus light effectively on the retina

Hyperopia

Farsightedness

Myopia

Nearsightedness

Hyperopia

the eyeball is abnormally short as measured from front to back

Myopia

the eyeball is abnormally long as measured from front to back

Astigmatism

is an irregular focusing of the light rays entering the eye. It usually is cause by the cornea not being spherical

Presbyopia

: this condition is related to aging and usually starts in people in their mid-40's

Nystagmus

is an involuntary, repetitive, rhythmic movement of one or both eyes

Nystagmus

the eye movements can be horizontal, vertical, circular, or a combination of all of these.

Strabismus

a visual defect of misalignment is failure of the eyes to look at the same direction time, which primarily occurs because of weakness in the nerves stimulating the muscles that control the position of the eyes

Hordeolum

(Styes) are acute, focal inflammatory infections of the sebaceous glands of the eyelids

Keratitis

is an inflammation or infection of the cornea

Blepharitis

is inflammation of they margins of they eyelids involving hair follicles and glands.

Blepharitis

ulcerative form of blepharitis is usually the result of staphylococcal infection. Nonulcersitve blepharitis can be caused by allergies or exposure to smoke, dust or chemicals.

Hordeolum

often the result of staphylococcal infection and can be associated with and secondary to blepharitis.

Keratitis

is often caused by an infection resulting from the herpes simplex virus. Other forms of Keratitis can be caused by corneal trauma, or exposure of the cornea to dry air or intense light, as occurs during welding

Entropian

the eyelid margins (more often the margin of just the lower lid) turn inward, causing the lashes to rub the conjunctiva

Ectropion

a condition in which the lower eyelid everts from the eyeball and the exposed surface of the eyeball and the lining of the eyelid become dry and irritated.

Blepharoptosis

also called ptosis, is a permanent drooping of the upper eyelid, such that it partially or completely covers the eye.

Conjunctivitis

inflammation of the conjunctiva, the mucous membrane that covers the anterior portion of the eyeball and also lines the eyelids, is called conjunctivitis

Conjunctivitis

can be caused by infection, most commonly viral or bacterial, and also by irritation resulting from allergies or chemicals.

Cataract

a cataract is when the natural lens of the eye becomes opacified.

Cataract

usually develop slowly and gradually reduce visual acuity. The primary symptom is the deterioration of vision in the affected eye.

Cataract

caused by the aging process and may be congenital or may result form ocular trauma, drug toxicity or from systemic disease such as diabetes mellitus or a complication of other ocular disease.

Glaucoma

is damage to the optic nerve in the presence of elevated intraocular pressure. Glaucoma is one of the major caused of blindness. It is more common in patients older than 60 years of age.

Glaucoma

early treatment is essential: if not treated promptly the disease can lead to blindness because any vision lost as a result of the disease generally can not be regained.

Diabetic Retinopathy

a pathologic alteration of the retinal blood vessels and the pathologic proliferation of the retinal vessels.

Diabetic Retinopathy

is characterized by micro-aneurysm, hemorrhages, dilation of retinal veins, and the formation of abnormal new vessels (neovascularization). The condition usually occurs in both eyes, affecting the sharpness and clarity of vision. Diabetic retinopathy is a major cause of acquired blindness in the United States.

Diabetic Retinopathy

usually occurs about 8 to 10 years after the onset of diabetes mellitus.

Cancer of the Eye

may involve the globe (ocular tumors), the orbit (the bone surrounding the orbital cavity and the soft tissues and muscles that lie between the globe and the bone), the optic nerve, or the eyelids. Neoplasm may be benign, malignant, or metastatic from another location (secondary tumors)

Functioning Organs of Hearing

is to collect sound waves, or vibrations, from the air or environment and channel them to the tympanic membrane (eardrum), which begins to vibrate

Organ of hearing and balance

The ear and is composed of three sections: the outer, the middle and the inner ear.

The outer, the middle and the inner ear

Three Sections of the Ear

Outer Section Parts

the external ear, also called the pinna or auricle and the external auditory canal.

Outer Section Function

is to collect sound waves, or vibrations, from the air or environment and channel them to the tympanic membrane (eardrum), which begins to vibrate

Middle Section Parts

contains the tympanic membrane and three ossicles (tiny bones) called the malleus (hammer), the incus (anvil), and the stapes (stirrup). Also called Eustachian tube, which leads to a cavity (the pharynx) at the back of the nose. At the inner most region of the middle ear is the oval window

Middle Section Function

receives sound waves from the vibrating eardrum and relays them along the three bones to the oval window.

Inner Section Parts

contains two membrane-lined chambers, each filled with fluid, called the cochlea and the labyrinth.

Inner Section Function

the cochlea contains tiny hairs that change the sound waves in the fluid into nerve impulses, which then are transmitted to the brain via the auditory nerve. The Labyrinth is responsible for maintaining balance. It consists of three connected tubes bent into half circles, called the semicircular canals. Their function is to detect movement of the head and relay this information to the brain.

Common Signs and Symptoms of Ear Disorders

Hearing loss; Ear Pain or pressure; Tinnitus (ringing or buzzing noise); Vertigo (dizziness); Nausea and vomiting

Hearing Loss

two types: conductive loss and sensorineural loss

Conductive loss

is caused by an impairment of the eardrum or bones in the middle ear, which conduct sound waves to the cochlea in the inner ear.

Sensorineural loss

or nerve deafness, results form impairment of the cochlea or the auditory nerve.

Impacted Cerumen

an atypical accumulation of Cerumen in the canal of the outer ear. The wax accumulates and hardens and has a tendency to prevent sound waves form reaching the tympanic membrane (eardrum) resulting in decreased hearing.

Infective Otitis Externa

Inflammation of the external ear canal

Swimmer's Ear

inflammation and resulting infection of the outer ear canal after water has been entrapped during swimming is termed swimmer's ear.

Swimmer's Ear

sever pain; a red, swollen ear canal; hearing loss; fever; and pruritus are common symptoms of swimmer's ear.

Infective Otitis Externa

using an otoscope an examination an history of symptoms confirm the diagnosis.

Otoscope

a medical device which is used to look into the ears

Otitis Media

inflammation of the normally air filled middle ear with the accumulation of fluid behind the tympanic membrane.

Otitis Media

Is classified as either serious or suppurative, according to the composition of the accumulating fluid.

Suppurative

bacterial infection of the middle ear = the fluid is purulent (containing pus)

Serious

(nonsuppurative) viral infection = the fluid is clear and sterile

Otitis Media

An Otoscopy reveals the presence of a fluid-filled middle ear.

Otitis Media

Analgesics and decongestants may be ordered. Oral or topical antibiotics are ordered for cases of suppurative Otitis media. Surgical evacuation of the fluid (myringotomy)

Myringotomy

surgical evacuation of fluid

tympanopasty

tubes are inserted to prevent fluid build up.( involves actual grafting of tissue for an eardrum repairs.)

Meniere's Disease

a chronic disease of the inner ear that affects the labyrinth

Meniere's Disease

usually manifests in individuals between 40 and 50 years of age

Benign Paroxysmal Positional Vertigo

Benign paroxysmal positional vertigo is usually a vestibular system disorder. The patient complains of his/her head spinning, becoming worse with movement of the head. They also may complain of a feeling of their surrounds are moving.

Benign Paroxysmal Positional Vertigo

dizziness experienced is that the room is spinning while the body is still; this is a false sensation.

Labryhthitis

an inflammation or infection of the labyrinth of the inner ear.

Labryhthitis

Balance is affected, and nausea and vomiting may occur in some cases.

Labryhthitis

is usually the result of a virus but can be caused by a bacterial infection that has spread from the middle ear. It also maybe a result of meningitis.

Ruptured Tympanic Membrane

Any type of tear or injury to the eardrum. May be a result of pressure, force or insult from the exterior aspect or it may be cause by increased pressure within the middle ear.

Ruptured Tympanic Membrane

the four most common causes of a ruptured eardrum are insertion of sharp objects into the ear canal, a near by explosion (including lightning strikes), a severe middle ear infection and a blow to the ear. A ruptured eardrum also can occur as a result of a fractured skull.

Mastoiditis

whether acute or chronic, is inflammation of the mastoid bone, or mastoid process.

Mastoiditis

acute Mastoiditis is the result of neglected acute Otitis media. Streptococcus is the usual causative organism.

Sensorineural Hearing Loss

Sensorineural hear loss (deafness), also often referred to as occupational hearing loss, sound waves reach the inner ear but are not perceived because the nerve impulses are not transmitted to the brain.

Sensorineural Hearing Loss

The causes of Sensorineural hear loss is nerve failure or damage to the cochlea or eh auditory nerve. Also loud music, machinery noise, or sometimes the side effects of medications may be the cause.

Sensorineural Hearing Loss

hearing loss that is caused by damage to the cochlea is irreversible. Prevention is essential.

Cancer of the Ear

tumors of the ear can occur in any part of the ear and may be benign or malignant. Tumors may be primary or secondary.

Cerumen

ear wax

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