Chapter 8

The Musculoskeletal System

 Osteoporosis is a metabolic bone disease characterized by a

severe reduction in bone density; easy bone fracture.

occurs when the rate of bone resorption greatly exceeds the rate of bone formation.

Causes of OsteoporosisThe rate of bone formation decreases with age.

Osteomalacia and Rickets

O Osteomalacia is a metabolic bone disease seen in adults, caused by decreased mineralization of the bone as a result of a deficiency of calcium, phosphate, or both leading to soft, flexible bone.

O Usually, it results from a vitamin D deficiency or from renal disease.

O Rickets is a bone disease in children caused by vitamin D deficiency.

O Clinical Manifestations:O Osteomalacia may be symptomless until a fracture

occurs. Vertebral collapse is common, with associated changes in posture and height.

O Rickets is characterized by permanent skeletal deformity (bowed legs, lumbar lordosis, and rib and skull deformity)

O . Children may be unable to walk without support. They may also show poor dentition.

Diagnostic ToolsO - X ray.O - Measurements of serum calcium and phosphate

Chapter 9

The senses 

 Pathophysiologic Concepts

OAmblyopiaO The loss of visual acuity in an eye that appears

to be structurally intact, the central nervous system becomes unable to identify visual stimuli.

OStrabismusO Deviation in the position of the eyes relative to

each other. With strabismus, the eyes may appear to be crossed. An individual who has strabismus often complains of double vision.

ONystagmusO The involuntary, rhythmic movement of one or both

eyes is called nystagmus. The movement may be jerking, rotating, or pendular.

O MyopiaO Nearsightedness, occurs when the eye is unable to

accommodate sufficiently to objects that are far away.

O HyperopiaO Farsightedness; the eye is unable to accommodate

sufficiently to close objects O Hyperopia may be present early in life or may develop

later, typically after the fourth decade of life (presbyopia).

O AstigmatismO In astigmatism, light rays are scattered rather than focused on

the retina because of an asymmetric curvature of the cornea. O The image is distorted or blurred. O Astigmatism may occur with myopia or hyperopia.

O PapilledemaO Swelling of the optic disk where the optic nerve

leaves the eye and enters the brain. O It can occur in any condition that causes severely

increased intracranial pressure (brain tumor, infection, or injury)

O Papilledema is often an important diagnostic clue in severe brain pathology.

O Conductive Hearing LossO Decrease in hearing caused by a blockage in the

conduction of sound waves in the external or middle ear.

O It may occur if a foreign object is present in the ear or if there is an excessive wax or fluid buildup in the external or middle ear.

O Recurrent otitis media may cause conductive hearing loss. A hearing aid may offer improvement.

O Sensorineural Hearing LossO Sensorineural hearing loss is a decrease in

hearing caused by dysfunction of the organ of Corti, the auditory nerve, or the brain.

Conductive Hearing LossO Is a decrease in hearing caused by a

blockage in the conduction of sound waves in the external or middle ear.

OCauses:O a foreign object is present in the ear,

excessive wax or fluid buildup in the external or middle ear.

O Recurrent otitis media may cause conductive hearing loss. A hearing aid may offer improvement.

Sensorineural Hearing Loss

OSensorineural hearing loss is a decrease in hearing caused by dysfunction of the organ of Corti, the auditory nerve, or the brain.

OTinnitusODescribed as a ringing in one or both ears,

tinnitus may accompany ear wax buildup or presbycusis.

OAspirin overdose or other drugs may induce tinnitus. Middle-ear infection, or otosclerosis (irregular ossification of middle-ear bones) may also cause tinnitus.

Vertigo

O The sensation of motion or spinning, often described as a feeling of being off balance, is called vertigo.

O Vertigo is sometimes accompanied by nausea, weakness, and mental confusion.

O Inner-ear inflammation, especially of the semicircular canals, is the most common cause of vertigo

Conditions of Disease or Injury

OConjunctivitisO Inflammation of the conjunctiva of the

eye caused by an infectious process, physical irritation, or an allergic response is known as conjunctivitis. With inflammation, the conjunctiva becomes red, swollen, and tender. Conjunctivitis stemming from a bacterial infection is sometimes called pink eye.

OOtitisO Otitis is an inflammation of the ear.

Inflammation may be of the external ear canal, called otitis externa, or of the middle ear, called otitis media.