Pain

Pain, unpleasant sensory and emotional experience caused by real or potential injury or damage to the body or described in terms of such damage. Scientists believe that pain evolved in the animal kingdom as a valuable three-part warning system. First, it warns of injury. Second, pain protects against further injury by causing a reflexive withdrawal from the source of injury. Finally, pain leads to a period of reduced activity, enabling injuries to heal more efficiently.

Pain is difficult to measure in humans because it has an emotional, or psychological component as well as a physical component. Some people express extreme discomfort from relatively small injuries, while others show little or no pain even after suffering severe injury. Sometimes pain is present even though no injury is apparent at all, or pain lingers long after an injury appears to have healed.

Osteoporosis

Osteoporosis, bone condition characterized by a decrease in mass, resulting in bones that are more porous and more easily fractured than normal bones. Fractures of the wrist, spine, and hip are most common; however, all bones can be affected. White females are the most susceptible, but other risk factors include low calcium intake; inadequate physical activity; certain drugs, such as corticosteroids, and a family history of the disease.

The most common form of the disease, primary osteoporosis, includes postmenopausal (see Menopause), or estrogen-deficient, osteoporosis (Type I), which is observed in women whose ovaries have ceased to produce the hormone estrogen; age-related osteoporosis (Type II), which affects those over the age of 70; and idiopathic osteoporosis, a rare disorder of unknown cause that affects premenopausal women and men who are middle-aged or younger. Secondary osteoporosis may be caused by bone disuse as a result of paralysis or other conditions, including weightlessness in space; endocrine and nutritional disorders, including anorexia nervosa; specific disease processes; and certain drug therapies.

Prevention and treatment of osteoporosis include synthetic estrogen or progestin therapy or both for postmenopausal women, intake of calcium and other nutrients, weight-bearing exercise, and drugs such as calcitonin and alendronate sodium, a nonhormonal treatment for osteoporosis.

Osteomyelitis

Osteomyelitis, term applied to any inflammation of bone or bone marrow, usually caused by infection by such microorganisms as Staphylococcus aureus, various streptococci, Mycobacterium tuberculosis, and a host of others, as well as several fungi. The microorganisms generally reach the bone through the bloodstream from infection elsewhere. Occasionally osteomyelitis occurs by direct infection after surgery, after a compound fracture, or as a result of trauma.

Osteomyelitis, especially bacterial, may occur as an acute disease. Common symptoms include chills followed by fever, with acute pain and swelling above the site of inflammation. The inflammation begins in the marrow cavity and causes softening and erosion of the long bones, often with the formation of pus-containing abscesses, and soon spreads over the entire bone, with consequent death of the hard portions of the bone.

Chronic osteomyelitis, as is often seen in tuberculosis, fungus infections, or in patients with bacterial infections from other organisms, tends to run a slower and less dramatic course, with less severe pain and less fever, often resulting in bone destruction.

Acute osteomyelitis is treated by injections of antibiotics such as nafcillin, and by concurrent surgery to open the affected bone and drain the pus and dead tissue. Because of antibiotics, severe acute osteomyelitis is rare.

Obsessive-Compulsive Disorder

Obsessive-Compulsive Disorder, mental illness in which a person experiences recurrent, intrusive thoughts (obsessions) and feels compelled to perform certain behaviors (compulsions) again and again. Most people have experienced bizarre or inappropriate thoughts and have engaged in repetitive behaviors at times. However, people with obsessive-compulsive disorder find that their disturbing thoughts and behaviors consume large amounts of time, cause them anxiety and distress, and interfere with their ability to function at work and in social activities. Most people with this disorder recognize that their obsessions and compulsions are irrational but cannot suppress them.

Treatment for obsessive-compulsive disorder includes psychotherapy, psychoactive drugs, or both. Mental health professionals consider exposure and response prevention, a type of cognitive-behavioral therapy, to be the most effective form of psychotherapy for this disorder.

Medications to treat obsessive-compulsive disorder include selective serotonin reuptake inhibitors, such as fluoxetine (Prozac) and fluvoxamine (Luvox). A tricyclic antidepressant, clomipramine (Anafranil), also helps relieve symptoms of the disorder.

Obesity

Obesity, medical condition characterized by storage of excess body fat. The human body naturally stores fat tissue under the skin and around organs and joints. Fat is critical for good health because it is a source of energy when the body lacks the energy necessary to sustain life processes, and it provides insulation and protection for internal organs. But the accumulation of too much fat in the body is associated with a variety of health problems.

A calorie is the unit used to measure the energy value of food and the energy used by the body to maintain normal functions. When the calories from food intake equal the calories of energy the body uses, weight remains constant. But when a person consumes more calories than the body needs, the body stores those additional calories as fat, causing subsequent weight gain. Consuming about 3,500 calories more than what the body needs results in a weight gain of 0.45 kg (1 lb) of fat.

Obesity can become a chronic lifelong condition caused by overeating, physical inactivity, and even genetic makeup. No matter what the cause, however, obesity can be prevented or managed with a combination of diet, exercise, behavior modification, and in severe cases, weight-loss medications and surgery.