Factitious disorder: A disorder in which a person feigns or induces symptoms, typically for the purpose of assuming the role of a sick person.

Lymphocyte: White blood cell that circulates through the lymph system and bloodstream, helping the body identify and destroy antigens and cancer cells.

Immune system: The body’s network of activities and cells that identify and destroy antigens and cancer cells.

Type B personality style: A personality pattern in which a person is more relaxed, less aggressive, and less concerned about time.

Somatic symptom disorder: A disorder in which people become excessively distressed, concerned, and anxious about bodily symptoms that they are experiencing, and their lives are greatly and disproportionately disrupted by the symptoms.

Psychoneuroimmunology: The study of the connections among stress, the body’s immune system, and illness.

Behavioral medicine: A field that combines psychological and physical interventions to treat or prevent medical problems.

Coronary heart disease: Illness of the heart caused by a blockage in the coronary arteries.

Hypertension: Chronic high blood pressure.

Asthma: A medical problem marked by narrowing of the trachea and bronchi, which results in shortness of breath, wheezing, coughing, and a choking sensation.

Insomnia: Difficulty falling or staying asleep.

Migraine headache: A very severe headache that occurs on one side of the head, often preceded by a warning sensation and sometimes accompanied by dizziness, nausea, or vomiting.

Primary gain: In psychodynamic theory, the gain people achieve when their somatic symptoms keep their internal conflicts out of awareness.

Ulcer: A lesion that forms in the wall of the stomach or of the duodenum.

psychological factors affecting other medical conditions: Disorders in which biological, psychological, and sociocultural factors interact to cause or worsen a physical illness. Also known as psychophysiological disorders.

Secondary gain: In psychodynamic theory, the gain people achieve when their somatic symptoms elicit kindness from others or provide an excuse for avoiding unpleasant activities.

Type A personality style: A personality pattern characterized by hostility, cynicism, drivenness, impatience, competitiveness, and ambition.

Antigen: A foreign invader of the body, such as a bacterium or virus.

Muscle contraction headache: A headache caused by the narrowing of muscles surrounding the skull. Also known as tension headache.

Psychophysiological disorder: Disorder in which biological, psychological, and sociocultural factors interact to cause or worsen a physical illness. Also known as psychological factors affecting other medical conditions.

Conversion disorder: A disorder in which bodily symptoms affect voluntary motor and sensory functions, but the symptoms are inconsistent with known medical diseases.

Illness anxiety disorder: A disorder in which people are chronically anxious about and preoccupied with the notion that they have or are developing a serious medical illness, despite the absence of somatic symptoms. Previously known as hypochondriasis.