Disorders

Allergies Body fights of a harmless thing that it perceives it as a threat 2 types: Immediate hypersensitivity Triggered by release of histamine leaky caps = runny nose, watery eyes Symptoms show within seconds Anaphylactic shock can cause death; must be treated with epinephrine Delayed hypersensitivity Triggered by the release of lymphokines from helper T cells Symptoms show in 1–3 days (ie- poison ivy)

Immunodeficiencies Little to no B or T immune cells May be born with it or acquire it Example: AIDS (Acquired Immune Deficiency Syndrome) - interferes with helper T cells Caused by HIV (Human Immunodeficiency Virus)

Autoimmune Diseases The immune system does not distinguish between self and nonself antigens The body produces antibodies and T lymphocytes that attack its own tissues Examples: Multiple sclerosis - white matter of brain and spinal cord are destroyed Type I diabetes - destroys pancreatic cells that make insulin Rheumatoid arthritis- destroys joints

Development of Lymphatic System Except for thymus and spleen, the lymphoid organs are poorly developed before birth Develop immune response at birth No working lymphocytes yet If lymph vessels are surgically removed there will be severe edema but eventually grow back Less efficient with age