35.4 Immune System Disorders Lesson Overview 35.4 Immune System Disorders

THINK ABOUT IT A healthy immune system accurately distinguishes “self” from “other” and responds appropriately to dangerous invaders in the body. Sometimes, however, the immune system attacks the wrong targets. Other times, the immune system itself is disabled by disease. What happens in these cases?

When the Immune System “Misfires” The immune systems of some people overreact to harmless antigens, such as pollen, dust mites, mold, and pet dander. A strong immune response to harmless antigens can produce allergies, asthma, and autoimmune disease. .

Allergies Antigens that cause allergic reactions are called allergens. Pet dander, dead skin shed from cats and dogs, is a common allergen.

Allergies When allergens enter people affected by allergies, they trigger an inflammatory response -mast cells release histamines. If this response occurs in the respiratory system, it increases mucus production and causes sneezing, watery eyes, a runny nose, and other irritations. Drugs called antihistamines help relieve allergy symptoms by counteracting the effects of histamines. Holistic Approach-eat local honey

Asthma Allergic reactions in the respiratory system can create a dangerous condition called asthma. Asthma is a chronic disease in which air passages narrow, causing wheezing, coughing, and difficulty breathing. Both hereditary and environmental factors influence asthma symptoms. Asthma attacks can be triggered by respiratory infections, exercise, emotional stress, and certain medications. Other triggers include cold or dry air, pollen, dust, tobacco smoke, pollution, molds, and pet dander.

Asthma Severe asthma can lead to permanent damage or destruction of lung tissue if not treated properly There is no cure, but one can sometimes control the condition. If the attacks are caused by an allergen, tests can identify which allergens cause the problem. Inhaled medications can relax smooth muscles around the airways and relieve asthma symptoms.

Autoimmune Diseases Sometimes a disease occurs in which the immune system fails to properly recognize “self,” and it attacks cells in the body like they were pathogens. When the immune system attacks the body’s own cells, it produces an autoimmune disease. Examples of autoimmune diseases are Type I diabetes, rheumatoid arthritis, and lupus.

Autoimmune Diseases In Type I diabetes, antibodies attack insulin-producing cells in the pancreas. In rheumatoid arthritis, antibodies attack connective tissues around the joints. Lupus is an autoimmune disease in which antibodies attack organs and tissues leading to areas of chronic inflammation throughout the body.

Autoimmune Diseases Some autoimmune diseases can be treated with medications that alleviate specific symptoms. For example, people with Type I diabetes can take insulin. Other autoimmune diseases are treated with medications that suppress the immune response. However, these need monitored.

When the Immune System “Misfires” How can misguided immune responses cause problems?

When the Immune System “Misfires” How can misguided immune responses cause problems? A strong immune response to harmless antigens can produce allergies, asthma, and autoimmune disease. When the immune system attacks the body’s own cells, it produces an autoimmune disease.

HIV and AIDS During the late 1970s, physicians reported serious infections by microorganisms that didn’t normally cause disease. Healthy people suffer from pneumonia, rare forms of skin cancer, & fungal infections of the mouth and throat. Doctors concluded that these patients must have weakened immune systems. Diseases that attack a person with a weakened immune system = opportunistic diseases.

HIV and AIDS Doctors ultimately recognized that these illnesses were symptoms of a new disorder they called acquired immunodeficiency syndrome (AIDS). In 1983, researchers identified the cause of AIDS—a virus they called human immunodeficiency virus (HIV).

HIV HIV is deadly for two reasons. First, HIV can hide from the defenses of the immune system. Second, HIV attacks key cells within the immune system, leaving the body with inadequate protection against other pathogens.

HIV HIV is a retrovirus that carries its genetic information in RNA, rather than DNA. When HIV attacks a cell, it binds to receptor molecules on the cell membrane and inserts its contents into the cell.

Target: T Cells HIV travels through the blood, where it binds to helper T cells—the command centers of the specific immune response. Once inside the cell, the virus directs the cell to produce many new viruses. These new viruses are quickly released back into the blood, where they infect new cells.

Target: T Cells HIV destroys T cells, crippling the ability of the immune system to fight HIV and other pathogens. Monitoring progression of HIV by counting helper T cells. The fewer helper T cells, the more susceptible to other diseases. When an HIV-infected person’s T cell count reaches about 1/6 the normal level, he/ she is diagnosed with AIDS.

HIV Transmission HIV is not easily transmitted. *NOT ~coughing/sneezing/sharing clothes/casual contact. *IS ~contact with infected blood/semen/vaginal secretions/breast milk. The four main ways that HIV is transmitted: sexual intercourse with an infected person sharing needles with an infected person contact with infected blood or blood products From infected mother to child: pregnancy/birth/ breast-feeding.

Preventing HIV Infection You choose behaviors that reduce your risk of becoming infected with HIV. Committed relationship People who share needles for drugs are at an increased risk. People who have sex with drug abusers increase risk. Before 1985, HIV was transmitted to some patients through transfusions of infected blood or blood products. eliminated by screening blood for HIV antibodies & by discouraging potentially infected individuals from donating blood.

Preventing HIV Infection This graph shows the increase in cases 13-24-year-olds living with AIDS in the United States.

Can AIDS Be Cured? At present, there is no cure for AIDS. New drugs, however, make it possible to survive HIV infection for years. HIV mutates & evolves rapidly. The virus has evolved into many strains that are resistant to most drugs used against them. No one has developed a vaccine that offers protection for any length of time.

Can AIDS Be Cured? To control use a combination of expensive drugs. Drugs interfere with the enzymes HIV uses to insert its RNA into a host cell No cure for HIV

HIV and AIDS What causes AIDS and how is it spread?

HIV and AIDS What causes AIDS and how is it spread? In 1983, researchers identified the cause of AIDS—a virus they called human immunodeficiency virus (HIV). The only no-risk behavior with respect to HIV transmission is abstinence from sexual activity and intravenous drug use.