Chapter 40 “The Immune System” 40.1 “Disease” Objective: Define the term “disease” Describe “Germ Theory” & “Koch’s Postulates” Discuss disease Transmission & Prevention.

Introduction (Do not write) How would you define an infection? Sickness, contamination of some sort. By what? Bacteria, or some “other” disease causing organism. How does the human body become infected? Cuts, breathing, eating

Disease A disease is any change, other than injury, that disrupts “normal” body functions. Some are inherited (hemophilia), some are caused by environment, others by bacteria, viruses, or fungi.

Pathogens Infect the body Cause disease Virus Bacteria Malaria Parasite

The Germ Theory Observations made by Louis Pasteur & Robert Koch concluded that diseases were caused by “germs”, rather than “evil spirits”. Koch developed guidelines to identify microorganisms that caused diseases

Agents of Disease Ideal conditions for pathogen growth - your body! Most are harmless Bacteria release toxins which make you sick Viruses (non-living) invade cells and eventually cause them to pop

Transmission Coughing, sneezing, physical contact. Contaminated food & water. Infected animals. Vectors - animals that carry the disease causing organism (ticks, mosquitoes)

Fighting Pathogens Prevention Drugs Antibiotic – attacks cell wall of bacteria Do not work against viruses – no cell wall

40.2 “The Body’s Defense System” Objective: Identify Non-Specific & Specific Defenses. Define/describe the term Immunity.

Introduction (do not write) With so many pathogens, why aren’t you sick all the time? Your body has a protective system; a series of defenses that guard against disease. Like walls that act as barriers & security guards trained to spot invaders.

Immune System Primary defense against pathogens Nonspecific defenses Block out everything Specific defenses Attack a specific pathogen

Nonspecific Defenses First line of defense = the skin, mucus, sweat, stomach acid Skin is the most important nonspecific defense.

Inflammatory Response Second line of non-specific defenses Pathogens may enter body through a cut Area swells, gets red WBC released into injured area Pathogens vs. WBC

Inflammatory Response Skin Wound Bacteria enter the wound WBCs move into the area and engulf the bacteria and cell debris Capillary

Specific Defenses Powerful defense against a “specific” pathogen. S. defenses produce immunity against pathogens. Two types of immunity: Anti-body & Cell Mediated Immunities.

Antibody Immunity Molecules on surface of pathogens called antigens Antigens trigger immune response B cells (WBC) make proteins called antibodies which stick to antigens

Vaccines First vaccine was in late 1700s against small pox Weakened pathogen is injected into body Body mounts an immune response without getting sick Immune system develops a memory of the pathogen = permanent immunity

Cell-Mediated Immunity Powerful Immune System weapon = Killer T cell. Kill infected body cells. Can cause transplantation rejection. Helper T cells & Suppressor T cells.

Immune Disorders Two main types of disorders: Auto-Immune (overreaction) & Weakening of I.S. (AIDS). Allergies: overreaction to antigen in environment. Histamines are released = inflammatory response. Asthma

Auto-Immune Diseases Immune System attacks body’s own cells. Ex - Rheumatoid arthritis & Multiple sclerosis

HIV/AIDS HIV attacks T cells Kills T cells = kills immune system New viruses leaving an infected T cell

40.3 “Cancer” Objective: Define Cancer. Identify causes of Cancer.

Cancer 2nd leading cause of death in U.S Cancer is uncontrollable cell growth which forms malignant tumors. Caused by mutations, or changes in DNA.

Causes Viruses HPV is sexually transmitted and may lead to reproductive cancers. Hepatitis leads to liver cancer.

Causes of Cancer... Radiation = UV light from the Sun. Chemicals = carcinogen Genetics Treatment: surgeries, chemotherapy