Antigen A substance on the surface of a pathogen that triggers an immune response is called an Antigen (Germ’s fingerprint)

Two Divisions of the Immune System Humoral Immunity Cell-mediated Immunity Antibodies mark infected cells for death Cells attack infected cells

Cells of the Immune System Two types of cells recognize specific antigens: B Lymphocytes and T Lymphocytes B-Cell T-Cell

Humoral Immunity B-Cells - provides immunity against pathogens found in body fluids.

Humoral Immunity Plasma Cell Antibodies B-Cell Pathogens (Bacteria, Virus, Fungi, Worms, Foreign Proteins) 3. B-cells become Plasma cells, which produce antibodies against the antigen Antibodies bound to pathogen 2. B-cell recognizes antigen on pathogen 4. Antibodies bind to the pathogen, marking it for death 1. Pathogen invades the body

Antibody Plasma cells produce antibodies Antibodies circulate in the bloodstream and attack the pathogen causing the infection

Antibody Antibodies are proteins that recognize and bind to antigens

Antibody Antigen-Binding Sites The site that the antibody binds to the antigen is called the antigen-binding site

Memory Cells Some B-cells become memory cells, which are the antibody factory pre-programmed to respond to a returning antigen (i.e. vaccination)

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Cell-Mediated Immunity T-Cells - provide a defense against abnormal cells and pathogens inside living cells

Cell-Mediated Immunity T-Cell Killer T Cell Virus-infected cell Pathogens (Bacteria, Virus, Fungi, Worms, Foreign Proteins) Helper T-Cell Cell lysis & death 2. Helper T cells activate Killer T cells 1. Pathogen invades the body 3. Killer T cells attack infected cells and quickly kill them

Organ Transplant Cell-mediated immunity makes the acceptance of organ transplants difficult Your immune system recognizes the transplanted organ as foreign and attacks it - Rejection

Organ Transplant To prevent organ rejection, doctors search for a donor with cell markers close to that of the recipient Organ recipients take anti-rejection drugs to suppress cell-mediated immune response

Summary of the Specific Defenses Humoral Immunity Cell-Mediated Immunity Mechanism Antibodies Immune Cells Cell Type B-cells T-cells Mode of Action Circulating antibodies Cell-to-Cell contact Purpose Defense against extracellular pathogens Defense against intracellular pathogens

Bacteria-related diseases Lyme Disease- Rash that leads to muscle aches Strep Throat- Fever, sore throat, swollen glands Tuberculosis- Fatigue, weight loss, chronic cough Do not write, just listen

Virus-related diseases Common cold/flu: Sneezing, sore throat, aches Hepatitis A-C: Jaundice, fatigue, diarrhea Chickenpox: Fever and weakness, rash AIDS: Helper T- cells are destroyed Do not write, just listen

What is immunity? Immunity - Resistance to a disease-causing organism or harmful substance Two types: Active Immunity Passive Immunity

Exposure to actual disease Active Immunity Your body produces its own antibodies Plasma cell Planned exposure to a form (weakened or killed) of the antigen = Vaccination Exposure to actual disease

Passive Immunity Antibody is produced by other animals and introduced into your body by injection into the bloodstream or naturally (mother’s milk).

How long does active immunity last? Some disease-causing viruses mutate into new forms that our body doesn’t recognize, requiring annual vaccinations, like the flu shot Booster shot - reminds the immune system of the antigen Others last for a lifetime, such as chicken pox Do not write, just listen

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Antibiotics Compounds that kill bacteria without harming other cells Prevents cell wall formation Doesn’t affect viruses since they have no cell wall

Immune System Disorders - Allergies Immune system sees harmless foreign particles as a threat and launches an immune response Sneezing, runny nose and watery eyes

Immune System Disorders - Asthma Chronic respiratory disease Air passages become narrower Wheezing, coughing, & difficulty breathing

Immune System Disorders - AIDS (Acquired Immune Deficiency Syndrome) HIV (Human Immunodeficiency Virus) is the virus that causes AIDS Specifically targets and kills Helper T-Cells

Immune System Disorders - AIDS Host cell produces new viral particles, which infects new helper T cells Virus enters the host cell and inserts it’s RNA into the host DNA

Tranmission of HIV Any form of sexual intercourse Sharing needles or syringes Contact with blood/body fluids From an infected mother to her child during pregnancy, birth, or breast- feeding

AIDS - The Modern Plague HIV cripples your immune system Common diseases become life-threatening Currently no cure, only treatment

AIDS - The Silent Spread An estimated 34.2 million people worldwide have HIV (2011) 2.5 million new HIV infections in 2011 Sub-Saharan Africa is a largest region with HIV positive people Do not write, just listen

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