Chapter 40

 Helps protect body from disease  Collects fluid lost from blood vessels and returns fluid to circulatory system

 White Blood Cells  Thymus  Spleen  Lymph Nodes  Lymph Vessles  Bone marrow  Blood vessels

 Disease – Any change, other than injury, that disrupts the normal function of the body ◦ Pathogens – disease causing agents

 Germ Theory of Disease –diseases are caused by microorganisms called germs ◦ How do we know what causes a disease? Ex. Lyme disease

 Koch’s Postulates ◦ Developed by Koch ◦ Series of rules used to identify the microorganism that causes a disease ◦ Identification is the first step to a cure

 Koch’s Postulates (page 1032) ◦ Pathogen should be found in body of a sick organism and not in a healthy ◦ The pathogen must be isolated and grown in lab in pure cultures ◦ The cultured pathogens, when placed in a new host, should cause same disease as the original host ◦ When isolated from the second host, it should be identical to original pathogen

 Agents of Disease ◦ Pathogens cause disease by  Destroying cells  Releasing toxins  Disrupting bodily functions  Remove nutrients  Block blood flow

◦ Viruses  Tiny particles  Invade cells and replicate  Attach to cell and insert genetic information  Common cold, influenza, smallpox, and warts Chicken Pox

Human papilloma virus

◦ Bacteria  Cause of disease  Breaking down tissues  Releasing toxins  Streptococcus, diphtheria, botulism, and anthrax

◦ Protists  Malaria - mosquitoes  Trypansoma – contaminated blood  Amebic Dysentery – contaminated water Malaria

◦ Worms  Tapeworms and hookworms ◦ Fungi  Athlete’s foot  Ringworm Wuchereria bancrofti (worm)

 Spreading Disease ◦ Direct/Indirect Contact ◦ Contaminated food and water  Food poisoning ◦ Infected Animals  Vectors – animals that carry pathogens

 Fighting Infectious Diseases ◦ Antibiotics – compounds that kill bacteria  Penicillin – 1928 Alexander Fleming

 Fight infection by making cells that inactivate foreign substances or cells which we call immunity

 1. Nonspecific Defenses ◦ Physical Barriers ◦ Chemical Barriers

◦ First line of defense – Keeps pathogens out of the body  Skin – most important nonspecific defense  Mucus, sweat, and tears – contain lysozyme  Lysozyme – enzyme that breaks down the bacteria’s cell wall

◦ Second line of defense  Inflammatory response – Reaction to tissue damage caused by injury or infection  WBC or phagocytes kill bacteria  Fever – Increased body temperature  Slows or stops bacteria growth  Increases heart rate

◦ Interferon – a group of proteins that help healthy cells resist viral infection

 Immune response – Specific defenses that attack pathogen  Antigen – Substance from virus/ pathogen that triggers the response  T cells – T Lymphocytes  B cells – B Lymphocytes

 Humoral Immunity – Response to antigens and pathogens in body fluids  B Cells – Identify antigen and quickly multiply  Plasma cells – release antibodies  Antibodies – proteins that recognize and bind to antigens  Memory B cells

◦ Antibody Structure  Y shaped amino acid  Two identical binding sites  100 million different antibodies

◦ Cell-Mediated Immunity – Response to abnormal cells and pathogens inside living cells  T cells – divide during infection or cancer  Killer T cells – kill pathogen  Helper T cells – make memory T cells  Suppressor T cells – Shutdown killer T cells  Memory T cells

 Body attacks foreign organs  Recipients must take drugs to resist rejection

 1. Acquired Immunity ◦ Edward Jenner developed the first vaccine  Smallpox

 2. Active Immunity  Vaccination – injection of weakened or mild form of virus  Long time response

 3. Passive Immunity – Exposure to antibodies of an animal that has had an infection  Colostrum from mother’s milk  Shorter time protection

 Allergies – An overreaction to antigens on mast cells ◦ Allergens - Pollen, dust, mold, and bee sting ◦ Histamines – Chemicals released by mast cells that cause inflammation

 Asthma – Chronic respiratory disease ◦ Causes - Infection, exercise, stress, medication, cold air, pollen, dust, tobacco smoke, pollution, molds, and pet dander

 Autoimmune Diseases – Immune system attacks it’s own cells ◦ Type I Diabetes ◦ Rheumatoid arthritis ◦ Myasthenia gravis ◦ Multiple sclerosis

 AIDS – Acquired immunodeficiency syndrome ◦ Viral infection that attacks helper T cells ◦ Immune system breaks down

◦ HIV – Human immunodeficiency virus  Retrovirus  Destroys helper T cells  Forces the human cells to make more HIV

◦ Transmission  Sexual contact  Shared needles  Contact with blood  Mother to child

 Maintaining Health ◦ Healthy Diet ◦ Exercise and Rest ◦ Abstaining from Harmful Activities ◦ Regular Checkups