Chapter 19 Fighting Disease

 Objectives:  Explain the cause of infectious disease and identify the kinds of organisms that cause disease  Describe methods in which pathogens enter the body Section 1: Infectious Disease

 Organisms that cause disease = pathogens  A disease that can pass from one organism to another = infectious disease  Infectious diseases are caused by pathogens Disease and Pathogens

 4 major groups of human pathogens: 1.Bacteria 2.Viruses 3.Fungi 4.Protists  Each infectious disease is caused by a specific pathogen Disease and Pathogens

 Examples:  Bacteria causes strep throat  Viruses cause the flu  Fungus causes athlete’s foot  A protist causes malaria Disease and Pathogens

 In 1860’s Louis Pasteur showed microorganisms cause certain diseases  Pasteur developed a method of heating foods to kill microorganisms = pasteurization  Influenced British surgeon Joseph Lister to sterilize his hands and instruments before surgery AND  After surgery to cover wounds with treated bandages Disease and Pathogens

Surgery in the 1800’s

Modern Surgery

 You can become infected by a pathogen in one of several ways: 1.By another person 2.By contaminated objects 3.An animal bite 4.The environment How Diseases are Spread

Person to Person Transfer  Direct physical contact:  Kissing  Hugging  Shaking hands  Indirect contact:  Sneezing  Coughing

 Food  Water  Towels  Silverware  Stepping on contaminated nails Contaminated Objects

 Rabies  Lyme disease  Rocky Mountain spotted fever Animal Bites

 The bacteria that causes tetanus lives in soil and water  The bacteria that causes botulism lives in soil Pathogens from the Environment

 Objectives:  Identify the body's barriers against pathogens  Describe the role of the inflammatory response in fighting disease  State how the immune system responds to pathogens.  Describe HIV and list the ways it can be spread Section 2: The Body’s Defenses

 Barriers such as the skin, breathing passages, mouth, and stomach trap and kill most pathogens with which you come into contact Barriers That Keep Pathogens Out

 Chemicals in oil and sweat can kill pathogens  Pathogens can fall off with dead skin  Washing with soap and water decreases pathogens  Scabs over cuts prevent pathogens from entering the body The Skin

 Mucus and cilia in the nose, pharynx, and bronchii trap and remove pathogens that enter the respiratory system  Sneezing and coughing force pathogens out of your body The Breathing Passages

 Saliva and stomach acid kill most pathogens that you swallow The Mouth and Stomach

 In the inflammatory response, fluid and certain types of white blood cells leak from blood vessels into nearby tissues.  The white blood cells then fight the pathogens  White blood cell that engulfs and destroys pathogens = phagocyte General Defenses

 The cells of the immune system can distinguish between different kinds of pathogens.  The immune system cells react to each kind of pathogen with a defense targeted specifically at that pathogen  White blood cells that recognize pathogens = lymphocytes The Immune System

 Distinguish between different kinds of pathogens  Molecules on cells the immune system recognizes as either part of your body or outside your body = antigens T Cells

 Produce chemicals that help destroy pathogens  Chemicals are called antibodies  Each B cell produces only 1 specific antibody B Cells

 AIDS = a disease caused by a virus that attacks the immune system  Caused by the HIV virus  Attacks and destroys T cells AIDS, a Disease of the Immune System

 Objectives:  Define and explain active immunity  Define and explain passive immunity  Identify some strategies for staying healthy Section 3: Preventing Infectious Disease

 The body’s ability to destroy pathogens before they can cause disease = immunity  When a person’s own immune system produces antibodies in response to the presence of a pathogen = active immunity Active Immunity

 T cells and B cells remember the antigens they come into contact with  When they encounter that antigen again the immune response is very quick and you usually don't get sick How Active Immunity is Produced

 The process by which harmless antigens are deliberately introduced into a person’s body to produce active immunity = vaccination  The substance used in the vaccination = vaccine  Usually contains dead or weakened forms of the pathogen Vaccination

 When a person is given the antibodies = passive immunity  Occurs when the antibodies that fight the pathogen come from another source rather than from the person’s own body Passive Immunity

 Don’t share items that might carry pathogens like toothbrushes, drinking straws, and silverware  Wash hands before eating and after using the bathroom  Cover your mouth when sneezing and coughing  Get 8 hours of sleep every night  Eat a well-balanced diet  Get regular exercise Staying Healthy

 Define an allergy  Explain how diabetes affects the body  Explain how cancer affects the body Section 4: Noninfectious Disease

What are Noninfectious Diseases?  Noninfectious disease – diseases not spread from person to person  Not caused by microorganisms

 Allergies – disorder in which the immune system is overly sensitive to a foreign substance  Allergen – any substance that causes an allergy  Histamine – chemical that is responsible for the symptoms of an allergy Allergies

Asthma  Asthma – disorder in which the respiratory passages narrow significantly  Short of breath  Brought on by stress, exercise, allergies

 Diabetes – a condition where pancreas fails to produce insulin or body cells can’t use it properly  Insulin – a chemical that allows body cells to take in glucose from blood  Person excretes glucose in urine  Body cells do not have enough glucose for energy Diabetes

Insulin Pump

Effects of Diabetes  Lose weight  Weak  Hungry  Urinate frequently  Feel thirsty  Long-term effects

 Type I  More serious  Begins in childhood  Type II  Develops during adulthood  May not need to take insulin Two Forms of Diabetes

 Cancer – disease in which cells divide uncontrollably  Tumors – abnormal tissue masses  Often caused by carcinogens – a substance or a factor in the environment that can cause cancer Cancer