BODY DEFENSES AND DISEASE The 5th Guy

CAUSES OF DISEASE Noninfectious Disease  When you have a disease, your normal body functions are disrupted.  Noninfectious disease ARE NOT spread from person to person  CAUSES:  Smoking  Lack of physical activity  High-fat diet

CAUSES OF DISEASE Infectious Disease  Infectious disease CAN be passed from one living thing to another.  CAUSED BY:  Pathogens: virus, microorganism or other organisms that cause disease.

PATHWAYS TO PATHOGENS  AIR: Some pathogens travel through the air *Example: a single sneeze  CONTAMINATED OBJECTS: If you share objects with an infected person, you can become SICK! *Example: contaminated doorknobs, keyboards, combs, and towels  PERSON TO PERSON: Some pathogen are spread by direct person *Example: kissing, shaking hands or The 5th Guy 2

PATHWAYS TO PATHOGENS  ANIMALS: Some pathogens are carried by animals  Example: humans can get a fungus called ringworm from handling an infected dog.  FOOD AND WATER: Drinking water in the United States is generally safe. But water lines can break allowing germs to enter.  Bacteria growing in foods and beverages can cause illnesses  Example: meat, fish, and eggs that are not cooked enough

PUTTING PATHOGENS IN THEIR PLACE  PASTEURIZATION  During the mid-1800s, Louis Pasteur discovered that microorganism cause wine to spoil.  Pasteur devised a method of using heat to kill most of the bacteria in wine and milk.  VACCINES AND IMMUNITY  In the late 1700s, no one knew what a pathogen was.  Edward Jenner studied a disease called smallpox.  He observed that people who had been infected with cowpox seemed to have protection against smallpox.

PUTTING PATHOGENS IN THEIR PLACE  ANTIBIOTICS  Have you ever had strep throat?  An antibiotic is a substance that can kill bacteria or slow the growth of bacteria  Viruses, such as those that cause colds, are not affected by antibiotics.  Antibiotics can kill only living things.  A virus is NOT a living thing. The 5th Guy - Flu

Vaccines  A substance prepared from killed or weakened pathogens.  Stimulates the body to produce immunity.  Used to trigger the body to make memory cells for a specific pathogen  How could a vaccine prevent the spread of disease?  How is being vaccinted similar to being infected with a disease?  How is it different?

YOUR BODY’S DEFENSES FIRST LINE OF DEFENSE  For a pathogen to harm you, it must attack a part of your body.  YOUR BODY’S FIRST LINE OF DEFENSE IS YOUR SKIN!  Your skin is made of many layers of fat cells. The outermost layers are dead.  As a result, many pathogens that land on your skin have difficulty finding a live cell to infect

YOUR BODY’S DEFENSES FAILURE OF THE FIRST LINES OF DEFENSE  Sometimes, skin is cut or punctured and pathogens can enter the body.  THE BODY ACTS QUICKLY!  Blood flows to the injured area  Cell parts in the blood called platelets, which help seals the wound.  The increased blood flow also brings cells that belong to the IMMUNE SYSTEM.

CELLS OF THE IMMUNE SYSTEM  The immune system consists mainly of three kinds of cells. MACROPHAGE BIG EATERS  Engulf and digest microorganisms or viruses.  If only a few microorganism or viruses have entered a wound, the macrophages can easily STOP THEM.  It alerts the rest of the immune system of invaders

CELLS OF THE IMMUNE SYSTEM Lymphocytes - T cells and B cells On the surface of each lymphatic cell are receptors that enable them to recognize foreign substances. These receptors are very specialized - each can match only one specific antigen. Helper T Cell Helper T cells are the major driving force and the main regulators of the immune defense. Their primary task is to activate B cells and killer T cells. The killer T cell is specialized in attacking cells of the body infected by viruses and sometimes also by bacteria. It can also attack cancer cells.

CELLS OF THE IMMUNE SYSTEM B Cells  The B lymphocyte cell searches for antigen matching its receptors. If it finds such antigen it connects to it, and inside the B cell a triggering signal is set off.  The plasma cell is specialized in producing specific protein, called an antibody, that will respond to the same antigen that matched the B cell receptor. Antibodies are released from the plasma cell so that they can seek out intruders and help destroy them.

Challenges to the Immune System  Allergies – over reaction to foreign antigens that are not dangerous to most people. (ex. Peanuts, penicillin, mold, etc.)  Cancer – a group of diseases in which cells divide at an uncontrolled rate. (ex. Skin cancer)  Immune Deficiency – HIV/AIDs; specifically infects the T-cells.  Auto-immune Diseases – cells mistake body cells for foreign antigens; ex rheumatoid arthritis  What is the differenece between an allergy and an autoimmune disease?  In an autoimmune disease, the immune system attacks the body’s own cells. In an allergy, the immune system reacts to foreign cells that are for the most part harmless; such as pollen, foods or medicine.