Fighting Diseases: The Immune System

How is Bacteria and other Diseases Spread? Moisture droplets in air Dust Direct body to body contact (skin, fluids, etc) Fecal contamination Animal bites Wounds

Why do we need an Immune System? Many bacteria are pathogens  they are disease-causing organisms

Why do we need an Immune System? An immune system defends our body against pathogens and build up an immune response for future incidents

Why do we need an Immune System? Tonsil – filter out infectious organisms Thymus – contain specialized WBCs Liver – its WBCs removes organisms from blood

Why do we need an Immune System? Spleen – removes weird cells from blood Bone marrow – production of WBC Lymph nodes – filters; produces antibodies

Immune System Response: 1st Line of Defense - Structural Skin: keeps organisms and allergens from entering Sweat : contains salts that are poisonous to bacteria

Immune System Response: 1st Line of Defense - Structural Lysozyme: enzyme in tears, saliva, mucus, perspiration; digests bacterial cell walls Cilia in respiratory passages: mucus helps trap bacteria Stomach acid: low pH kills pathogens

Immune System Response: 2nd Line of Defense – Cellular The Lymphatic System  network of organs, vessels and lymph nodes throughout body Vessels transport fluid lymph (has lymphocytes, also known as white blood cells) from lymph nodes to rest of body

Immune System Response: 2nd Line of Defense – Cellular When bacteria invades the body, WBC become activated as macrophages and seeks out the bacteria = engulf them and digest them using enzymes

Immune System Response: 3rd Line of Defense Antibodies attack invaders  GOOD Antigen is a foreign material that attacks the body  BAD.

Immune System Response: 3rd Line of Defense Antibodies signal macrophages to destroy a particular antigen Memory cells remember how to produce specific antibodies for future invasions.

Types Of Immunity: ACTIVE IMMUNITY Lasting protection against an invader through the manufacture of antibodies (ie. previous infection, some vaccinations)

Types Of Immunity: PASSIVE IMMUNITY: Temporary protection against a particular disease by the direct introduction of antibodies (ie. mom to baby, vaccinations)

Types Of Immunity: VACCINE: Dead or weakened bacteria; body reacts to create to antibodies.