How do we fight disease? Immune System

Microorganisms that make us sick are called pathogens Diseases caused by pathogens are called infectious diseases

Types of pathogens Bacteria Viruses: Fungi: Protists: example: strep, tetanus Viruses: colds, flu Fungi: athlete’s foot & ringworm Protists: amoebic dysentery

How are pathogens spread? A. Contact with an infected person 1. Direct contact: kissing, shaking hands 2. Indirect contact: sneezes B. Contaminated food, water & soil C. Contaminated objects D. Infected animals

Body Defenses Barriers (First Line of Defense) 1. Skin 2. Breathing passages Mucus Cilia 3. Mouth & stomach Saliva Stomach acid

If something gets through the barriers: Invaders cause damage to cells which trigger an inflammatory response (Second Line of Defense) Fluid & white blood cells leak into tissues to fight the pathogens Phagocyte- engulfs pathogens and digests them Fever- higher temperature kills pathogens

Immune System (3rd Line of Defense) If pathogen is bad enough for a fever, then the 3rd line of defense is triggered, the immune response Immune system has cells to target specific pathogens

Immune System Cells T-Cells- identify the pathogens B-Cells- produce antibodies in response to the antigens on the pathogen to fight each different type of pathogen Go to p. 571 sketch the diagram in your book explaining how the T cells and the B cells fight off infection. (yes, I want you to copy the exact diagram and labels)

Preventing Infection Immunity: the bodies ability to destroy pathogens before the cause the disease Two types: Active Passive

Active Immunity your own body produces antibodies in response to the presence of a pathogen When you get sick and the T & B cells fight off the pathogen, the remember it, if it comes back they are ready (chicken pox) OR Vaccination- when you are vaccinated some of the disease is injected into you to trigger an immune response

Passive immunity When antibodies to fight disease come from some place other than your own body Example: babies get antibodies through breast milk & from mothers blood before birth