Transcript Document
31.2 Immune System KEY CONCEPT The immune system consists of organs, cells, and molecules that fight infections. 31.2 Immune System • The immune system is the body system that fights off infection and pathogens. 31.2 Immune System • Think of your body as a heavily guarded castle. When pathogens invade they must break down the outer wall or find a way around it. If the intruders get past the physical barriers, they must face your body’s fighters in hand-tohand combat. • Invaders are winning= you are sick • Your body is winning= you are healthy 31.2 Immune System What is our first line of defense? • SKIN!!!!!!! – Cuts and wounds are entry points What are the other entry points? • • • • • Eyes Nose Ears Mouth Excretory Organs (lungs) 31.2 Immune System – Skin is a physical barrier to infection - It is your first line of defense! – Mucous membranes in these openings trap pathogens entering the body. – The circulatory system transports immune cells. 31.2 Immune System SKIN • First line of defense against pathogens – Protection from infection – Oil glands in skin - Inhibit the growth of bacteria 31.2 Immune System • How do we heal? *Discuss with your table the order in which a cut heals. • • • • • • Cut yourself Bleed Form blood clot Blood clot dries out- Scab is formed Skin cells divide and multiply- (mitosis) Scab falls off 31.2 Immune System Six main types of white blood cells 1) phagocyte- Destroys viruses, bacterium, and fungi by engulfing them Ex: macrophage 31.2 Immune System 2) T cells- Destroy body cells that are infected 3) B cells- Produce proteins that inactivate pathogens that haven't infected body cells yet 31.2 Immune System 4) Complement Proteins: made by white blood cells, and weaken pathogen’s cell membrane allowing water in so it will burst 31.2 Immune System 5) Antibodies: made by B cells • Attack pathogens by “binding” themselves to the pathogen to prevent them from attacking healthy cells • Cause pathogen’s to clump, making it easier for phagocytes to engulf and destroy 31.2 Immune System 6) Interferons: produced by body cells infected by a virus • Stimulate uninfected body cells to produce enzymes that will prevent viruses from entering and infecting them • ***If a virus can’t enter it- it can’t reproduce!