The Immune System

Pathogens Are organisms or particles such as bacterium, fungus or viruses that have potential to cause disease. Your body is under constant attack from these pathogens

Your immune system tries to prevent these attacks and restore homeostasis It has three lines of defense

First line of Defense Skin Mucous membrane Saliva Blocks entry into your body

Counter attacks The second line of defense Now the pathogen has slipped through the first line and now your body counterattacks.

Some cells attack invaders Macrophages: a type of white blood cell that kills bacteria one at a time by ingesting them. They travel through the blood stream Neutrophils: another type of white blood cell that release a bleach like chemical to kill any bacteria

Natural Killer T cells: attack only cells that have been infected by microbes, not the microbes themselves. (lead attack against viruses)

Proteins that punch holes into bacteria once activated Complements Proteins that punch holes into bacteria once activated

Inflammation response You get cut Area releases chemical signals It gets red and inflames because this increases blood flow It promotes migration of the second line of defense

Raise body temperature When the counter attack occurs these white blood cells send messages to the brain to increase body temperature to try to prevent the growth of the pathogen

Now the third line you are sick Two types of response to different pathogens. Antibody-mediated response (bacteria) Cell mediated response (virus) cell is infected (produces killer T cells)

Antigens: are present on the surface of a pathogen the body then can recognize itself from nonself

Antibodies: Produced by plasma B cells they bind to antigens causing a clumping effect and flag others to eat them….