Immune system

What type of defence offers the first line of protection against invading organisms?

Name the barriers that protect us.

What is the function of the skin? How does it perform this function?

What is the function of mucus? How does it perform this function?

What happens to microbes swallowed into the stomach?

Are all bacteria in our bodies dangerous? Explain

When bacteria enter the body they are met by three non-specific responses, the inflammatory response, fever and phagosytic white blood cells. Describe how each one works.

 

 

White blood cells- The hunter killers of our body

White blood cells are constantly on a seek and destroy mission in our bodies. There are many different types of white blood cells formed by the red bone marrow and have a life span ranging from 2 hours to several years. Unlike red blood cells, white blood cells often leave the blood vessels to perform their duties in varies body tissues. White blood cells move like amoeba, changing the shape of their membrane and then flowing into it as shown on the right. They engulf and digest dead cells, bacteria and other foreign matter.

 

 
Unlike red blood cells, which travel at great speed through blood vessels, white blood cells roll along the surface of endothelial cells that form the inner wall of blood vessels.
The animation on the right shows how white blood cells operate. They can move through tiny holes in the walls of the smallest blood vessels(capillaries) where they seek and destroy dead cells and foreign matter. Often children who play with wood get splinters in their hands. After a while puss forms around the splinter and the region becomes inflamed with a deep red colour. The puss forms as a result of white blood cells moving into the area to engulf and digest the wood and bacteria that have entered the body. The inflammation occurs as the blood vessels dilate to increase blood flow to the damaged region.

 

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