Lesson Starter Explain how the skin protects the body What are the secondary methods of protection

Cells Alive Fighting back!

Learn about when microbes get into our body Today we are going to.. Learn about when microbes get into our body

The immune system Sometimes microbes get past our first and second lines of defence and enter our body Could be through a cut or in food Our immune system deal with the invading microbes

War in our bodies In the battle against infection the immune system is a bit like sending in the troops . This is now war.

Phagocytosis One of the bodies methods of fighting infection is phagocytosis. This involves the engulfing (catching) and digestion ( breaking up) of micro-organisms by special cells called phagocytes. Phagocytes are a type of white blood cell

Phagocytosis Stage 2 Stage 1 The microorganism is detected and the phagocyte moves to attack it Stage 2 The phagocyte engulfs (catches) the microorganism

Stage 3 Enzymes (chemicals) in the phagocyte digest the micro-organism Phagocytosis Stage 3 Enzymes (chemicals) in the phagocyte digest the micro-organism Stage 4 The broken down microbes parts can be used by your body.

Phagocytosis

Draw In your jotters; draw 4 diagrams to show the stages of PHAGOCYTOSIS Microorganism detected and phagocytes moves towards it Phagocyte engulfs microorganism Enzymes digest microorganism Microbes broken down and used by body

Infection Battle In the battle against infection the Phagocytes are a bit like foot soldiers on patrol. They are on the ground and looking for any problems or trouble and ready to deal with it http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/human/defendingagainstinfectionrev4.shtml

Antibodies Antibodies are the MISSILES Antibodies are produced by white blood cells called lymphocytes Antibodies are molecules that the body produces to destroy microbes.

Antibodies Antibodies are Y shaped molecules that grab onto microbes

Antibodies Every microbe has a different shape so your body has to make new antibodies for every microbe that infects your body

Your body’s memory Your body keeps a memory of all the antibodies it has made in the past. This means if the same microbe returns you already have the correct antibodies and can produce more very quickly. This means that the same microbe cannot usually infect you twice which explains why most people only catch a disease once in their life.

Think.. Pair.. Share What is it ? If your immune system can tell the difference between what is yours and not yours then this can cause a problem. What is it ?

Homework research task: Page 29