Non specific response to disease 1)Define the term ‘immune response’ 2) Describe the primary defences in place against pathogens 3) Describe the structure of phagocytes and explain how they work

Non specific defence mechanisms The body has a range of defences to protect it against disease causing organisms, or pathogens. Make notes on the body outline to show these defences.

Phagocytes – secondary response Pathogens which manage to enter the body must be killed before they reproduce. And cause disease. This job is done by phagocytes & there are 2 types Neutrophils - most common. Made in bone marrow and travel in our blood. Do not live for long but are released in large numbers if an infection is detected. Macrophages – also made in bone marrow. Settle in body organs and develop into macrophages.

How phagocytes work Their role is to engulf and destroy pathogens. Step 1 - When the pathogen enters, our body realises it is foreign because it has markers on its outer membrane. These markers are Antigens. (Our own cells have these but our body recognises that they are our own and not a threat) Step 2 - Antibodies in our blood attach to the foreign antigens and the receptors on the phagocytes bind to the antibodies. Step 3 – As the phagocyte is now attached it will envelop the pathogen. Lysosomes now fuse to it and release enzymes which digest it. Step 4 – The digested invader is now harmless and released into the cytoplasm.

Explain why people who sustain burns often die from infections. Task Create a short video, using the flip cams, to show the action of phagocytosis. Explain why people who sustain burns often die from infections. Explain why the area around a wound often looks red.