The immune system
The body has a second line of defence to stop or minimise infection. This is called the The body's defence system against entry of any foreign body, including pathogens and agents such as pollen grains. The role of the immune system is to prevent disease. and mainly consists of two types of white blood cells:
- Cells, such as white blood cells, that engulf and absorb waste material, harmful microorganisms, or other foreign bodies in the bloodstream and tissues.
- White blood cells which attack pathogens by producing antibodies.
Phagocytes
About 70 per cent of the white blood cells are phagocytes. They are part of the body鈥檚 immune system, but they do not produce antibodies. Instead, they ingest and destroy pathogens such as bacteria.
Phagocytes recognise Microorganisms that are harmful to humans. and destroy them by the process of The process of the ingestion of bacteria or other material by phagocytes.. Phagocytosis involves the engulfing of pathogens and their destruction by digestive enzymes contained in lysosomes.
The phagocyte's membrane surrounds the pathogen and engulfs it in a A fluid-filled space within a cell. Depending on the type of cell this might store and transport nutrients or waste material.. Enzymes found inside the cell then break down the pathogen in order to destroy it. As phagocytes do this to all pathogens that they encounter, they are called non-specific.
During the immune response phagocytes also release cytokines (proteins that acts as a signalling molecules) which attracts more phagocytes to the site of infection.
Phagocytes pass through blood vessel walls into the surrounding tissue