What is phagocytosis and what steps are involved?

Phagocytosis is the name given to the process where phagocytes (a type of white blood cell found in blood) will ingest invading pathogens or large particles and digest their contents. . 1.      The pathogens will have managed to get past the body’s first line of defence (eg. skin, mucosal layer of airways, tears) and enter the body’s tissues. 2.      The cells which are in contact with the invading pathogens will get infected, so they become damaged or may even die. 3.      These abnormal cells will release attractants to bring phagocytes and other white blood cells closer to where the pathogens are located (ie. the site of infection) by a process called chemotaxis. 4.      The phagocytes squeeze through the capillary wall to enter the infected tissue.5.      The phagocytes have several receptors on their cell surface membrane that allows them to bind to chemicals found on the surface of the pathogen. 6.      The phagocyte will then engulf the pathogen into itself forming a ‘phagosome’ – the name given to the vesicle containing the engulfed pathogen 7.      Lysosomes inside the phagocyte will then fuse with the phagosome and release enzymes called ‘lysozymes’ into it. 8.      These lysozymes destroy the engulfed pathogens by hydrolysing their cell walls and breaking down the rest of their contents in a similar fashion to the digestion of food. 9.      The soluble products of this hydrolysis are then absorbed into the cytoplasm of the phagocyte.