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The Process of Phagocytosis

The Process of Phagocytosis. Phagocytes is a collective name for a group of white blood cells which increase by two to four amounts of the original number at the site of infection in the human body. Electron Micrograph Of Macrophage Engulfing Bacteria. Macrophage engulfing Bacteria.

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The Process of Phagocytosis

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  1. The Process of Phagocytosis

  2. Phagocytes is a collective name for a group of white blood cells which increase by two to four amounts of the original number at the site of infection in the human body. Electron Micrograph Of Macrophage Engulfing Bacteria

  3. Macrophage engulfing Bacteria The process of Phagocytosis in the immune system involves a eukaryotic cells such as a macrophage or neutrophil (which together are both known as phagocytes) engulfing a solid which can either be a micro-organism or cellular debris, to fight infection.

  4. Phagocytes can be attracted to ‘chemotactic products’. These products act as a stimulus causing the movement of a phagocyte toward them include microbial products, components of damaged cells, chemicals released by other white blood cells and peptides derived by the complement system. The foreign material, or in this case foreign micro-organism attaches to the plasma membrane of the phagocyte. This attachment is called adherence. Adherence often involves interaction between the cell membrane and the glycoproteins of the micro-organism. Adherence can be aided by the process of opsonisation where the micro-organism is coated in a serum made of proteins called opsonins which act as handles for the phagocyte. The phagosome will fuse with a lysosome in the cytoplasm. This structure is now called a phagolysosome. The lysosome which joins the phagosome contains digestive enzymes and digestion of bacteria usually requires 10-30 minutes. After phagocytosis has occurred the phagolysosome fuses with the plasma membrane and releases its contents, which is the remaining debris of the micro-organism. This process is called exocytosis. Some of the debris of the micro-organism may be left on the plasma membrane of the macrophage and act as an antigen presenting cell. Phagocytes have extensions of their cell membrane called pseudopods which move towards micro-organisms and damaged cells at the site of infection. Once the foreign micro-organism has been reached by the pseudopods and drawn to the plasma membrane’s surface, the pseudopods extend around the micro-organism and engulf it into the macrophage. When inside the macrophage the pseudopods join forming a sac around the micro-organism called a phagosome. Micro-organism ‘Non-self’ Pseudopods ‘Self’

  5. Bizone International 1995-2006, defence 7 the Immune System, ‘The Action of Phagocytes’, pg. 110 5/6/2011 http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__phagocytosis.htmlPhagocytosis Animation, 3/6/2011 http://www.sp.uconn.edu/~terry/Common/phago053.htmlPhagocytosis Animation, 3/6/2011 2005 Pearson education Inc. publishing as Benjamin Cunnings, Phagocytosis Animation Nelson Biology VCE UNITS 3 & 4 Anne Semple, Pam Borger, Caroline Cotton, Fiona Cunningham, Jacinta Duncan, Stewart Jackel, pg. 178 3/6/2011 Bibliography

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