White Blood Cells: Extended (CIE IGCSE Biology: Co-ordinated Sciences (Double Award))
Revision Note
Lymphocytes & Phagocytes: Extended
Extended Tier Only
- White blood cells are part of the body’s immune system, defending against infection by pathogenic microorganisms
- There are two main types, phagocytes and lymphocytes
Phagocytes
- Carry out phagocytosis by engulfing and digesting pathogens
Phagocytosis
- Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells
- Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it
- They can be easily recognised under the microscope by their multi-lobed nucleus and their granular cytoplasm
Lymphocytes
- Produce antibodies to destroy pathogenic cells and antitoxins to neutralise toxins released by pathogens
- They can easily be recognised under the microscope by their large round nucleus which takes up nearly the whole cell and their clear, non-granular cytoplasm
Lymphocytes and phagocytes can be identified on a micrograph image
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