Cells: Cell Recognition & the Immune System - Phagocytosis

Question 1

What is phagocytosis?

Answer 1

• Phagocytosis is the engulfment of pathogens

Question 2

What is a phagocyte?

Answer 2

• A phagocyte is a type of white blood cell that carries out phagocytosis
• Neutrophils and macrophages are examples of phagocytes
• Found in the blood and in tissues
• They’re the first cells to respond to an immune system trigger inside the body

Question 3

Describe the process of phagocytosis

Answer 3

• A phagocyte recognises the foreign antigens on a pathogen
• The cytoplasm of the phagocyte moves round the pathogen, engulfing it
• The pathogen is now contained in a phagocytic vacuole or phagosome, (a bubble) in the cytoplasm of the phagocyte
• A lysosome (an organelle that contains the enzyme lysozyme) fuses with the phagocytic vacuole
• The lysozyme hydrolyses the pathogen
• The phagocytes then present the antigen of the pathogen on its surface to activate other immune system cells
• The phagocyte is acting as an antigen-presenting cell

Question 4

What is an antigen-presenting cell?

Answer 4

• An immune system cell that processes and presents antigens on its surface to activate other immune system cells

Question 5

Is phagocytosis a specific or non-specific response?

Answer 5

• Phagocytosis is a non-specific response
• Its response is immediate
• Its response is the same for all pathogens