Second Line of Defence - Phagocytosis

Question 1

What are phagocytes?

Answer 1

Leukocytes that engulf pathogens and break them down

Question 2

State the 3 types of Phagocytes

Answer 2

• Neutrophils
• Macrophages
• Dendritic Cells

Question 3

What is a vesicle?

Answer 3

A bubble

Question 4

Explain first stage of Phagocytosis

Answer 4

PAMP on pathogen binds to TLR on phagocyte. Pseudopodia extend around the pathogen until it is enclosed in vesicle called phagosome

Question 5

What are pseudopodia?

Answer 5

Arm like things of phagoctes that help surround and engulf pathogen

Question 6

Explain second stage of phagocytosis

Enzymes

Answer 6

vesicle containing enzymes fuze with phagosomes producing a phagolysosome. The enzymes break down the pathogen.

Question 7

Explain third stage of phagocytosis

Digestion

Answer 7

The digested parts of pathogen are mainly recycled by the cell. The pathogen is destroyed.

Question 8

What is special about Neutrophils?

Answer 8

• Neutrophils are the fastest phagocyte
• Neutrophils destroy themself after engulfing several pathogens

Question 9

Which cells are Antigen Presenting Cells

Answer 9

Macrophages and Dendritic Cells

Question 10

What are antigen presenting cells?

Answer 10

Display/present fragment of pathogen protein on Major Histocompatibility Protein Type II (MHC-2)