Neutrophils

Question 1

what percentage of leucocytes in the blood are neutrophils?

Answer 1

50-70%

Question 2

how do neutrophils use chemotaxis?

Answer 2

neutrophils use chemotaxis to chase around bacteria using the bacteria’s chemical scent

Question 3

Explain the process of Phagocytosis

Answer 3

1. chemotaxis and adherence of microbe to phagocyte
2. Ingestion of microbe by the phagocyte
3. Formation of a phagosome
4. Fusion of the phagosome with a lysosome to form a phagolysosome
5. Digestion of ingested microbe by enzymes
6. Formation of residual body containing indigestible material
7. Waste materials are discharged

Question 4

what are neutrophil extracellular traps (NETs)?

Answer 4

webs of fibres and enzymes that trap and kill microbes extracellularly

Question 5

what are some features of neutrophils?

Answer 5

• 12-14 µm
• circulate in blood for 7-10 hrs
• migrate to tissues and live there for 4-5 days
• very dense
• segmented nucleus with 2-5 lobes
  -granules are difficult to stain so appear neutral

Question 6

what are some functions of neutrophils?

Answer 6

• they are involved in the acute inflammatory response.
• they are first line of defence
• they move to sites of tissue damage/ infection via chemotaxis
  -engulf pathogens using pseudopodia (‘Arms’) into a phagocytic vesicle called a phagosome
• they have lysosomes that bind to the phagosome and release digestive enzymes into it in a process known as degranulation

Question 7

what do Neutrophil extracellular traps (NETs) do and what produces them?

Answer 7

neutrophils produce NETs which trap and kill microbes extracellularly (outside the cell)

Question 8

what happens when neutrophils degenerate?

Answer 8

when neutrophils break down, they release chemicals that attract more neutrophils

Question 9

What is pus mainly made up of?

Answer 9

degenerated neutrophils

Question 10

Why do neutrophils degenerate after enzymes are depleted?

Answer 10

this is because neutrophils have limited capacity to regenerate enzymes that are used up.

Question 11

what might a high count of neutrophils indicate?

Answer 11

• bacterial infection
• burns
• stress
• inflammation

Question 12

what might a low count of neutrophils indicate?

Answer 12

• radiation exposure
• drug toxicity
• vitamin B12 deficiency
• systemic lupus erythematosus (SLE)