Phagocytosis

Question 1

What are the body’s first and second line of defence?

Answer 1

1st line of defence: physical/chemical barrier
If this fails…
2nd line of defence: white blood cells

Question 2

Name the two types of white blood cell

Answer 2

Lymphocytes and phagocytes

Question 3

What is the difference between a phagocyte and a lymphocyte?

Answer 3

Phagocytes: ingest + destroy the pathogen through phagocytosis before it can cause harm
Lymphocytes: involved in immune responses

Question 4

What attracts phagocytes?

Answer 4

Chemical products of pathogens or dead, damaged and abnormal cells (phagocytes move towards the pathogen)

Question 5

What do phagocytes have on their cell-surface membrane and what do they do?

Answer 5

They have several receptors on the cell-surface membrane.

They recognise and attach to chemicals on the surface of the pathogen

Question 6

What do phagocytes do to the pathogen and what forms?

Answer 6

They engulf the pathogen to form a vesicle which is known as a phagosome

Question 7

What do the lysosomes do to the phagosome?

Answer 7

They move towards the vesicle and fuse with it

Question 8

What do the lysozymes do to the pathogen?

Answer 8

They destroy ingested bacteria by hydrolysis of their cell walls. (The process is the same as digestion of food in intestines - hydrolysis of larger, insoluble molecules into smaller, soluble ones)

Question 9

What happens to the soluble products?

Answer 9

The soluble products from the breakdown of the pathogen are absorbed into the cytoplasm of the phagocyte