3.2.4.2 - Phagocytosis

Question 1

How do phagocytes protect against pathogens, toxins, cancer cells or foreign tissues?

Answer 1

1. The phagocyte is attracted by chemical products of the non-self material.
2. The phagocyte has receptors that bind to the non self antigens of the material.
3. The phagocyte engulfs the material (phagocytosis) and a phagosome is formed.
4. A lysosome merges with the phagosome and lysozymes digest the material.
5. Material debris is absorbed by the phagocyte. Antigens are presented on the surface of the phagocyte.

Question 2

What is phagocytosis?

Answer 2

When foreign material is ingested by a phagocyte to form a phagosome.

Question 3

T-Lymphocytes can be one of 2 types. What are they?

Answer 3

T-helper lymphocytes (T_h)

Cytotoxic T-Lymphocytes (T_c)

Question 4

Identify the 2 types of white blood cell.

Answer 4

Phagocytes (non-specific)

Lymphocytes (specific)

Question 5

What are lysozymes?

Answer 5

Hydrolytic enzymes found inside lysosomes that digest foreign material.

Question 6

What is a phagosome?

Answer 6

A vesicle containing foreign material within a phagocyte that is formed during phagocytosis.

Question 7

Is phagocytosis a specific or a non-specific response to a non-self antigen?

Answer 7

Non-specific

Question 8

Are Phagocytes ‘antigen presenting cells’?

Answer 8

Yes - they present foreign antigens on their surface after engulfing a foreign material.

Question 9

Describe how phagocytosis of a virus leads to presentation of its antigens

Answer 9

Phagosome FUSES with lysosome

lysosome contains lyzozymes which destroy virus]

antigen displayed on cell MEMBRANE of phagocyte (APC)