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, it moves towards the pathogen along a concerntration gradient.
2. The phagocyte has receptors that bind to the non self antigens of the material.
3. The phagocyte engulfs the material (phagocytosis) and a vesicle known as a phagosome is formed.
4. lysosomes within the phagocyte migrate towards the phagosome and fuse with it.
5. lysosomes contain hydrolytic enzymes called lyzozymes which hydrolyse the cell walls of the ingested bacteria and destroy it (material digested).
6. Soluble products absorbed by cytoplasm. 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)

Question 10

why are lysozymes found in tears?

Answer 10

they protect our eyes from bacterial invaders.