Unit 2.5b - Immune response to Parasites

Question 1

What are the two type of first line defences?

Answer 1

Physical Barriers

Chemical Secretion

Question 2

Describe physical barriers to parasite infection

Answer 2

Skin acts as a tough barrier
Skin is dry so many parasites die on surface
Nasal hair trap parasites

Question 3

Describe the role of mucus in preventing parasite infection

Answer 3

Mucus in the lungs trap microbial parasites and are moved away from delicate tissues by cilia

Question 4

How do tears prevent parasites?

Answer 4

Contain antibodies and lysosomes

Question 5

When are second line responses triggered?

Answer 5

After the parasite has entered the body fluid

Question 6

What are the three type of second line defences?

Answer 6

Inflammatory Responses
Phagocytes
Natural Killer Cells

Question 7

Describe an inflammatory response

Answer 7

Some injured cells release chemicals including histamine
Cause local blood vessels to dilate
Increases blood flow to the area
Stimulating phagocytes to migrate to the area

Question 8

What are phagocytes?

Answer 8

White blood cells which are able to migrate from the blood into tissue fluid

Question 9

What do phagocytes do?

Answer 9

Check surface of the particles for self antigens, if not found, phagocyte engulfs and digests the object

Question 10

What do phagocytes do after digestion of non self objects?

Answer 10

Present the fragments of the foreign antigens on the surface

Question 11

What are natural killer cells?

Answer 11

Type of white blood cells which detect abnormal cell surface proteins

Question 12

What do natural killer cells do?

Answer 12

Attach to cells which have abnormal surface proteins and release chemicals into them triggering apoptosis

Question 13

What are specific cellular defences triggered by?

Answer 13

The antigens on the surface of the parasite

Question 14

What are lymphocytes and where are the typically found?

Answer 14

White blood cells mainly found in the lymph gland

Question 15

What are the two types of lymphocytes?

Answer 15

B and T lymphocytes

Question 16

What are the two roles of T lymphocytes?

Answer 16

1. Stimulate other T lymphocytes and cause B lymphocytes to divide rapidly
2. Destroy infected cells

Question 17

What do B lymphocytes do?

Answer 17

Produce antibodies which attach to pathogens allowing phagocytes to engulf and digest them

Question 18

What is it called when some T and B lymphocytes are kept after parasite infection?

Answer 18

Immunological Memory

Question 19

What is clonal selection?

Answer 19

Response of lymphocytes when they bind to their specific antibodies causing rapid replication

Question 20

What is a benefit of immunological memory?

Answer 20

Faster and bigger response to future parasite infection of the same parasite

Question 21

What are the three ways parasites evade the immune system?

Answer 21

1. Mimic the host antigens
2. Antigenic Variation
3. Modify host’s immune system