Immune System

Question 1

What is the role of a neutrophil in a non specific immune response

Answer 1

They carry out phagocytosis (englufment of pathogens)

Question 2

AIDS destroys T lymphocytes, why do AIDS patients suffer from opportunistic infections?

Answer 2

• with fewer T lymphocytes fewer pathogens are killed directly
• the activation of T lymphocytes produces substances to produce T killer cells and b lymphocytes
• this means opportunistic infections have more impact because there are less antibodies to remove the pathogen.

Question 3

What is an immune response

Answer 3

The body’s reaction to a foreign antigen

Question 4

What are antigens

Answer 4

Molecules often glycoproteins on the surface of cells

Question 5

Define phagocytosis

Answer 5

The engulfing and digestion of pathogens

Question 6

What is a phagosome

Answer 6

The vesicle produced when a phagocyte engulfs a pathogen

Question 7

What proteins signal for neutrophils to move towards a wound

Answer 7

Cytokines

Question 8

How does a phagocyte that has captured a pathogen activate a T lymphocyte

Answer 8

The phagocyte engulfs the pathogen and presents its antigens on its surface (antigen presenting cell) the T lymphocyte with the receptor complimentary to the antigen will bind to this and be activated

Question 9

What are the functions of T lymphocytes and plasma cells

Answer 9

• T helper cells release substances which activate B lymphocytes and T killer cells
• T killer cells destroy cells already infected
• Plasma cells produce lots of antibodies

Question 10

What is the role of interleukins in the immune response

Answer 10

T helper cells release interleukins that bind to receptors on B lymphocytes activating them (this is a form of cell signalling)

Question 11

How to anti-toxin antibodies work

Answer 11

• they bind to the toxin, preventing it from affecting human cells and therefore neutralising it
• the toxin can then be phagocytosed

Question 12

What are the function of these regions on the antibody

• variable region
• hinge region
• constant region

Answer 12

• variable region functions to form the antigen binding site
• hinge region provides flexibility when an antigen binds
• constant region allows binding to receptors on immune cells like phagocytes

Question 13

Why is it useful that antibodies have 2 binding sites

Answer 13

So agglutinins can bind to more than one pathogen at a time and clump them together making phagocytosis easier

Question 14

Three ways antibodies defend against pathogens

Answer 14

1- agglutination, sticking pathogens together
2- neutralising toxins
3- preventing them from binding to human cells by blocking their cell surface receptors

Question 15

What is the difference between the primary and secondary immune response

Answer 15

• primary response is slow, secondary is fast due to concentration of memory cells
• primary response still experiences symptoms of the disease
• cells activated in primary response are b and t lymphocytes whereas in secondary response only the memory cells are activated

Question 16

Why is the primary response slower than the secondary

Answer 16

• the primary response is slow because there aren’t many T lymphocytes to bind to the antigen and B lymphocytes to produce antibodies whereas in secondary the memory cells are already in abundance