Immune System LO

Question 1

Describe the importance of non-specific immunity to include natural barriers and inflammation

Answer 1

Mechanisms that protect the body against a wide range of dangers
Usually present from birth
Sometimes termed innate
1) epithelial barriers - nose hair, cilia
2) microbial substances - saliva, lysosome, antibodies, interferons
3) phagocytosis
4) inflammatory - increased blood flow + build up of tissue fluid
5) immunological surveillance - natural killer cells

Question 2

Describe the importance of specific immunity

Answer 2

• targeted to one antigen
• a memory is created with each immune-response, so if it is encountered again, the response is faster and more powerful
• doesn’t attack its own cells

Question 3

Examples of specific immunity

Answer 3

1) lymphocytes
2) T-cells
3) B-cells

Question 4

Define the term antibody

Answer 4

A blood protein produced in response to interacting with a specific antigen.
Antibodies combine chemically with substances which the body recognises as alien, such as bacteria, viruses, and foreign substances in the blood.

Question 5

Define the term antigen

Answer 5

A toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.

Question 6

Describe humeral immunity

Answer 6

• B cells recognise and bind to antigen particles directly
• B cells make antibodies
• some antibodies released into bloodstream for distribution around the body
• B cell also displays antibody on on its cell
• membrane bound antibodies act as antigen receptor
• helper T cells enable B cell to enlarge and proliferate, making 2 distinct types of B cell: memory B cells and plasma cells
• memory B cells: provide long term immunity for that antigen
• plasma cells: produce antibodies that bind to, and destroy the antigen

Question 7

Describe cell mediated immunity

Answer 7

• after maturation in the thymus gland T cells released into circulation
• cannot detect free antigens
• after digesting the antigen they transport the antigenetic fragment to their own cell membrane and display it on their surface

Question 8

Outline active immunity

Answer 8

The individual has responded to an antigen and produced their own antibodies, lymphocytes are activated and the memory cells formed provide long lasting resistance

Question 9

Outline passive immunity

Answer 9

The individual is given antibodies produced by someone else. The antibodies break down with time so passive immunity is relatively brief

Question 10

Define natural immunity

Answer 10

The body may be stimulated to produce its own antibodies by either having the disease or having a sub clinical infection. Acquired before birth by the passage of maternal antibodies across the placenta to the foetus and to the baby in breast milk

Question 11

Define artificial immunity

Answer 11

In response to the administration of dead or live artificially weakened pathogens or deactivated toxins. Ready-made antibodies, in human or animal serum are injected into the recipient

Question 12

Outline the role of the lymphatic system in immunity

Answer 12

• maintains fluid balance by returning tissue fluid into venous blood stream
• contains lymphoid structures containing lymphocytes e.g. tonsils, spleen, bone marrow
• lymph nodes filter fluid as it passes through
• organic material destroyed via phagocytosis in lymph nodes
• fluid may pass through several lymph nodes before being filtered
• cancers may travel to other parts of the body via lymphatic system