U3 KA6 - Specific Cellular Defences

Question 1

What are Lymphocytes?

Answer 1

White blood cells involved in the specific immune response​

Question 2

What are the two types of Lymphocytes?

Answer 2

B Lymphocytes and T Lymphocytes

Question 3

What is the role of B Lymphocytes?

Answer 3

To produce specific antibodies against antigens, which leads to the destruction of the pathogen.​

Each B-lymphocyte clone produces a specific antibody molecule that will recognise a specific antigen surface molecule of a pathogen.

Question 4

What are Antibodies?

Answer 4

Y-shaped protein molecules which have binding sites specific to particular antigens. When antibodies bind to antigens, the pathogen is inactivated.​

Question 5

What is an Antigen?

Answer 5

Antigens are molecules, also often proteins, located on the surface of foreign cells (e.g. pathogens) that trigger the specific immune response.​

Antigens are specific to each invading pathogen therefore lymphocytes will produce a specific antibody to combat the invasion

Question 6

What is Clonal Selection Theory?

Answer 6

Once the lymphocyte has been selected for a specific antigen, it multiplies, creating large numbers of identical lymphocytes (clones) bearing that particular receptor.

Question 7

What does the binding of an antibody to an antigen do?

Answer 7

It creates an antibody-antigen complex.​

The formation of this complex inactivates the pathogen (or its toxin), making it more susceptible to phagocytosis. ​

The antigen-antibody complex can then be destroyed by phagocytosis ​

Sometimes, the antibody-antigen complex stimulates the activation of proteins that bring about lysis (bursting) of the pathogen.

Question 8

Describe Allergies in terms of the immune system

Answer 8

B lymphocytes can trigger an immune response against substances that are harmless to the body, for example, pollen, a normally harmless antigen. ​

An allergy is a normally harmless hypersensitivity by B lymphocytes to an antigen.

Question 9

What is the role of T lymphocytes?

Answer 9

To destroy body cells that have been infected by the pathogen

Question 10

What is apoptosis?

Answer 10

Programmed cell death

Question 11

Describe the process of Apoptosis

Answer 11

1. Cell becomes infected with pathogen (virus)
2. T Lymphocytes attach onto antigen of infected cells and release proteins.
3. These proteins diffuse into infected cells causing production of self-destructive enzymes – it is these enzymes which cause cell death (apoptosis).
4. The remains of the cells are then removed by phagocytosis

Question 12

What happens If the immune system fails to recognise the difference between self and non-self-antigens?

Answer 12

It can result in T lymphocytes attacking the body’s own cells. This can lead to autoimmune diseases.​

Question 13

Examples of autoimmune diseases

Answer 13

• type 1 diabetes
• rheumatoid arthritis
• multiple sclerosis ​

Question 14

Whats the difference between the primary immune response and the secondary immune response?

Answer 14

The Secondary immune response is much more rapid because:

• Antibody production is much more rapid ​
• Concentration of antibodies produced reaches a much higher level (greater)​

-The higher concentration of antibodies is maintained for a longer time

Question 15

What makes the secondary immune response possible?

Answer 15

memory cells

Question 16

What are memory cells?

Answer 16

These are B and T lymphocytes specific to the antigen which are made in response to clonal selection following first exposure.

When a person is exposed to the same pathogen for a second time, these cells multiply rapidly to produce clones of that lymphocyte to attack and destroy the pathogen before the individual exhibits symptoms.

Question 17

What is HIV

Answer 17

Human Immunodeficiency Virus (HIV) is a virus that attacks and destroys the body’s T lymphocytes.

Question 18

What impact does HIV have on the immune system?

Answer 18

The reduction in the number of T lymphocytes in the body due to HIV can then lead to the development of Acquired Immune Deficiency Syndrome (AIDS).

Question 19

What is AIDS

Answer 19

Acquired Immune Deficiency Syndrome (AIDS).​

Individuals with AIDS have a weakened immune system and so are more vulnerable to attack from other infections.​

Without immunity, infection by microorganisms, such as those that cause tuberculosis and pneumonia, becomes more common, and can be fatal.​

Question 20

What is the Treatment for HIV/AIDS

Answer 20

These is no cure for HIV/AIDS therefore they are given antiretroviral drugs.

Antiretroviral drugs work by stopping the virus replicating in the body. This allows the immune system to repair itself and prevents the development of AIDS. This treatment is highly effective and allows people infected with HIV to live long and otherwise healthy life.​

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