Lesson 47 - The specific immune response

Question 1

What is the difference between a specific and non-specific immunity?

Answer 1

Specific immune response is a slower response but specific to each pathogen and can provide long-term immunity. Consist of the cell mediated response and the humoral response.

Question 2

How are lymphocytes made?

Answer 2

They develop from stem cells (undifferentiated cells) in the bone marrow.
B lymphocytes - mature in the bone marrow
T lymphocytes - mature in the thymus gland

Question 3

What is the role of T cells in the immune response?

Answer 3

They’re a type of white blood cell which have receptor proteins on their surface that bind to complementary antigens presented to it by phagocytes, which activates the T-cell.
Helper T-cells: Release chemical signals that activate and stimulate phagocytes and cytotoxic T-cells.
Cytotoxic T-cells: Kill abnormal and foreign cells.
B-cells: Secrete antibodies.

Question 4

What is the role of B cells in the immune response?

Answer 4

• They’re also a type of white blood cell. They’re covered with antibodies, proteins that bind to antigens, to form an antigen-antibody complex.
• (Each B-cell has a different shaped antibody on it’s membrane, so different ones bind to different shaped antigens.)
• This, together with substances released from helper T-cells, activates the B-cell. This process is called clonal selection.
• The activated B-cells divide into plasma cells by mitosis.

Question 5

What happens during ‘antibody production’ in the immune response?

Answer 5

• Plasma cells are identical to the B-cell (clones) they secrete loads of antibodies specific to the antigen, called monoclonal antibodies
• They bind to the antigens on the surface of the pathogen to form lots of antigen-antibody complexes.
• An antibody has 2 binding sites so can bind to 2 pathogens at the same time. Leading to agglutination. Phagocytes then bind to the antibodies and then phagocytose many pathogens at once.

Question 6

What are the cellular and humoral responses?

Answer 6

Cellular: The T-cells, phagocytes and other immune system cells.
Humoral: B-cells, clonal selection and the production of monoclonal antibodies

The responses react with each other, e.g. T-cells activate B-cells, and antibodies coat pathogens making it easier for phagocytes to engulf them.

Question 7

What is the primary immune response?

Answer 7

When an antigen enters the body for the first time, activating the immune system.
- It’s slow, as there aren’t many B-cells that can make the antibody needed to bind to it.
- Eventually the body will produce enough of the right antibody to overcome the infection, meanwhile the infected person will show symptoms of the disease.
- T-cells and B-cells will produce memory cells.

Question 8

What is the secondary immune response?

Answer 8

The same pathogen enters the body again, the immune system will produce a quicker, stronger immune response.
- Clonal selection happens faster. Memory B-cells are activated and divide into plasma cells that produce the right antibody to the antigen.
- Memory T-cells are activated and divide into the correct type of T-cell to kill the cell carrying the antigen.
- The pathogens are often removed before you show any symptoms.