Specific Immune Response (Basic B Cell + T Cell) Flashcards
What are Lymphocytes?
Lymphocytes: White blood cells that help defend the body against specific diseases.
Where do they circulate?
Circulate the blood and lymph
Where are the reserve supplies of lymphocytes positioned?
Reserve supplies of lymphocytes are held in strategically-positioned in lymphoid tissues.
Example of Lymphocytes in lymphoid tissue
Ear infection: lymphocytes in the lymph nodes of the neck go into action ‘swollen glands’
What are the two main types of Lymphocytes?
Two main types of lymphocytes: B and T Cells
What do B and T cells respond to?
Respond to antigens such as the ones found on the surface of bacteria or viruses.
What are Antigens?
Antigens are protein molecules recognised by the host’s immune system as not being it’s own self.
• Antigens=Protein molecules
• Large numbers
• Characteristic molecular shape
Lymphocytes identify which ones are ‘foreign’ (non-self).
What do B Cells secrete?
B cells: Secrete antibodies in response to antigens.
What are anti-bodies?
Antibodies: Special protein molecules of a class known as immunoglobulin’s.
What do antibodies do? (2)
Antibodies bind to the antigens on the cell surface membrane.
Act as labels, allowing phagocytes to recognise and destroy the cell
What can each B Cell do?
Each B cell only produces one type of antibody, which binds to only one specific antigen.
How many antigens can a microbe have?
A microbe usually has several different types of antigen on it’s surface. Each different antigen will bind and activate different B cells.
Where are B Cells produced?
In the Bone Marrow
How does the Bone Marrow produce B cells and how can this affect a baby?
Each divides rapidly to produce a clone of cells, providing the baby with an immune system that can respond to a variety of antigens that might invade its body after birth.
What do B Cells have on their surface?
B cells have receptors on their surface: these receptors include transmembrane versions of the antibody molecules they produce.
Why is each antibody different?
Amino acid sequence and hence shape of the binding site is different in each type of antibody.
STEPS OF ANTIBODY AND MACROPHAGE
- Bacteria with antigens on surface
- Antibodies bind to antigens and label them
- Antibody binds to the antibody receptor
- Macrophage engulfs antibodies and bacterium
- Lysosomes fuse with vacuole releasing digestive enzymes that destroy the bacterium.
Where are T Cells produced?
Produced in the bone marrow
Where do T Cells mature?
Mature in the thymus gland
What type of antigen receptor do T Cells have?
T cells have one specific type of antigen receptor
What type of antigen do T Cells bind to?
Only binds to an antigen with the complementary shape
Maturing of T Cells Steps (6)
- Immature T Cells are produced by division of stem cells in the bone marrow
- Immature T cells move to the thymus via the blood
- T cells mature in the thymus
- Mature T cells leave the thymus via the blood + move to lymph nodes + spleen
- As lymph fluid passes through the lymph nodes, T cells are activated by any pathogens present
- As blood passes through the spleen, T cells are activated by any pathogens present.
What are the two types of T Cells?
T helper and T killer cells
What are T helper cells?
T helper cells: When activated these stimulate the B cells to divide and become cells capable of producing antibodies. Enhance activity of phagocytes
What are T killer cells?
-T killer cells: Destroy any cells with antigens on their surface membrane that are recognised as ‘foreign’ or ‘non-self’ (Includes tissues in transplant + body cells infected with pathogens)
