6.3 T Cells and Cell-Mediated Immunity Flashcards
- What are antigens? - What are the two maine types of lymphocyte? - What is the role of T cells in cell-mediated immunity?
What is an antigen?
Any part of an organism or substance that is recognised as foreign by the immune system and stimulates an immune response.
What does the presence of an antigen trigger?
The production of an antibody as part of the body’s defence system.
What are the two types of lymphocyte?
B Cells
T Cells
Where are both of these cells formed?
Bone marrow
What are T Cells?
They are involved with cell-mediated response.
What indiciates where each cell developed & matured?
Their name
Where did B cells develop and mature?
B = Bone marrow
Where did T cells develop and mature?
T = Thymus gland
What do T cells do?
Respond to an organism’s own cells that have been invaded by non-self material e.g. virus
What are the three ways T cells distinguish between invader cells from normal cells?
Phagocytes present some of the pathogen’s antigens on their own cell-surface membrane.
Body cells invaded by a virus present the viral antigens on their cell-surface membrane as a sign of distress.
Cancer cells present antigens on their cell-surface membranes.
What are the cells that present antigens on their cell surface called?
Antigen-presenting cells
Why is it called cell-mediated immunity?
Because T cells only respond to antigens that are attached to body cells, no cells within the fluids.
What is the first stage in the response of T cells to infection by a pathogen?
The phagocyte places antigens from the pathogen on its cell-surface membrane.
What is the second stage in the response of T cells to infection by a pathogen?
Receptors on certain T helper cells fit exactly onto these antigens.
What is the third stage in the response of T cells to infection by a pathogen?
T cells are activated to divide rapidly by mitosis and form a clone.
