Immunity And Antigens Flashcards
What are lymphocytes?
Cells that identify pathogens and harmful foreign substances in the body and then destroy them.
How do lymphocytes distinguish between pathogens and self-cells?
Each type of cell has specific molecules on its surface that identify it.
What are the molecules on the surface of cells?
Antigens.
What do surface molecules allow lymphocytes to identify?
Pathogens, cells from other organisms of the same species, abnormal body cells, and toxins.
Why does the function of a lymphocyte have implications for humans with organ transplants?
The immune system recognises the cells as non-self and attempts to destroy them.
What is used to minimise the effect of lymphocytes on organ transplants?
Donors are matched closely, and immunosuppressant drugs are given to reduce the level of immune response.
How many lymphocytes are in your body?
10 million.
Why do lymphocytes complementary to self-cells die?
To prevent the lymphocytes from attacking those cells, leaving non-self-cell lymphocytes remaining.
What lymphocytes mature in the bone marrow or thymus?
The lymphocytes complementary to non-self cells.
What are autoimmune diseases?
Where lymphocytes complementary to self-cells aren’t destroyed and attack self-cells.
What are antigens?
Molecules, usually proteins, that generate an immune response by lymphocytes when detected in the body.
What happens in antigen variability on a pathogen?
A mutation occurs in a gene that codes for the antigen which changes the shape of the antigen.
What happens to the immunity after antigen variability and why?
Any previous immunity to this pathogen is no longer effective, as all memory cells in the blood have a memory of the old antigen shape.
Why is anew flu vaccine created each year?
The influenza virus mutates and changes its antigens very quickly.
