Specific Cellular Defence Against Pathogens Flashcards
Name some features of an antigen?
- Antigens are proteins found on the surface of all living cells.
- They are specific to the cell which they belong to.
- Trigger specific immune responses in the body.
Which cells of the body are responsible for the specific immune response?
lymphocytes (type of white blood cell)
Why are lymphocytes described as specific?
lymphocytes each have a single type of membrane receptor which is specific for one antigen.
What is clonal population?
The many copies of a specific lymphocyte
What will happen to the lymphocytes generated in the clonal population?
Most will fight the infection but some will remain in the blood for years as “memory cells”
What are the two types of lymphocytes?
- B lymphocytes
- T lymphocytes
What do B lymphocytes in response to an invading pathogen?
These cells release huge quantities of antibodies in response to a specific antigenic marker on a pathogen.
What are antibodies and how do they work?
Y- shaped Proteins with receptor binding sites specific to 1 type of antigen. They recognise then bind to antigens, inactivating the pathogen.
What is an antigen-antibody complex? How is this eventually removed from the body?
This is when the antibodies are fixed onto the antigens of pathogens (making them inactive).
It is eventually removed from the body by phagocytes in which they are engulfed and digested.
What is an allergy?
When B lymphocytes respond to antigens that are harmless to the body. This is a hypersensitive response that is commonly called an allergic reaction.
What do T lymphocytes do?
T lymphocytes destroy infected body tissues.
How do they detect infected cells/tissues?
They recognise foreign antigens which have been displaced onto the membrane of cells that pathogens have infected.
What happens to the remains of the cell once destroyed?
Engulfed and digested by a phagocyte – non-specific.
What is the difference between a self-antigen and a non-self-antigen?
Self Antigen - Antigens typically found on the surface membranes of the body’s own cells.
Non Self Antigen - Antigens from pathogens present on infected body cells.
What causes autoimmunity?
When T lymphocytes are unable to distinguish between self and non-self antigens causing them to attack the body’s own cells. This results in auto immune diseases.
