Specific Cellular Defences Against Pathogens Flashcards
What are Lymphocytes?
They are white blood cells involved in the specific immune system
They respond to specific pathogens because they have a single type of membrane receptor which is specific for one antigen on the invading pathogen
What has to happen for a clonal population of identical lymphocytes to form?
The binding of the membrane receptor and the antigen leads to the lymphocyte repeatedly dividing
What are the two types of lymphocytes?
- B Lymphocytes
- T Lymphocytes
What is the function of B Lymphocytes?
They produce antibody’s which bind to antigens inactivating the pathogen
The resulting antibody-antigen complex can them be destroyed by phagocytosis
B lymphocytes can respond to antigens on substances that are harmless to the body resulting in an allergic reaction
What is the function of T Lymphocytes?
They destroy infected body cells by recognising antigens of the pathogen on the membrane and including apoptosis
Apoptosis works by T lymphocytes attaching into affected cells and releasing a protein which diffuses into the cells causing production of self-destructive enzymes. The remains of the cell are then removed by phagocytosis
T-Lymphocytes have specific surface proteins which allow them to do what?
To allow them to distinguish between the surface molecules of own cells and cells with foreign molecules of its surface
- this ability allows T cells to recognise self and non-self, meaning normally there are no lymphocytes acting against the body’s own cells
- immune system regulation failure leads to T-lymphocyte immune response to self-antigens meaning they attach the body’s own cells resulting in auto immune diseases such as type 1 diabetes and rheumatoid arthritis
What is the primary response?
This is when a person is affected by a pathogen or toxin and their body produces antibodies
Some T and B lymphocytes produced in the primary response survive long term as memory cells
What is the secondary response?
These memory cells make a secondary response possible by rapidly giving a rise to a new clone of lymphocytes producing a rapid and greater antibody production meaning the invading pathogen is destroyed before the individual shows symptoms
The human immunodeficiency virus (HIV) does what?
Destroys T lymphocytes causing a depletion of T-lymphocytes. This leads to the development of acquired immune deficiency disease (AIDS) which weakens the immune system making the person more vulnerable to opportunistic infections
