Specific cellular defences against pathogens Flashcards
What are lymphocytes?
They are white blood cells involved in the specific immune response.
What are the two types of lymphocytes?
- B lymphocytes
- T lymphocytes
How do lymphocytes bind to antigens and what is the impact of this?
Lymphocytes have a single type of membrane receptor which is specific for one antigen. Antigen binding leads to repeated lymphocyte division resulting in the formation of a clonal population of identical lymphocytes.
What do B lymphocytes do?
They produce antibodies against antigens, and this leads to the destruction of the pathogen.
What are antibodies?
They are Y shaped proteins that have a receptor binding sites specific to a particular antigen or pathogen. The antibodies become bound to antigens, inactivating the pathogen. The resulting antigen - antibody complex can then be destroyed by phagocytosis.
What is a ‘hypersensitive response’ by B lymphocytes?
B-lymphocytes can respond to antigens on substances which are harmless to the body. e.g. pollen
This is called an allergic reaction
What is apoptosis?
Programmed cell death
How do T lymphocytes destroy infected cells?
T-lymphocytes destroy infected body cells by recognising antigens of the pathogen on cell membrane and inducing apoptosis. They attach onto infected cells and release proteins. These proteins diffuse into infected cells causing the production of self-destructive enzymes which cause cell death. The remains of the cell are then removed by phagocytosis.
What is the consequence of T-lymphocytes failing to regulate?
Failure of regulation on the immune system leads to T-lymphocytes responding to self-antigens. This causes autoimmune diseases.
What happens in autoimmunity?
The T-lymphocytes attack the body’s own cells.
Name two diseases that autoimmunity can cause:
- Type 1 diabetes
- Rheumatoid arthritis
What does the development of memory cells provide?
Immunity
When does a memory cell give rise to a new clone of a specific lymphocyte?
When a secondary exposure to the same antigen occurs.
What is the purpose of memory cells?
To destroy invading pathogens before the individual shows any symptoms.
How does the HIV virus cause AIDS?
HIV virus attacks and destroys T lymphocytes. It cause a depletion of T lymphocytes which leads to the development of acquired immune deficiency syndrome (AIDS).
