Unit 3 (K6) - Specific Cellular Defences Against Pathogens Flashcards
What are the two types of lymphocytes?
B and T lymphocytes.
What are antigens?
Antigens are molecules, often proteins, located on the surface of cells that act as a marker to identify “self” cells or invading and diseased cells.
Describe the clonal selection theory?
Antigen binding leads to repeated lymphocyte division resulting in the formation of a clonal population of identical lymphocytes.
How do B lymphocytes bring about the destruction of a pathogen?
B lymphocytes produce antibodies against antigens.
What are is the structure of an antibody?
They are y-shaped structures that have receptor binding sites specific to a particular antigen on a pathogen.
How does an antibody result in the destruction of a pathogen?
Antibodies become bound to antigens, inactivating them. The resulting antigen-antibody complex can then be destroyed by phagocytosis.
What causes an allergic reaction?
B lymphocytes respond to antigens on substances that are harmless to the body e.g. pollen. This hypersensitive response is called an allergic reaction.
What role to cytokines play in immune surveillance?
They increase blood flow resulting in phagocytosis and T cells accumulating at the site of infection.
Describe the destruction of an infected cell by a T lymphocyte?
T lymphocytes destroy infected cells by recognising antigens on the cell membrane of the pathogen and induce apoptosis.
What is meant by the term apoptosis?
Programmed cell death.
How are the remains of a destroyed pathogen removed?
Phagocytosis.
What is autoimmunity?
When T lymphocytes attack the body’s own cells. This can cause diseases such as arthritis and type 1 diabetes.
What are memory cells?
Clonal cells which can survive long-term in the body following the first exposure of a foreign antigen.
What occurs during the secondary response?
Memory cells rapidly give rise to a new clone of specific lymphocytes. They destroy invading pathogens before individual shows symptoms.
During the secondary response how is antibody production different from the first exposure?
The antibody production is greater and more rapid than during the primary response.
