Unit Three - Key Area 6 Flashcards
What are lymphocytes?
Lymphocytes are white blood cells involved in the specific immune response.
What are the two types of lymphocytes?
B lymphocytes and T lymphocytes
How do lymphocytes bind to antigens and what is the impact?
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?
B lymphocytes produce antibodies against antigens, and this leads to the destruction of the pathogen.
What are antibodies?
Antibodies are Y-shaped proteins that have receptor binding sites specific to a particular antigen or pathogen. Antibodies become bound to antigens, inactivating the pathogen.
The resulting antigen-antibody complex can then be destroyed by phagocytosis.
What is the hypersensitive response and what is it called?
B-lymphocytes can respond to antigens on substances which are harmless to the body, e.g. Pollen. This hypersensitive response 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. T lymphocytes 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 are the consequences of T-lymphocytes failing to regulate?
T-lymphocytes can normally distinguish between self-antigens on the body’s own cells and non-self-antigens on infected cells.
Failure of regulation of the immune system leads to T lymphocytes responding to self-antigens. This causes autoimmune diseases.
What happens in autoimmunity and what does this cause?
The T-lymphocytes attack the body’s own cells. This causes autoimmune diseases such as type 1 diabetes and rheumatoid arthritis.
What does the development of memory cells provide and describe how this works?
Immunity - when a secondary exposure to the same antigen occurs, these memory cells rapidly give rise to a new clone of specific lymphocytes. These destroy invading pathogens before an individual starts to show any symptoms.
What does HIV do and cause?
Human immunodeficiency virus attacks and destroys T lymphocytes. HIV causes depletion of T lymphocytes which leads to the development of acquired immune deficiency syndrome or AIDS.
What can a weakened immune system mean?
individuals are more vulnerable to opportunistic infections, such as pneumonia and influenza.
