Flashcards in Unit 3: Neurobiology and immunology - Specific Cellular Defences Against Pathogens Deck (25)
What is specific immune response brought about by?
White blood cells called lymphocytes.
Where are lymphocytes produced?
From stem cells in bone marrow.
What are two types of lymphocytes?
B and T lymphocytes.
What do lymphocytes respond to?
Specific antigens on invading pathogens.
What is an antigen?
A molecule (often a protein) found on the surface of cells.
What are two types of antigens?
Self antigens (belong to the body's own cells) and foreign antigens (do not belong to the body's own cells).
What do foreign antigens do?
Trigger a specific immune response.
What do lymphocytes have in terms of antigens?
Lymphocytes have a single type of antigen receptor which is specific for one antigen.
After foreign antigen binding what does the lymphocyte do?
The lymphocyte divides repeatedly, 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 destruction of a pathogen.
What are antibodies?
Antibodies are Y-shaped proteins with receptor binding sites that are specific to a particular antigen on a pathogen.
Why does an allergic reaction happen?
When B lymphocytes respond to antigens on substances that are harmless to the body e.g. pollen. This hypersensitive response is called an allergic reaction.
Which type of lymphocytes produce antibodies?
What do T lymphocytes do?
T lymphocytes destroy infected body cells by recognising antigens on the pathogen on the cell surface.
How do T lymphocytes destroy infected body cells?
They attach onto the infected cells and release proteins. These proteins diffuse into the infected cells causing the production of self-destructive enzymes which cause cell death.
How are remaining cells of destruction of infected cells by a T lymphocyte removed?
What can T lymphocytes normally distinguish between?
Self antigens on the body's own cells and non-self antigens on infected cells
What does failure of the regulation of the immune system lead to?
T lymphocytes responding to self antigens.
What happens when T lymphocytes respond to self antigens?
T lymphocytes attach the body's own cells causing autoimmune disease such as type 1 diabetes and rheumatoid arthritis.
What do some B and T lymphocytes produced in the response to antigens do?
Survive long term as memory cells.
How do memory cells work?
When the body is exposed to the same antigen for a second time, the memory cells quickly give rise to a new clone of specific lymphocytes, which destroy invading pathogens before an individual shows any symptoms.
How does secondary responses due to memory cells usually prevent diseases?
Antibody production is rapid and more effective than during the primary response.
What does autoimmunity mean?
When the T lymphocytes attack the own body's cells.
Why does someone not experience symptoms if exposed to an antigen for the second time?
The response of antibodies is more rapid an effective.