Specific Cellular Defences Flashcards
What are lymphocytes?
Lymphocytes are white blood cells involved in the specific immune response
Lymphocytes respond to specific antigens on pathogens.
What do lymphocytes respond to?
Specific antigens found on pathogen membranes
What are antigens?
Antigens are molecules, often proteins located on the surface of cells that trigger a specific immune response.
What is meant by ‘lymphocytes are complementary to antigens’?
This means that lymphocytes have a single type of membrane receptor that is specific for one antigen.
What happens when a lymphocyte binds to an antigen?
Antigen binding results in repeated lymphocyte division white causes the formation of a clonal population of identical lymphocytes
What are the two types of lymphocytes?
B lymphocytes and T lymphocytes
What are B lymphocytes?
B lymphocytes are lymphocytes that produce antibodies against antigens, which leads to the specific destruction of the pathogen
What are antibodies?
Antibodies are Y shaped proteins that have a receptor binding site that is specific to a particular antigen on the pathogen.
What do antibodies do once bound to the pathogen?
Antibodies inactivate the pathogen, these antibodies join the inactive pathogens together which results in a antigen-antibody complex which can then be destroyed by phagocytosis.
What happens when B lymphocytes respond to antigens on substances that are harmless?
The B lymphocytes would cause a hypersensitive response by activating mast cells, this would cause a release of histamine which can result in an allergic reaction.
What are T lymphocytes?
T lymphocytes are a type of lymphocyte that destroys infected body cells by recognising antigens of the pathogen on the cell membrane and inducing apoptosis.
What is apoptosis?
Apoptosis is programmed cell death
How do T lymphocytes cause apoptosis?
T lymphocytes attach on to infected cells and release proteins, these proteins diffuse into infected cells causing production of self destructive enzymes which cause cell death.
The remains of the cell are then removed by phagocytosis.
T lymphocytes can normally distinguish between self antigens on the body’s own cells and non self antigens on infected cells.
Just a fact!!
What happens when the immune system isn’t regulated?
T lymphocytes will respond to self antigens, which causes autoimmune diseases.
What happens in autoimmunity?
In autoimmunity, the T lymphocytes attack the body’s own cells. This causes autoimmune diseases such as type 1 diabetes and rheumatoid arthritis.
Give 2 examples of autoimmune diseases.
Rheumatoid arthritis and type 1 diabetes.
What happens on a secondary exposure to the same antigen of a pathogen?
Memory cells will rapidly produce specific lymphocytes that are complementary to the pathogen.
What do memory cells cause?
Memory cells cause the production of specific lymphocytes that destroy the invading pathogens before an individual can show symptoms.
Describe the secondary response in terms of antibody production + concentration
The antibody production is greater and more rapid than the initial response and the concentration of antibodies is greater.
What does human immunodeficiency virus do?
HIV attacks and destroys T lymphocytes, resulting in a depletion of T lymphocytes, leading to the development of AIDS ( acquired immunodeficiency syndrome )
What is typical of individuals with AIDS?
Individuals with AIDS have a weakened immune system and so are more vulnerable to opportunistic infections
