Specific defences Flashcards
What is released upon damage
Cytokines
Name the two types of lymphocytes
B and T
What do lymphocytes respond to
Specific antigens on invading pathogens
What are antigens
Molecules (often proteins) found on the surface of cells. They act as a marker for ‘self’ calls or invading/diseased cells.
What is triggered when lymphocytes bind to antigens
Specific immune response
What is clinal selection theory
Lymphocytes have a single type of membrane receptor which is specific to one antigen. Antigen binding leads to repeated lymphocyte division resulting in the formation of a clinal population of identical lymphocytes.
What do B lymphocytes produce
Antibodies
What are Antibodies
Y-Shaped proteins that have receptor binding sites specific to a particular antigen on a pathogen.
What do antibodies do
Bind to antigens and inactivate the patjogen. The resulting antigen-antibody complex is then destroyed by phagocytosis
What is an allergic reaction
When B lymphocytes respond to antigens on harmless substances and issue a hypersensitive response
How do T-Lymphocytes work
They recognise antigens of the pathogen on the cells membrane and induce apoptosis
What is apoptosis
Programmed cell death
Describe apoptosis
T lymphocytes attach onto infected cells and release proteins. These proteins diffuse into the infected cells and cause production of self-destructive enzymes which cause cell death. The remains are then removed by phagocytosis
AWhat cause autoimmune disease
Failure of the regulation of the immune system leads to T lymphocytes responding to self antigens. In autoimmunity, the T lymphocytes attack the body’s own cells
Give two examples of autoimmune disease
Rheumatoid arthritis and type one diabetes
What are memory cells
Cells produced by clinal selection that survive long term in the body
Describe the secondary response
When secondary exposure to the same antigen occurs, memory cells rapidly give rise to a new clone of specific lymphocytes. These destroy the pathogens before the individual shows symptoms
What does HIV stand for and what does it do
Human immunodeficiency virus attacks and destroys T lymphocytes
What does HIV lead to
HIV causes depletion of T lymphocytes which leads to the development of AIDS
What does AIDS stand for and what does it entail
Aquired immune deficiency syndrome. Individuals with aids have a weakened immune system and so are more vulnerable to opportunistic infections
