Unit 3- Defense Against Pathogens Flashcards
What are antigens?
Protein molecules located on the surface of cells that trigger a specific immune response.
Describe a T lymphocyte.
Destroy infected body cells by recognising their antigens and causing apoptosis (programmed cell death).
Describe a B lymphocyte.
B lymphocytes produce antibodies against antigens leading to the destruction of a pathogen. Antibodies bind to antigens inactivating the pathogen.
Explain how T lymphocytes induce apoptosis.
They attach onto infected cells and release proteins.
Proteins diffuse into infected cells.
Causing the production of self destructive enzymes.
Causing cell death.
How is a clonal population formed?
Antigen binding leads to repeated lymphocyte division resulting in a clonal population of identical lymphocytes.
Describe memory cells.
Cloned B and T lymphocytes which survive long term. A secondary exposure to the same antigen causes memory cells to rapidly give rise to a new clonal population.
What does HIV do?
Attacks and destroys T lymphocytes.
What’s an allergic reaction?
When B lymphocytes respond to antigens on substances that are harmless to the body leading to a hypersensitive reaction.
Describe autoimmunity.
Failure to distinguish between self antigens and non self antigens leads to T lymphocytes responding to self antigens.
Causing T lymphocytes to attack the body’s own cells.
