Immunology Flashcards
What is the definition of an antibody?
A protein produced by a B lymphocyte/ B plasma cell in response to the presence of a non-self antigen
What is the definition of an antigen?
A molecule, usually a protein, that triggers an immune response
What does immunity mean
The ability to resist invading pathogens
What is the process called whereby a type of white blood cell engulfs and destroys a pathogenic microorganism?
Phagocytosis
What is a phagosome?
The vesicle formed when a phagocyte engulfs a pathogenic microorganism
What does a lysosome contain?
Lysozyme and other hydrolytic enzymes to digest/ break down the pathogenic microbe
What are the roles of T helper cells and cytotoxic T cells in the cellular response?
-T helper cells bind with the antigens on the surface of antigen-presenting cells and then stimulate other T cells to divide to form a clone.
- cytotoxic T cells kill infected cells by making holes in their cell-surface membranes
What are the two types of B lymphocytes involved in the humoral response? Briefly explain their function.
Plasma cells- produce antibodies ; short-lived; the main role in primary immune response
Memory cells- long-lived; respond to re-exposure to specific antigens when they divide rapidly to form plasma cells and more memory cells, have main role in secondary response
Describe the difference in the primary immune response and the secondary immune response in terms of :(a) response time (b) antibody levels (c) longevity of response
Primary immune response - slow to respond , low levels of antibodies produces, relatively short lived
Secondary immune response- very rapid response, high levels of antibodies produced , long lived
What is antigenic Variability ?
Variation in the shape and structure of the antigens on the pathogen, caused by genetic variation
Describe the shape of an antibody molecule ?
- protein made up of 4 polypeptide chains
- two heavy and two light
- the chains are arranged to make a y shape
- held together by disulphide bridge
- the fork of the y acts as a hinge
- the structure of all antibodies are identical apart from the variable regions at the top of the y
What is a mono colonal antibody ?
A single type of antibody that has been isolated and cloned , usually in mice
List the uses of monoclonal antibodies
- used in ELISA tests to diagnose some disease
- to detect drugs in urine
- in pregnancy tests
-to deliver drugs to specific cells
Describe the difference between active immunity and active immunity?
- active immunity happens when the immune system is stimulated to produce antibodies ; it is generally long lasting
- passive immunity happens when antibodies are given to an individual; it is short lived as the antibodies are broken down by the body and not replaced
Define vaccination
The introduction of an antigen into the body to stimulate an active immune response against a specific pathogen
