cells and the immune system Flashcards
define the term antigen
molecules that generate an immune response (usually a protein)
name four main stages of the immune response
phagocytosis, Tcell activation, Bcell activation, plasma cell and antibody production
how are t cells activated
receptors on Tcells bind to complementary antigens presented bu antigen presenting cells
How do phagocytes become antigen presenting cells?
Phagocytes recognise the foreign antigen on a pathogen
Cytoplasm changes shape to engulf the pathogen to form a phagocytic vesicle
Lysosomes fuse with the vacuole and release lysozymes to digest the pathogen
Antigens from the digested pathogen then get inserted into the phagocyte’s cell surface membrane
What happens to a T-cell when it is activated?
Activated T-cells divide rapidly by mitosis and differentiate into T helper cells, T killer cells (cytotoxic T cells), and T memory cells
How are antibodies produced?
Specific B-cells bind to the antigen by their complementary cell surface antibody
Helper T-cells attach the B-cell via the bound antigen
This activates the B cell to divide by mitosis
The clones differentiate into either plasma cells which release monoclonal antibodies specific to the antigen or B memory cells.
Describe the roles of antibodies
Bind to antigens to form an antigen-antibody complex
Agglutination – clumping together of pathogens
Serve as markers to stimulate phagocytes to engulf pathogens to which they are bound
What is the difference between cellular immune response and humoral response
cellular immune response: T cells and other immune system cells that they interact with
humoral response: B cells, clonal selection and production of monoclonal antbodies
difference between active and passive immunity
Active immunity is when the immune system is stimulated to produce antibodies specific to an antigen.
Passive immunity is when antibodies are introduced from an outside source.
What does vaccination / immunisation involve?
The introduction of an antigen into the body to induce an immune response and produce memory cells, which can remain in the blood long term and allow an immediate response to a future infection.
What is herd immunity?
Herd immunity arises when a sufficiently large proportion of the population has been vaccinated to make it difficult for a pathogen to spread within the population.
What is antigenic variation?
When pathogens change their surface antigens.
What are monoclonal antibodies?
Identical antibodies produced form a single group of plasma cells.
How can monoclonal antibodies be used to target specific cell types (e.g. cancer cells)?
Monoclonal antibodies with anti-cancer drugs attached can be made that will bind to tumour markers, meaning that the drug will only accumulate in the boy where there are cancer cells.
What is ELISA testing?
ELISA testing uses antibodies with an enzyme attached, which can react with a substrate to produce a coloured product, demonstrating the presence of a specific protein /antigen.
