What is the immune system
The bodies defence system against pathogens that includes specific and non specific responses
What is a pathogen
A microorganism that causes disease
What is an antigen
A protien on surface of pathogen or cell that triggers an immune response
What are the main stages of the specific immune response
. Phagocytosis
. Activation of T cells
. Activation of B cells and antibody production
. Production of memory cells
What is phagocytosis
A non specific immune response where phagocytes engulf and destroy pathogens
Describe the process of phagocytosis
. Phagocyte recognises foreign antigens
. It moves to it and engulf it
. Phagosome forms around the pathogen
. Lysozomes fuse with the phagosome and release lysozymes that digest the pathogen
. The antigens of the pathogen are presented on the surface of the cell, turning the phahocyte into an antigen presenting cell
What are antigen Prestenting cells
Cells that display antigens on there surface to activate T cells
What are T cells
White blood cells that are activated by antigen presenting cells. They include:
. helper T cells (Th cells): release chemicals to activate B cells and phagocytes
. Cytotoxic cells (Ch cells): kills infected cells
What are B cells
White blood cells that at3 activated by Th cells. They devide into plasma cells and memory cells
What do plasma cells do
They secrete large amounts of specific antibodies against the pathogens antigen
What is an antibody
A protien produces by B cells that binds specifically to antigens, forming antibody complexes
How do antibodies help destroy pathogens
. Aglutination: clumps pathogens together
. Neutralisation: prevents pathogens entry into cells
. Enhances phagocytosis
What are memory cells
Long lived cells that remain in the body and respond quickly id the same pathogen infects again (secondary immune response)
What is the difference between primary and secondary immune response
. Primary response: slower, lower concentration of antibodies
. Secondary response: faster, stronger due to memory cells
What is the difference between cellular and humoral responses
Cellular resonse: involves T cells targeting infected cells
Humoral response: involves B cells and antibody production
What is active immunity
Immunity from the body producing its own antibodies (e.g. after infection or vaccination)
What is passive immunity
Immunity from receiving antibodies from another source (e.g. during pregnancy or injection)
How do vaccines work
Dead organisms weekend form of the pathogen is injected into the body that stimulate the immune system to produce antibodies without causing disease
What is antigenetic variation and why is it an issue
When pathogens change their surface antigens (e.g. flue virus) making it harder for memory cells to recognise them, so vaccine needs to be updated
What is the role of monoclonal antibodies in medicine
These are antibodies that are all come from the same clone of a single hybridoma cell. They are used in targeting drugs, cancer therapy and diagnostic tests (e.g. pregnancy tests)
What is an antibody
A protien produced by B cells that binds specifically to antigens to help destroy pathogens
What is the structure of an antibody
Y-shaped with 2 variable regions for antigen binding and a constant region
What makes an antibody specific
Each antibody has a specific shape to fit a specific antigen
What is a monoclonal antibody
Identical antibodies that all are produced from the the same single hybridoma cell
