Immune System
Immune Systems
- The function of the immune system to differentiated self and non-self cells due to the MHC class markers. it also acts as a defence against pathogenic organisms.
- The immune system is involves organs, tissues, cells and other specific molecules which help to defend the body against pathogens.
- In a healthy body the immune system should be able carry out roles including: identifying between self and non-self, fight against foreign antigens that may harm the body and not destroy non-infected self cells.
Non-Specific Response
Specific Response
Self
Non-Self
Pathogen
Pathogenic Agent
Antigen
Antibody
MHC Markers
- The same response occurs to a pathogen regardless of its type.
Specific Response
- A different response occurs to each pathogen.
Self
- Describes agents that are recognised by the immune system of an organism as being part of that organism.
- All cells have MHC markers on their cell surface which help identify self cells.
Non-Self
- Describes agents that are not recognised by the immune system as being part of the organism its self.
- Non-self cells are classified as foreign and carry markers that identify them as non-self.
Pathogen
- Any organism or agent that is capable of causing an infectious disease in host organism.
Pathogenic Agent
- Any agent that is not an organism and considered living that is capable of causing an infectious disease in an organism.
Antigen
- Any substance or structure that when introduced into the body of an organism stimulates the production of an anti body. Antigen is short for antibody generation.
- There are many sources of antigens, any substance or structure that id foreign to an organism is antigenic. Examples include pathogens such as bacteria and viruses toxins and tissues transplants.
Antibody
- A 'Y' shaped protein secreted by B Cells in response to an antigen. it binds specifically to the antigen that induces production.
MHC Markers
- Major Histocompatability complex.
- The MHC is a group of genes that code for the production of histocompatibility antigens on the external surface of all nucleated cells. These antigens are specific to the individual and identify all self cells.
- Class 1 MHC markers are found on the surface of all nucleated cells (all body cells except red blood cells)
- Class 2 MHC markers are found on the surface of B cells, T cells and macrophages.