General Information
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- The function of the immune system is to distinguish between self and non-self cells; It is because of the MHC class markers that our cells are able to identify self and non-self cells)
- It also acts as a defense mechanism against pathogenic organisms.
- The immune system is made up of a network of cells (some specialised), organs, tissues and specific molecules that work together to defend the body against invading micro organisms
- The immune system is usually able to provide us with immunity by the body having chemical and physical barriers and cellular defenses to prevent pathogens from entering our body and spreading
- There are 3 line of defenses the body uses when fighting against the invading pathogen. The first two being non-specific and the third and final line of defense being specific.
- A "major player" of the immune system is the lymphatic system as it facilitates the immune system
- White blood cells are vital to the immune system as they detect the first signs of foreign material (invading pathogens) . There are various types (leucocytes) that have specific roles to play in the 2nd and 3rd line of defense
Self vs non-self
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- Self : Cells that are deemed as belonging to the organism and therefore able to co-exist with the immune system and other cells in the body without being attacked. -
- They bind to peptide fragments of the pathogens and display them on the cell surface to alert T-cells of the infection
- MHC markers are determined by the genetic makeup of and individual so they are therefore unique to the individual.
There are two types of MHC class maker molecules:
~Class I: Found on all body cells that have a nucleus. It signals that the cell has been infected and it needs to be destroyed.
~Class II: Only found on B and T-lymphocytes and some macrophages. It activates intra-cellular pathways generally leading to apoptosis
- Non-self: Agents that aren't recognised by the immune system and are identified as being 'foreign' to the body due to their MHC class marker moleculers differing from those of cells that are deemed as belonging to 'self'.