6.3.2 - Antigen presentation Flashcards
Describe the in depth process of phagocytosis.
1) Phagocyte attracted to the pathogen by chemical products.
2) Phagocyte receptors attach to the pathogen, envelopes and engulfs the pathogen
3) Membrane folds inwards
4) Pathogen is trapped inside a vacuole called the phagosome
5) Lysosomes fuse with the phagosome forming a phagolysosome, lysosomes release enzymes such as lysins or lysozymes
7) Lysozyme enzymes digest the pathogen
8) Nutrients can be absorbed or exoxytosed into extracellular fluif
What does the non-specific immune system do?
Aims to stop any pathogens getting in regardless.
E.g skin, neutrophils and macrophages
What is the specific immune system?
It’s specific to certain pathogens.
Each T and B cell tailored towards a specific pathogen
What is an MHC molecule?
MHC is a molecule found on the cell surface membrane of all cells and is used to present antigens, both self and non-self
What do phagocytes do after they digest a pathogen?
They present parts of the pathogen (antigens) on their surface attached to MHC molecules
What do the receptors on helper T cells do?
They are attracted to the antigen attahced to the MHC on the surface of a phagocyte.
They then bind to this
How do helper T cells become activated?
Attaching to an antigen presented via the receptors
What do T helper cells do when they become activated?
Release cytokines
What do cytokines do?
Stimulate other Leukocytes
Other than releasing cytokines what else to activated T helper cells do?
Divide by mitosis, creating many more identical copies
Where are helper T cells made and where do they mature?
Made in bone marrow
Mature in thymus gland
What is the humoral response?
The immune response to pathogens free in the tissues and blood stream- involves antibodies
What is the cell- medicated response?
the response to your own body cells that have altered self-antigen.
I.e. cells that have become infected by viruses, or cells that have become cancerous.
What are killer T cells?
Killer T-cells can attack body cells which have been antigenically altered by viruses or cancer cells.
They destroy the pathogen by punching holes through their cell surface membranes so the cell contents spill out. This is called cell lysis.
What is another name for T helper cells?
CD4+
