Immunology Flashcards
(23 cards)
Define antigen
Antigen is a molecule that stimulates an immune response that results in the production of a specific antigen
Explain Phagocytosis process
- Pathogen engulfed by phagocyte
- Engulfed pathogen enters cytoplasm of phagocyte by vesicle, now called phagasome
- Lysosome fuses with phagosome which releases hydrolytic digestive enzymes
- Lysosome enzymes hydrolyses pathogen
- Waste material released by exocytosis
- Phagocyte becomes antigen presenting cell
How does phagocyte finds pathogens?
Phagocyte can detect chemicals signals produced by pathogens
What are phagocyte
A group of white blood cells
What type of immunity is phagocytosis
Non specific immunity
What’s a negative about phagocytosis
- takes too long
- may results in damage to tissues & organs
Define specific cellular response
A specific response to a specific antigen on the surface of a cell or pathogen that has been recognised as non self
What type of response is cell mediated response
Primary response
What could be an antigen presenting cell
- phagocyte
- Abnormal cells
- Cells from transplant
- Infected body cells
What does cell mediated response involve
- Involves the response of T lymphocytes to a foreign antigen
- only responds to antigens on the surface of cells
Explain the process of cell mediated immunity
- Phagocyte engulfs and hydrolyses pathogen and presents antigen on the cell surface membrane
- T helper cell specific receptor molecule binds to presented antigen
- Once T helper cell binds to antigen it is activated and rapidly clones by mitosis
- Cloned daughter cells can differentiate into different T cells
What are lymphocytes
White blood cells
Involved in specific immune response
Where are lymphocytes made
Bone marrow
Where do T cells mature
Thymus
When T helper cells are activated and many clones are being made, why does this method take place?
-Not enough room in the body to have lots of T cells for every antigen you encounter
-Increased number of cells would increased the total energy demands
What is the role of T helper cell
- Specific T helper cell binds to presented antigen
- Releases cytokines to attract phagocytes to an area of infection
- Releases cytokines to activate cytotoxic killer T cells
- Activates specifically complimentary B cells
- Forms memory T helper cell
What the role of cytotoxic killer T cells
- Locates and destroys infected cells that present the correct antigens
- Binds to antigen presenting cell
- Releases perforin which makes holes in the cell surface membrane which destroys antigen presenting cell
Explain the humoral response
- Specific T helper cell with correct receptor binds to presented antigen
- Located and activates the specifically complimentary B cell
- Specific T helper cell releases cytokine chemicals
- Signals specific B cells to clone by mitosis
- B cells can differentiate into Plasma cell or Memory B cell
What is plasma cell role
Produces vast quantities of antibody into blood plasma
What is memory B cell role
Remain in the blood to respond to pathogens rapidly and extensively should there be a future re infection
Describe antibody structure
- Constant region (same for all antibody)
- Variable region (have different primary & tertiary structure)
- Specific antigen binding sites ( forms antigen antibody complex)
- Receptor binding site
- Y shaped
- Quaternary structure
Definition of antibody
- Protein made in response to foreign antigen
- Binding site that binds to specific antigen
- Specific antibody produced from specific plasma cell
How does antibody assist in the destruction of pathogen
- Agglutination (antibody binds to antigen on pathogen and clumps them together)
- Opsonisation (marks pathogen so phagocytes able to identify and destroy pathogen more efficiently)
- Lysis (binds to antigen leading to destruction of cell membrane)
- Anti-toxins & Anti-venom (binds to toxin or venom to prevent a molecule from binding to complimentary target receptors)
- Prevents pathogen replication
