The specific immune system 12.6 Flashcards
What are antigens
- protein molecules present on the surface of cells which trigger immune responses
What are antibodies
- Y-shaped glycoproteins called immunoglobulins found in the blood that bind to antigens/toxin
How long does the specific immune system take to respond
- inital invasion can take up to 14 days
- upon seconday invasion, 3-5 days
What is the structure of antibodies
- made of 4 chains in total (2 heavy and 2 light chains)
- disulfide bonds form between heavy and light chains and also between the 2 heavy chains
Explain how antibodies work to bind to antigens
- bind based on lock and key mechanism (complementary antigen and antibody)
What is the variable region
- forms the antibody binding site
- part of the antibody made from both variable light and heavy chain region
What is the constant region
Every part of the antibody except the binding site (variable region)
what is produced when a antigen and antibody bind together
- an antigen-antibody complex
what is the hinge region
- flexible stretch of antibody where heavy and light chains form disulfide bonds
What is the function of the hinge region of an antibody
The hinge region of the antibody provides the molecules with flexibility, allowing it to bind 2 separate antigens, one at each of its antigen-binding sites
- What are agglutinins
- how do they aid immunity
- Chemicals that cause pathogens to clump together
- aiding phagocytosis, helps slow spread of pathogen
What are the different types of lymphocytes
There are T lymphocytes and B lymphocytes
What are the types of T lymophocytes
- T killer cells
- T helper cells
- T memory cells
- T regulator cells
what are the types of B lymphocytes
- Plasma cells
- B effector cells
- B memory cells
Features of T helper cells
- receptors on membranes bind to antigens on APCs
- produce interleukins (type of cell signalling molecule) which stimulate B cells to:
- increase antibody production
- T cell production
- stims phagocytosis of APC
APC= antigen presenting cell
What are T killer cells
- destroy APC
- produce chemical called perforin, which forms holes in the cell membrane so it’s freely permeable
^kills cell
APC=anti-gen presenting cell
features of t memory cells
- live for a long time
- part of the immunological memory.
- If they meet an antigen a second time, they rapidly produce a huge number of T killer cells (clonal expansion) that destroy the pathogen
What are T regulator cells
- cells suppress immune system once pathogen been eliminated
- make sure body recognise self antigens
^interleukins play role in this
what are plasma cells (B lymphocytes)
- cells that produce antibodies to a particular antigen
What are B effector cells
These divide to form plasma cell clones
plasma cells produce antibodies to particular antigens
What are B memory cells
- lives for a very long time
- part of immunological memory
- programmed to remember specific antigen and the antibody that binds to it
^gives body rapid response to pathogen presenting this antigen
What is cell-mediated immunity
- T lymphocytes respond to the cells of an organism that have been changed in some way, for example by a virus infection, by antigen processing or by mutation (for example cancer cells) and to cells from transplanted tissue
What are the steps of the cell-mediated response
1)In the non-specific defence system, macrophages engulf and digest pathogens in phagocytosis. They process the antigens from the surface of the pathogen to form antigen-presenting cells (APCs).
2)The receptor on some of the T helper cells fit the antigens. These T helper cells become activated and produce interleukins, which stimulate more T cells to divide rapidly by mitosis. They form clones of identical activated T helper cells that all carry the right antigen to bind t a particular pathogen
3)The cloned T cells may:
- develop into T memory cells, which give a rapid response if this pathogen invades the body again
- produce interleukins that stimulate phagocytosis
- produce interleukins that stimulate B cells to divide
- stimulate the development of a clone of T killer cells that are specific for the presented antigen and then destroy infected cells.
What is humoral immunity
- Component of immune system involving the production of antibodies by B cells and secreting them into the blood and lymph fluid
what are the steps of humoral immunity
1)Activated T helper cells bind to the B cell APC. This is clonal selection (the point at which the B cell with the correct antibody to overcome a particular antigen is selected for cloning
2)Interleukins produced by the activated T helper cells activate the B cells.
3)The activated B cell divides by mitosis to give clones of plasma cells and B memory cells. This is clonal expansion
4)Cloned plasma cells produce antibodies that fit the antigens on the surface of the pathogen, bind to the antigens and disable them, or act as opsonins or agglutinins. This is the primary immune response and it can take days or even weeks to become fully effective abasing a particular pathogen. This is why we get ill - the symptoms are the result of the way our body reacts when the pathogens are dividing freely, before the primary immune response is fully operational
5)Some cloned B cells develop into B memory cells. If the body is infected by the same pathogen again, the B memory cells divide rapidly to from plasma cell clones. These produce the right antibody and wipe out the pathogen very quickly, before it can cause the symptoms of disease. This is the secondary immune response.
What is clonal selection
The process of matching the antigens on an antigen presenting cells with the antigen receptors on B and T lymphocytes.
What is clonal expansion
production of many genetically identical daughter cells through cell division of the activated B or T lymphocyte after clonal selection.
what is an autoimmune disease
- when the immune system stops recognising your own cells and attacks them
Why do people develop autoimmune disease
- genetic predisposition
- in reponse to some types of pathogens
What can be used to treat autoimmune responses
- immunosuppressant drugs
what are the functions of interleukins produced by T helper cells
- activate B cells to produce antibodies and stimulate T cell production
- attract and stimulate macrophages to ingest pathogens with antigen-antibody complexes
- What are opsonins
- how do they aid immunity
- Anantibody that binds to a antigen marking it out for phagocytosis
