Specific immune system Flashcards
(27 cards)
What is antibodies?
- They are Y-shapeglycoproteins called immunoglobulins
- they bind to a specific antigen on the pathgen or toxin that has triggered the immune response
Describe the structure of antibodies
- Antigen-binding sites: complementary to a particular antigen on the pathogen
- Two light chain
- Two heavy chain
- Variable region: different on different antibodies due to different sequence of amino acid
- Constant region: same in all antibodies
- Disulfide bridges: strong bonds holding the antibodies in shape
- Hinge region: provide flexibility, allowing it to bind two seperate antigens, one at each of its antigen-binding sites
How antibodies defend the body
- The antibody of the antigen-antibody complex acts as an opsonin so the complex is easily engulfed and digested by phagocytes
- Agglutination: Pathogens carrying antigen-antibody complexs to clump together so phagocytes can engulf a number of pathogens at the same time
- Anti-toxins: They bind to toxins produced by pathogens and neutralise the toxin
- Most pathogens can no longer bind to the host cell as the antigens are blocked by the antibodies
What are the two types of lymphocytes in human body?
B lymphocytes (bone marrow)
T lymphocytes (thymus gland)
What is opsonin
- proteins that attach to the outside of cells or pathogens to tell phagocytes to swallow and destroy them.
- Acts as ‘tags’ on pathogens
What are the 4 T lymphocytes
T helper
T killer
T memory
T suppressor/ regulator
What does T killer do
- They destroy the pathogens by producing perforin
- This kills the pathogen by making holes in the cell membrance so it is freely permeable
What does T helper do
- They produce interleukins, which are a type of cytokine
- They stimulates B lymphocytes, which increases antibodies production
- They stimulates production of other types of T lymphocytes and attracta and stimulates macrophage to ingest pathogens with antigen-antibodies complex
What does T memory do
- Produce immunological memory
- If they meet an antigen a second time, they divide rapidly to form a huge number of clones of T killer that destroy the pathogen
What does T suppressor/ regulator do
They suppress immune system once the pathogen is eliminated
They ensure the body regconises self antigens and does not set up an autoimmune response
Interleukins are important in this control
What is cytokine
- Cell-signalling molecules produced by mast cells in damaged tissue.
- They attract white blood cells to the site of damage
What are the three types of B lymphocytes?
Plasma cell
B effector
B memory
What does plasma cell do?
They produce antibodies to a particular antigen and release them into the circulation
What does B effector do
They divide to form the plasma cell clones
What does B memory do
- Provide immunological memory
- remember a specific antigen and enable the body to make a very rapid response when a pathogen carrying that antigen is encountered again
What is cell-mediated immunity?
- T lymphocytes respond to the cells of an organism that have been changed in some way
- E.g. by a virus infection
- This is particularly important against virus and early cancers.
What is the processes of cell-mediated immunity?
- Macrophages engulf and digest pathogens in phagocytosis.
- They process the antigens from the suface of the pathogen to form antigen-presenting cells (APCs)
- The receptors on some of the T helper cells fit the antigens.
- These T helper cells become activated and produce interleukins, which stimulates more T lymphocytes to divide rapidly by mitosis.
- They form clones of identical activated T helper cells that all carry the right antigen to binds to a particular pathgen
- The cloned T lymphocytes may:
- develop into T memory cells, which gives a rapid response if this pathogen invades the body again
- Produce interleukins that stimulate phagocytosis
- Produce interleukins that stimulate B lymphocytes to divide
- Stimulate the developmetn of a clone of T killer that are specific for the presented antigen and then destroy infected cells
What is humoral immunity?
The body response to antigens found outside the cells, then produces antibodies that are soluble in the blood and tissue fluid and are not attached to cells
What is the process of humoral immunity?
- Activated T helper 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 - Interleukins produced by the activated T helper activate the B cells
- The activated B cell divides by mitosis to give clones of plasma cells and B memory cells. This is clonal expansion
- Cloned plasma cells produce complementary antibodies to the antigen, act as opsonins or agglutination. This is primary immune response
- Some cloned B cells develop into B memory. The B memory cells divide rapidly to form plasma cell clones. This is the secondary immune response
What is autoimmune disease?
When the immune system stops regconising ‘self’ cells and starts to attack healthy body tissue
What are three types of autoimmune disease?
- Type 1 diabetes
- Rheumatoid arthritis
- Lupus
What body part is affected by type 1 diabetes?
The insulin-secreting cells of the pancreas
What body part is affected by rheumatoid arthritis?
Joints - especially in the hands, wrists, ankles and feet
What body part is affected by Lupus?
- Often affects skin and joints and causes fatigue
- can attack any organ in the body including kidneys, liver, lungs or brain
