cell recognition and the immune system Flashcards
what are the 2 forms of of responses with the white blood cells for defence?
– cell-mediated responses involving T lymphocytes
– humoral responses involving B lymphocytes
what does protein molecules usually allow the immune system to identify?
– pathogens
– non-self material such as cells from other organisms of the same species
– toxins including those produced by certain pathogens
– abnormal body
how do lymphocytes recognise cells belonging to the body?
– lymphocytes are constantly colliding with other cells
– lymphocytes will collide almost exclusively with the body’s own material
– lymphocytes will have receptors that exactly fit those of the body’s own cells
what is the summary of phagocytosis?
– chemical products of pathogens or dead and damaged cells cause phagocytes to move towards the pathogens
– receptors on phagocytes attach to chemicals on pathogen surface
– engulf pathogen to form phagosome
– lysosome move towards vesicle
– lysozymes present within the lysosome ingested bacteria by hydrolysis
what is an antigen?
an antigen is any part of an organism or substance that is recognised as non-self by the immune system and stimulates and immune response
what are the two types of lymphocytes?
– b lymphocytes
– T lymphocytes
what is a b lymphocyte?
– in bone marrow
– associated with humoral immunity where they are involved with antibodies
what is a T lymphocyte?
– matures in thymus gland
– associated with cell-mediated immunity
what are the stages of response of T lymphocytes to infections by pathogens?
– pathogens invade body cells
– phagocyte places antigens from the pathogen on its cell-surface membrane
– receptors on a specific helper T cell fit exactly onto these antigens
– this attachment activates the T cell to divide rapidly by mitosis and form a clone or genetically identical cells
– cloned T cells can develop into memory cells
what is and antibody?
antibodies are proteins with specific binding sites synthesised by B cells produces a specific antibody.
what are the 2 ways antibodies assist in destruction of pathogen?
– cause agglutination of the bacterial cells
– serve as markers that stimulate phagocytes to engulf the bacterial cells to which they are attached
what are monoclonal antibodies?
single type of antibody that can be isolated and cloned
describe monoclonal antibody theory
– monoclonal antibodies are produced specific to antigens on cancer cells
– these antibodies are then given to a patient and attach themselves to the receptors
– they attach to the surface of their cancer cells and block the chemical signals that stimulate their uncontrolled growth
how are monoclonal antibodies used in medical diagnosis
used in cancer diagnosis as higher levels of specific antigen in the blood.
how are monoclonal antibodies used in pregnancy testing?
placenta produces a hormone that is found in urine and monoclonal antibodies are on the strip and are linked to colour particles
what are some ethical issues with the use of monoclonal antibodies?
– production of these involves mice
– patients must be given full knowledge of risk and benefits
– issues of conduct of drug trials
What is passive immunity?
– produced by the introduction of antibodies into individuals from an outside source.
– no direct contact with pathogen
– no memory cells
what is active immunity?
– produced by stimulating the production of antibodies by the individuals immune system
– direct contact with pathogen is necessary
what is natural active immunity?
body produces its own antibodies and continues for many years
what is artificial active immunity?
immunisation
what makes a vaccination programme successful?
– economically available
– few side-effects
– storing and transporting vaccine must be available
– must be means of administering vaccine properly at appropriate time
– herd immunity
why might a vaccine not eliminate disease?
– vaccination may fail to induce immunity in certain individuals
– individuals may develop disease immediately after vaccine so not have high immunity yet
– pathogen may mutate frequently
– may be varieties of a pathogen
– people may have religious values against vaccinations
what are the ethics of using vaccines?
– use of animals
– side-effects
– trials
– testing
what are the important components of HIV?
– attachment proteins
– capsid
– lipid envelope
– matrix
– reverse transcriptase
– genetic material (RNA)
how does HIV replicate?
– HIV enters bloodstream
– protein on HIV readily binds to a protein called CD4 and attaches to helper T cells
– protein capsid fuses with the cell-surface membrane. The RNA and enzymes of HIV enter the helper T cell
– HIV reverse transcriptase converts the virus’s RNA into DNA
– newly made DNA moved into helper T cell’s DNA and is moved into its DNA
– HIV DNA in the nucleus creates messenger RNA using the cell’s enzymes
– mRNA passes out of the nucleus through a nuclear pore and uses the cell’s protein synthesis mechanisms
– the HIV particles break away from the helper T cells
how does HIV cause the symptoms of AIDS
– it kills or affects the normal functioning of helper T cells
– memory cells can also be effected so immune system is weekend.
what is the ELISA test
antibodies are used to detect the presence of a protein in a sample and the quantities of them.
describe the procedure of the ELISA test
– apply sample to a surface with antigens attached
– wash surface several times to remove ant unattached antigens
–add antibody that is specific to the antigen we are trying to detect and leave the two to bind together
– wash the surface to remove excess antibody
– add a second antibody that binds with the first antibody which has an enzyme attached to it
– add the colourless substrate of the enzyme
– amount of antigen present is relative to the intensity of colour that develops
