Immunity Flashcards
what is immunity?
means by which body protects itself against infection
how does body identify differnt type of cells?
- each type of cell have specific molecules on surface that identify it
- proteins have specific tertiary structure and wide varietyw=
- enable immune system to identify - pathogens/ non-self mterials/ abnormal cells/ toxins
what is an antigen?
a foreign ‘non-self- protein found on surface on a cell
what are the two types of immune response/?
- non-specific
- specific
what is non-specific immunity?
same for all cells - immediate response
what is specific immunity?
specific for all cells - slower response
what are the first line of defence in non-specific immunity?
physical/chemical barriers - e.g. skin/mucus/stomach acid
what is phagocytosis?
macrophages ingest and destroy pathogens
what are the seven stages of phagocytosis?
chemotaxis ingestion phagosome phagolysosome digestion residual body waste discharge
mnemonic to remember stages of phagocytosis
- chris
- is
- peculiarly
- pale
- during
- recess
- (on) wednesdays
what is the other type of phagocyte and how does it differ to a macrophage?
- neutrophil
- moon-shaped nucleus
- short-lived - dies after digesting nucleus and dead neutrophils form pus
- does not initiate cell-mediated response
what are the two types of specific response? what lymphocytes are involved?
- cell-mediated response - T-lymphocytes
- humoral response - B-lymphocytes
how do T-lymphocytes respond to infection?
antigens presented on surface of cell membranes
what are antigen-presenting cells? give examples
cells that can present antigens of other cells on their membrane
- macrophage (phagocyte)
- virus- invaded body cells
how do helper-T cells work?
- specific binding - protein receptors complementary to antigen
- clonal selection - find clones of T-helper cell
- clonal expansion - divide rapidly by mitosis
what four options does a helper-T cell have after clonal expansion?
- memory cell
- cytotoxic cell
- secretes cytokines to phagocytes
- secretes cytokines to B-lymphocytes
how do cytotoxic cell kill cells?
- produce perforin - hole in membrane
- inject toxins
- freely permeable to all substances
- so cell is killed
how does humoral response work?
- specific binding - antibodies specific to receptor
- clonal selection/expansion - more antibodies produced (monoclonal)
what are the primary and secondary response with humoral immunity?
primary response - produce plasma cells - secreted into plasma/ destroy cells
secondary response - produce memory cells - if infected again, divide and reproduce quickly
what are immunoglobulins?
antibodies = proteins produced by B lymphocytes in response to antigen
what type of protein structure does it have?
quatenary structure - consists of 4 polypeptide chains - 2 heavy and 2 light chains
what is the variable region?
region which differs in each antibody as it is specific
- the shape of binding site is determined by order of amino acid
what type of bonds hold structure together?
disulphide bridges
how do immunoglobulins work?
- agglutination - clump bacterial cells together using 2 binding sites
- act as labels for phagocytosis
- produce antitoxins
what does the hinge region do?
provides flexibility to allow variable region to move which facilitates binding of antigen
what are monoclonal antibodies?
single clones of anitbody
name three ways monoclonal antibodies are used?
- pregnancy testing
- medical diagnosis
- in conjunction with therapeutic drugs
how does pregnancy test work?
- placenta produces hormone - hCG( human chorionic gonadatrophin)
- if present in urine, bind to antibodies
- form antibody-antigen complex move up strip and produce coloured line by attachment of another anitbody producing coloured particles
how are monoclonal antibodies used in medical diagnosis of prostate cancer?
- if have cancer, high levels of PSA (prostate specific antigens) in blood
- use specific antibodies to interact wth antigens
- used as a measure of PSA level - provide early warning of possibility and precursor to further testing
what are the two forms of monoclonal antibody therapy?
- direct
- indirect
how does direct monoclonal antibody therapy work in cancer treatment?
antibodies attach to cancer cells and block chemical signals to stimulate growth
how does indirect monoclonal antibody therapy work in cancer treatment?
attach cytotoxic drug to antibody which kills cancer cells
why is indirect monoclonal antibody therapy used in small doses?
- cheaper costs
- reduces side effects
what are the three main ethical issues with use of monoclonal antibodies?
- use of mice: induce cancer into mice - guidelines of suffering
- drug trials dangerous may have adverse effects
- many risks as well as advantages - all patients must be informed before consent
