Immunity

Question 1

what is immunity?

Answer 1

means by which body protects itself against infection

Question 2

how does body identify differnt type of cells?

Answer 2

• 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

Question 3

what is an antigen?

Answer 3

a foreign ‘non-self- protein found on surface on a cell

Question 4

what are the two types of immune response/?

Answer 4

• non-specific

- specific

Question 5

what is non-specific immunity?

Answer 5

same for all cells - immediate response

Question 6

what is specific immunity?

Answer 6

specific for all cells - slower response

Question 7

what are the first line of defence in non-specific immunity?

Answer 7

physical/chemical barriers - e.g. skin/mucus/stomach acid

Question 8

what is phagocytosis?

Answer 8

macrophages ingest and destroy pathogens

Question 9

what are the seven stages of phagocytosis?

Answer 9

chemotaxis
ingestion
phagosome
phagolysosome
digestion
residual body
waste discharge

Question 10

mnemonic to remember stages of phagocytosis

Answer 10

• chris
• is
• peculiarly
• pale
• during
• recess
• (on) wednesdays

Question 11

what is the other type of phagocyte and how does it differ to a macrophage?

Answer 11

• neutrophil
• moon-shaped nucleus
• short-lived - dies after digesting nucleus and dead neutrophils form pus
• does not initiate cell-mediated response

Question 12

what are the two types of specific response? what lymphocytes are involved?

Answer 12

• cell-mediated response - T-lymphocytes

- humoral response - B-lymphocytes

Question 13

how do T-lymphocytes respond to infection?

Answer 13

antigens presented on surface of cell membranes

Question 14

what are antigen-presenting cells? give examples

Answer 14

cells that can present antigens of other cells on their membrane

• macrophage (phagocyte)
• virus- invaded body cells

Question 15

how do helper-T cells work?

Answer 15

• specific binding - protein receptors complementary to antigen
• clonal selection - find clones of T-helper cell
• clonal expansion - divide rapidly by mitosis

Question 16

what four options does a helper-T cell have after clonal expansion?

Answer 16

• memory cell
• cytotoxic cell
• secretes cytokines to phagocytes
• secretes cytokines to B-lymphocytes

Question 17

how do cytotoxic cell kill cells?

Answer 17

• produce perforin - hole in membrane
• inject toxins
• freely permeable to all substances
• so cell is killed

Question 18

how does humoral response work?

Answer 18

• specific binding - antibodies specific to receptor

- clonal selection/expansion - more antibodies produced (monoclonal)

Question 19

what are the primary and secondary response with humoral immunity?

Answer 19

primary response - produce plasma cells - secreted into plasma/ destroy cells
secondary response - produce memory cells - if infected again, divide and reproduce quickly

Question 20

what are immunoglobulins?

Answer 20

antibodies = proteins produced by B lymphocytes in response to antigen

Question 21

what type of protein structure does it have?

Answer 21

quatenary structure - consists of 4 polypeptide chains - 2 heavy and 2 light chains

Question 22

what is the variable region?

Answer 22

region which differs in each antibody as it is specific

- the shape of binding site is determined by order of amino acid

Question 23

what type of bonds hold structure together?

Answer 23

disulphide bridges

Question 24

how do immunoglobulins work?

Answer 24

• agglutination - clump bacterial cells together using 2 binding sites
• act as labels for phagocytosis
• produce antitoxins

Question 25

what does the hinge region do?

Answer 25

provides flexibility to allow variable region to move which facilitates binding of antigen

Question 26

what are monoclonal antibodies?

Answer 26

single clones of anitbody

Question 27

name three ways monoclonal antibodies are used?

Answer 27

• pregnancy testing
• medical diagnosis
• in conjunction with therapeutic drugs

Question 28

how does pregnancy test work?

Answer 28

• 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

Question 29

how are monoclonal antibodies used in medical diagnosis of prostate cancer?

Answer 29

• 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

Question 30

what are the two forms of monoclonal antibody therapy?

Answer 30

• direct

- indirect

Question 31

how does direct monoclonal antibody therapy work in cancer treatment?

Answer 31

antibodies attach to cancer cells and block chemical signals to stimulate growth

Question 32

how does indirect monoclonal antibody therapy work in cancer treatment?

Answer 32

attach cytotoxic drug to antibody which kills cancer cells

Question 33

why is indirect monoclonal antibody therapy used in small doses?

Answer 33

• cheaper costs

- reduces side effects

Question 34

what are the three main ethical issues with use of monoclonal antibodies?

Answer 34

• 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