5Teacher slideHow does the baterica / virus / foreign body get into our bodies?(and what do we have to stop it)Through:Skin: physical barrier & sebaceous glands - oilCuts / wounds: clots / scabsEyes : tears lysozyme enzyme dissolves cell wallsMouth: lysozyme in salivaNose: cilia, mucous to trap bugsStomach: hydrochloric acidVagina – lactic acid bacteria prevents growth of other bacteriaCalled first line of general defence
7Teacher slide Once a pathogen gets in, what happens then? White blood cells eat them up (phagocytes)Some phagocytes are very big and live a long time looking for pathogens – MacrophagesDefence Proteins(Complement) causes pathogens to burstInterferons – prevents viral multiplication
8Teacher slide Once a pathogen gets in, what happens then? Inflammation Cells get infected they release chemical call histamineBlood capillaries open wider + become porousCauses swelling, redness heat and painInflammation in whole body and inc temp = fever
9Human Defence System General Defence System Non-specific Skin, Mucous Membranes & secretions(physical barriers)White blood cells & chemicals to destroy any pathogens that penetrate the body(biochemically inside body)
10Human Defence System Specific Defence System (Immune System) Attacks specific pathogens by:Producing AntibodiesKilling infected cells
111st line of General Defence System SkinPhysical barrier that prevents pathogens getting throughClottingIf skin is broken, blood clotting prevents entry of pathogens
121st line of General Defence System LysozymeEnzyme found in sweat, tears & salivaAttacks & dissolves bacterial cell wallsSebaceous GlandsChemicals that kill bacteria are released in the oil
131st line of General Defence System MucousLines many body systemsTraps pathogensAcidHCl in stomach kills many pathogens
141st line of General Defence System CiliaLines respiratory systemBeat and move mucous to stomachCoughing helps to move this mucousBeneficial BacteriaLactic acidPrevents growth of pathogens
15Recap Quiz What are Foreign bodies/cells that cause disease ? PathogensIs the general defence system specific or non-specific?Non-specificWhat is the first line of defence of the general defence system?Skin, mucous membranes & secretions
16Recap Quiz How does the specific defence system work? By producing antibodies & killing infected cellsWhere would you find lysozyme?Tears, sweat, & salivaWhat does it do?Dissolve cells walls of bacteria
172nd line of general defence White blood cellsDefence ProteinsInflammation
182nd line of general defence WBCPathogen invades cellReleases chemicalsAttracts WBCWBC Phagocytes engulf bacteria
30Attack body cells which contain antigens on surface of cell LymphocytesAttack body cells which contain antigens on surface of cellorAttacks cancer cellsProduces ANTIBODIES
31Recap What are the components of the 2nd line of general defence? White blood cellsDefence ProteinsInflammation
32Recap How do the white blood cells work? Attracted by chemicals to the infected cell and engulf bacteriaWhat are the defence proteins?ComplementInterferons
33Recap What do the complement proteins do? They cause a chain reaction which bursts cellsWhat do the interferons do?They prevent viral multiplicationHow does inflammation work?Produces heat, swelling, pain and redness and interferes with pathogen reproduction
34Recap How does the specific defence system work? It produces antibodies & WBC kill infected cellsWhat are the WBC involved?Lymphocytes & Monocytes
35Recap How do the monocytes work? They become macrophages and digest pathogensHow do the lymphocytes work?They attack infected cells and they produce antiboides.
36ObjectivesUnderstand the antigen – antibody response
37Antigens Antibody generating Foreign molecule stimulates production of antibodiesTeacher notes:Antigens include molecules from the coats of viruses and cell walls of bacteria, fungi and other micro organismsAntigens are also found in parts of foreign cells e.g. pollen grainsDoes anybody know what happens when the above scenario takes place?Allergic reactionOther places you will find antigens are on incompatible blood transfusions, transplanted organs and cancer cells
38AntibodyIs a protein produced by white blood cells (called lymphcytes) in response to an antigen
39Antibodies Part of family of proteins called IMMUNOGLOBULINS Pathogens can display large number of antigens on its surfaceMany similar shaped antibodies bind to antigens on surface of pathogen
401. Antibodies attach to antigens Stops pathogen entering new cell2. Cause pathogens to clump togetherAllows phagocytes to destroy pathogens3. Trigger Complement systemPathogenic cells are burstThe antigen – antibody reaction is highly specifici.e. there is a precise fit between antibody and antigenEach antigen stimulates the production of only one antibody
41How antibodies dispose of antigens Antibodies attach to antigensStops pathogen entering new cellCause pathogens to clump togetherAllows phagocytes to destroy pathogensTrigger Complement systemPathogenic cells are burst
42How long does immunity last? 2nd contact – 5 days1st contact – 14 daysTeacher notes:Ask students how long immunity lasts?e.g. if you have the measles as a child and are exposed to them as an adult will you get the measles again? Why?After an infection is overcome, antibody producing lymphocytes stay in the body for a long time.If you are exposed to the same antigen again, the lymphocytes can quickly produce large amount of the specific antibodiesSo you won’t suffer from the same infection 2nd time roundOn first contact with a pathogen it takes up to 14 days to produce the max number of antibodiesSecond time exposed to the same pathogen (antigen) it only takes 5 days to produce antibodies in large numbers
43What about colds & flus? Why do we keep getting colds and flus? Many different formsEach have different antigensMutate constantly
44Problems with antigen-antibody reaction Reaction is disabled in people who have AIDSCan produce antibody against own bodyAllergiesTeacher notes:The importance of antibody-allergen reaction is illustrated in people who have AIDS as it is disabled in these people. I.e. they can’t fight infectionSometimes our own bodies produce antibodies against our own tissues e.g. rheumatoid arthritis – joints are attacked or MS where the myelin sheath of nerve cells is attackedAllergies occur when our bodies produce antibodies against materials which should not be antigenic e.g. pollen, food, dust mites etcTherefore allergies are said to be inappropriate immune responses
45Recap What is an antigen? Foreign molecule stimulates production of antibodiesWhat is an antibody?Is a protein produced by white blood cells (called lymphcytes) in response to an antigen
46RecapWhat is the name of the family of proteins that antibodies are from?ImmunoglobulinsHow do antibodies dispose of antigens?Antibodies attach to antigensStops pathogen entering new cellCause pathogens to clump togetherAllows phagocytes to destroy pathogensTrigger Complement systemPathogenic cells are burst
47Recap How long does immunity last? After an infection is overcome, antibody producing lymphocytes stay in the body for a long time.Name 3 problems associated with antibody-antigen interactionDisabled in AIDS patientsCan cause autoimmune disorders (RA & MS)Can cause allergies (inappropriate immune responses)
48Induced ImmunityIs the ability to resist disease caused by specific pathogens by the production of antibodies2 types of induced immunityActive ImmunityPassive Immunity
49Active immunityProduction of a person’s own antibodies in response to antigens that enter bodyDevelops after person is infected by virus or bacterium or vaccinationLong-lasting as lumphocytes that make the antibody have a long life
50Active immunity Natural Artificial Active Active Immunity Immunity Teacher notes:Ask what do you think this means?Natural is the normal way ie we get infected with a pathogen in the normal way and artificial is when we are immunised
51Natural Active Immunity Occurs when we get infected in normal waye.g. when we get infected with cold / flu/ chicken pox etc…We develop natural immunity by producing antibodies
52Artificial Active Immunity Occurs when we are immunised i.e. get a vaccineA vaccine is a non disease causing dose of a pathogen (or toxin) which triggers the production of antibodies
53What is a vaccine? Can contain pathogens that are killed May be only the outer wall / coat of pathogen (this is where the antigens are)Sometimes it is a bacterial toxinSometimes it is a genetically engineered antigen (no risk of infection)
54Develops antibodies to pathogen How does a vaccine work?Receives the vaccineDevelops antibodies to pathogenNo symptoms infectionLife long immunityNotes:The ability to make these antibodies persists in the body conferring life long immunity
55History of vaccines Teacher notes: Ask if anyone knows who this is? Edward JennerThe first vaccine was given by EJ in 1796Jenner had learned that milk maids who had suffered cow pox ( a non fatal viral infection) were resistant to small pox (fatal usually)Jenner inoculated cowpox virus into a young boy.6 weeks later he inoculated the young boy with small poxLuckily the boy survivedCowpox and smallpox have similar antigens, once the boy had produced antibodies to the cowpox he was immune to smallpoxVacca is the latin for cow and hence VaccineSmallpox was eradicated in 1976 and now exists only in a laboratory in the USA and Russia
56Vaccinations What types can you think of? TB, Diptheria Whooping cough MMRFluMeningitis
57Passive immunity Natural Artificial Passive Passive Immunity Immunity Teacher notes:Ask what do you think this means?Natural passive immunity occurs when a mother passes on immunity either across the placenta or through breast milkartificial Passive immunity is when a person gets an injection of antibodies from another source
58Natural Passive Immunity Child gets antibodies from motherThrough the placentaBreast milkHow long?Only lasts for first few months of life
59Artificial Passive Immunity When a person is given an injection containing antibodies from another organismAntibodies act fast to control diseaseDo not last long – are broken downE.g. anti-tetanus injectionNotes:In anti-tetanus injection the antibodies are are extracted from blood of horses with tetanus.The horse antibodies are given to an infected person.
60Recap What are the 2 types of induced immunity called? Active and PassiveWhat is Active immunity?Antibodies produced in person’s own body2 types of active immunity what are they?Natural and artificialNotes:In anti-tetanus injection the antibodies are are extracted from blood of horses with tetanus.The horse antibodies are given to an infected person.
61Recap What is natural active immunity? When pathogens enter the body naturally and you produce antibodies in responseWhat is artificial active immunity?When a pathogen is introduced artificially like vaccineNotes:In anti-tetanus injection the antibodies are are extracted from blood of horses with tetanus.The horse antibodies are given to an infected person.
62Recap What is Passive immunity? Antibodies from another organism enter a person’s bodyThere are 2 types, what are they?Natural passive immunityArtificial passive immunityNotes:In anti-tetanus injection the antibodies are are extracted from blood of horses with tetanus.The horse antibodies are given to an infected person.
63Recap What is natural passive immunity? Antibodies enter a body through natural meansWhat are natural means?Breast milkThrough the placentaNotes:In anti-tetanus injection the antibodies are are extracted from blood of horses with tetanus.The horse antibodies are given to an infected person.
64Recap What is natural artificial immunity? Antibodies are injected into a personAn example?Anti-tetanus injectionsNotes:In anti-tetanus injection the antibodies are are extracted from blood of horses with tetanus.The horse antibodies are given to an infected person.
65Lymphocytes What are lymphocytes? White blood cells Where are they formed?Bone MarrowWhat is their structure?Large round nucleus and very little cytoplasm
66Lymphocytes White blood cells Formed in the Bone Marrow their structure is Large round nucleus and very little cytoplasm2 typesB-lymphocytes – mature in Bone marrowT-lymphocytes – mature in Thymus gland
67B-Lymphocytes / B-cells Mature in bone marrowMove to lymphatic tissue especially spleen and lymph nodesMillions of different types of B cellsEach B-cell recognises only one antigen & only produces one type of antibody
68B-cells B-cell comes into contact with its specific antigen It divides to produce identical B cellsThese B-cells are called Plasma cellsThese produce large numbers of the required antibodyPlasma cells only live a few days but produce 2000 antibody molecules per second
70B-cells How do antibodies inactivate antigens? They attach to them and this allows the cells carrying the antigen to be disposed of by phagocytes or by activating complement (which bursts cells)
71B-cells Most die off once the infection has been overcome Some remain alive for yearsSurviving B-cells allow the body to respond if the same antigen enters the bodyThis secondary response is more effective ?Why
72B-cells This secondary response is more effective ? Produces antibodies in response to much smaller amounts of antigenProduces antibodies much faster (5 days as opposed to 14 days)Produces much greater number of antibodiesThese factors prevent us from being infected more than once by the same pathogen
73T-cells Move from bone marrow to thymus where they become activated Important in early months and years of lifeDo not produce antibodiesAct against viruses and bacteria
751. Helper T-cells Recognise antigens on surface of other cells Antigens activate helper T-cellsT-cells multiply and enlarge and form a group of helper T-cells
761. Helper T-cellsGroup secretes chemicals e.g. interferons (which prevent viral replication)Chemicals stimulate production & activation of antibody producing B-cellsAlso stimulates Killer T-cells to reproduceHIV infects helper T-cells (VIDEO)
772. Killer T-cells Attack abnormal body cells i.e. virus infected or cancer cellsStimulated by Helper T-cellsRelease PerforinPerforin makes pores in the membrane which causes cells to burstCytotoxic cells
793. Suppressor T-cells Growth is stimulate by specific antigens Grow more slowly than other T-cellsBecome active once pathogen is destroyedInhibit B-cells and other T-cellsControl and stop immune response
804. Memory T-cells Survive for a long time Lifetime Stimulate B-cells to produce antibodiesTrigger production of killer T-cells
81Recap What are lymphocytes? White blood cells Where are they formed? Bone MarrowWhat is their structure?Large round nucleus and very little cytoplasm
82Recap Where do B-cells mature Bone marrow Where do T-cells mature? ThymusA number of identical B-cells are called?Plasma cellsWhat do they do?Produce antibodies
83Recap Describe the secondary response? This secondary response is more effective ?Produces antibodies in response to much smaller amounts of antigenProduces antibodies much faster (5 days as opposed to 14 days)Produces much greater number of antibodies
84Recap How many types of t-cells? 4 types Helper T-cells Killer T-cells Supressor T-cellsMemory T-cellsWhat does each one do?Helper T – produce chemicals that stimulate b-cells to produce antibodies
85RecapKiller T cells?Produce perforin which causes abnormal body cells to burstSuppressor t cellsTurn off immune systemMemory t cellsSurvive a long time to trigger immunity to the same antigen later in life.