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The Human Defence System. Human defence system How do we protect ourselves?

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Presentation on theme: "The Human Defence System. Human defence system How do we protect ourselves?"— Presentation transcript:

1 The Human Defence System

2 Human defence system How do we protect ourselves?

3 Teacher slide How do we protect ourselves against foreign bodies that cause disease (pathogens)? Possible answers: Antibodies, WBC, immune system Vaccines Antibiotics / drugs

4 How do I get in? How do I stop you?

5 Teacher slide How does the baterica / virus / foreign body get into our bodies?(and what do we have to stop it) Through: –Skin: physical barrier & sebaceous glands - oil –Cuts / wounds: clots / scabs –Eyes : tears lysozyme enzyme dissolves cell walls –Mouth: lysozyme in saliva –Nose: cilia, mucous to trap bugs –Stomach: hydrochloric acid –Vagina – lactic acid bacteria prevents growth of other bacteria –Called first line of general defence

6 “We’re in… now what?”

7 Teacher 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 – Macrophages –Defence Proteins (Complement) causes pathogens to burst Interferons – prevents viral multiplication

8 Teacher slide Once a pathogen gets in, what happens then? Inflammation –Cells get infected they release chemical call histamine –Blood capillaries open wider + become porous –Causes swelling, redness heat and pain –Inflammation in whole body and inc temp = fever

9 Human Defence System General Defence System Non-specific 1.Skin, Mucous Membranes & secretions (physical barriers) 2.White blood cells & chemicals to destroy any pathogens that penetrate the body (biochemically inside body)

10 Human Defence System Specific Defence System (Immune System) Attacks specific pathogens by: 1.Producing Antibodies 2.Killing infected cells

11 1 st line of General Defence System Skin –Physical barrier that prevents pathogens getting through Clotting –If skin is broken, blood clotting prevents entry of pathogens

12 1 st line of General Defence System Lysozyme –Enzyme found in sweat, tears & saliva –Attacks & dissolves bacterial cell walls Sebaceous Glands –Chemicals that kill bacteria are released in the oil

13 1 st line of General Defence System Mucous –Lines many body systems –Traps pathogens Acid –HCl in stomach kills many pathogens

14 1 st line of General Defence System Cilia –Lines respiratory system –Beat and move mucous to stomach –Coughing helps to move this mucous Beneficial Bacteria –Lactic acid –Prevents growth of pathogens

15 Recap Quiz What are Foreign bodies/cells that cause disease ? Pathogens Is the general defence system specific or non-specific? Non-specific What is the first line of defence of the general defence system? Skin, mucous membranes & secretions

16 Recap Quiz How does the specific defence system work? By producing antibodies & killing infected cells Where would you find lysozyme? Tears, sweat, & saliva What does it do? Dissolve cells walls of bacteria

17 2 nd line of general defence White blood cells Defence Proteins Inflammation

18 2 nd line of general defence Pathogen invades cell Releases chemicals Attracts WBC WBC Phagocytes engulf bacteria

19 2 nd line of general defence

20 Very large phagocytes = Macrophages Long life Some move around body looking for pathogens Some stay in fixed location (e.g. spleen, lymph nodes, tonsils, adenoids, appendix)

21 2 nd line of general defence Defence proteins Complement Interferon (set of 20 proteins) (set of defence proteins)

22 2 nd line of general defence Infection Activates Complement proteins Chain reaction Bursting of viruses & pathogens

23 2 nd line of general defence Infected body cell Produces interferon Stimulates cells to Prevent viral multiplication Spreads to other cells

24 2 nd line of general defence Infected cell Releases histamine Capillaries dilate Swelling /redness/ heat /pain Fight infection WBC

25 2 nd line of general defence Inflammation occurs over whole body Causes increased body temperature Called fever This interferes with the reproduction of viruses and bacteria

26 Specific Defence System (Immune System) Attacks SPECFIC pathogens 1.Produces Antibodies 2.WBC kill infected cells

27 Specific Defence System (Immune System) Bone Marrow White blood cells Lymphocytes Monocytes Move to blood vessels Lymph vessels, lymph nodes, Spleen, thymus gland

28 Monocytes Macrophages Digests pathogens Display antigens Antibody production

29 Macrophages Macrophage Antigens from pathogen

30 Lymphocytes Produces ANTIBODIES Attack body cells which contain antigens on surface of cell or Attacks cancer cells

31 Recap What are the components of the 2 nd line of general defence? White blood cells Defence Proteins Inflammation

32 Recap How do the white blood cells work? Attracted by chemicals to the infected cell and engulf bacteria What are the defence proteins? Complement Interferons

33 Recap What do the complement proteins do? They cause a chain reaction which bursts cells What do the interferons do? They prevent viral multiplication How does inflammation work? Produces heat, swelling, pain and redness and interferes with pathogen reproduction

34 Recap How does the specific defence system work? It produces antibodies & WBC kill infected cells What are the WBC involved? Lymphocytes & Monocytes

35 Recap How do the monocytes work? They become macrophages and digest pathogens How do the lymphocytes work? They attack infected cells and they produce antiboides.

36 Objectives Understand the antigen – antibody response

37 Antigens Antibody generating Foreign molecule stimulates production of antibodies

38 Antibody Is a protein produced by white blood cells (called lymphcytes) in response to an antigen

39 Antibodies Part of family of proteins called IMMUNOGLOBULINS Pathogens can display large number of antigens on its surface Many similar shaped antibodies bind to antigens on surface of pathogen

40

41 How antibodies dispose of antigens 1.Antibodies attach to antigens Stops pathogen entering new cell 2.Cause pathogens to clump together Allows phagocytes to destroy pathogens 3.Trigger Complement system Pathogenic cells are burst

42 How long does immunity last? 1 st contact – 14 days 2 nd contact – 5 days

43 What about colds & flus? Why do we keep getting colds and flus? Many different forms Each have different antigens Mutate constantly

44 Problems with antigen-antibody reaction Reaction is disabled in people who have AIDS Can produce antibody against own body Allergies

45 Recap What is an antigen? Foreign molecule stimulates production of antibodies What is an antibody? Is a protein produced by white blood cells (called lymphcytes) in response to an antigen

46 Recap What is the name of the family of proteins that antibodies are from? Immunoglobulins How do antibodies dispose of antigens? 1.Antibodies attach to antigens Stops pathogen entering new cell 2.Cause pathogens to clump together Allows phagocytes to destroy pathogens 3.Trigger Complement system Pathogenic cells are burst

47 Recap 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 interaction –Disabled in AIDS patients –Can cause autoimmune disorders (RA & MS) –Can cause allergies (inappropriate immune responses)

48 Induced Immunity Is the ability to resist disease caused by specific pathogens by the production of antibodies 2 types of induced immunity –Active Immunity –Passive Immunity

49 Active immunity Production of a person’s own antibodies in response to antigens that enter body Develops after person is infected by virus or bacterium or vaccination Long-lasting as lumphocytes that make the antibody have a long life

50 Active immunity NaturalArtificial Active Immunity

51 Natural Active Immunity Occurs when we get infected in normal way e.g. when we get infected with cold / flu/ chicken pox etc… We develop natural immunity by producing antibodies

52 Artificial Active Immunity Occurs when we are immunised i.e. get a vaccine A vaccine is a non disease causing dose of a pathogen (or toxin) which triggers the production of antibodies

53 What 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 toxin Sometimes it is a genetically engineered antigen (no risk of infection)

54 How does a vaccine work? Receives the vaccine Develops antibodies to pathogen No symptoms infection Life long immunity

55 History of vaccines

56 Vaccinations What types can you think of? TB, Diptheria Whooping cough MMR Flu Meningitis

57 Passive immunity NaturalArtificial Passive Immunity

58 Natural Passive Immunity Child gets antibodies from mother –Through the placenta –Breast milk How long?

59 Artificial Passive Immunity When a person is given an injection containing antibodies from another organism Antibodies act fast to control disease Do not last long – are broken down E.g. anti-tetanus injection

60 Recap What are the 2 types of induced immunity called? Active and Passive What is Active immunity? Antibodies produced in person’s own body 2 types of active immunity what are they? Natural and artificial

61 Recap What is natural active immunity? When pathogens enter the body naturally and you produce antibodies in response What is artificial active immunity? When a pathogen is introduced artificially like vaccine

62 Recap What is Passive immunity? Antibodies from another organism enter a person’s body There are 2 types, what are they? Natural passive immunity Artificial passive immunity

63 Recap What is natural passive immunity? Antibodies enter a body through natural means What are natural means? Breast milk Through the placenta

64 Recap What is natural artificial immunity? Antibodies are injected into a person An example? Anti-tetanus injections

65 Lymphocytes What are lymphocytes? White blood cells Where are they formed? Bone Marrow What is their structure? Large round nucleus and very little cytoplasm

66 Lymphocytes White blood cells Formed in the Bone Marrow their structure is Large round nucleus and very little cytoplasm 2 types B-lymphocytes – mature in Bone marrow T-lymphocytes – mature in Thymus gland

67 B-Lymphocytes / B-cells Mature in bone marrow Move to lymphatic tissue especially spleen and lymph nodes Millions of different types of B cells Each B-cell recognises only one antigen & only produces one type of antibody

68 B-cells B-cell comes into contact with its specific antigen It divides to produce identical B cells These B-cells are called Plasma cells These produce large numbers of the required antibody Plasma cells only live a few days but produce 2000 antibody molecules per second

69 B - Cells

70 B-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)

71 B-cells Most die off once the infection has been overcome Some remain alive for years Surviving B-cells allow the body to respond if the same antigen enters the body This secondary response is more effective ? Why

72 B-cells This secondary response is more effective ? Produces antibodies in response to much smaller amounts of antigen Produces antibodies much faster (5 days as opposed to 14 days) Produces much greater number of antibodies These factors prevent us from being infected more than once by the same pathogen

73 T-cells Move from bone marrow to thymus where they become activated Important in early months and years of life Do not produce antibodies Act against viruses and bacteria

74 T-cells 4 types  Helper T-cells  Killer T-cells  Supressor T-cells  Memory T-cells

75 1. Helper T-cells Recognise antigens on surface of other cells Antigens activate helper T-cells T-cells multiply and enlarge and form a group of helper T-cells

76 1. Helper T-cells Group secretes chemicals e.g. interferons (which prevent viral replication) Chemicals stimulate production & activation of antibody producing B-cells Also stimulates Killer T-cells to reproduce HIV infects helper T-cells (VIDEO)

77 2. Killer T-cells Attack abnormal body cells i.e. virus infected or cancer cells Stimulated by Helper T-cells Release Perforin Perforin makes pores in the membrane which causes cells to burst Cytotoxic cells

78 Killer T-cells

79 3. Suppressor T-cells Growth is stimulate by specific antigens Grow more slowly than other T-cells Become active once pathogen is destroyed Inhibit B-cells and other T-cells Control and stop immune response

80 4. Memory T-cells Survive for a long time Lifetime Stimulate B-cells to produce antibodies Trigger production of killer T-cells

81 Recap What are lymphocytes? White blood cells Where are they formed? Bone Marrow What is their structure? Large round nucleus and very little cytoplasm

82 Recap Where do B-cells mature Bone marrow Where do T-cells mature? Thymus A number of identical B-cells are called? Plasma cells What do they do? Produce antibodies

83 Recap Describe the secondary response? This secondary response is more effective ? Produces antibodies in response to much smaller amounts of antigen Produces antibodies much faster (5 days as opposed to 14 days) Produces much greater number of antibodies

84 Recap How many types of t-cells? 4 types  Helper T-cells  Killer T-cells  Supressor T-cells  Memory T-cells What does each one do? Helper T – produce chemicals that stimulate b-cells to produce antibodies

85 Recap Killer T cells? Produce perforin which causes abnormal body cells to burst Suppressor t cells Turn off immune system Memory t cells Survive a long time to trigger immunity to the same antigen later in life.

86 Recap


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