1. Immunity

2. What is immunity? Immunity is the body's ability to fight off harmful micro-organisms –PATHOGENS- that invade it. Immunity is the body's ability to fight off harmful micro-organisms –PATHOGENS- that invade it. The immune system produces antibodies or cells that can deactivate pathogens. The immune system produces antibodies or cells that can deactivate pathogens. Fungi, protozoans, bacteria, and viruses are all potential pathogens. Fungi, protozoans, bacteria, and viruses are all potential pathogens.

3. What is an infectious disease? An infectious disease is one in which minute organisms, invisible to the naked eye, invade and multiply within the body. An infectious disease is one in which minute organisms, invisible to the naked eye, invade and multiply within the body. Many of these organisms are contagious, that is they spread between people in close contact. Many of these organisms are contagious, that is they spread between people in close contact.

5. The first person to identify microbes as causing disease was Robert Koch. The first person to identify microbes as causing disease was Robert Koch. We still use Koch’s Postulates in disease identification. We still use Koch’s Postulates in disease identification.

6. Koch’s Postulates 1. Pathogen must be found in the host in every case. 2. Pathogen must be isolated from the host and grown in pure culture. 3. When placed in a healthy host, pathogen produced in pure culture must cause the disease in the host. 4. Pathogen must be isolated from the new host and shown to be the original pathogen.

7. Endemic diseases are those found normally in a population. Endemic diseases are those found normally in a population. For example……. For example…….

8. An epidemic disease is a disease that many people acquire over a short period of time. An epidemic disease is a disease that many people acquire over a short period of time. For example……… For example………

9. A pandemic disease is a world-wide epidemic disease. A pandemic disease is a world-wide epidemic disease. For example………. For example……….

10. Innate Immune System- The body's first line of defense against pathogens uses mostly physical and chemical barriers such as Innate Immune System- The body's first line of defense against pathogens uses mostly physical and chemical barriers such as Skin Skin Sweat Sweat Tears Tears Saliva Saliva Mucus Mucus Stomach Acid Stomach Acid Macrophages and Neutrophils Macrophages and Neutrophils Inflammation Inflammation Interferons Interferons

11. Inflammatory response causes Inflammatory response causes Redness Redness Heat Heat Swelling Swelling Pain Pain

13. Where are T Cells and B Cells located?

14. Macrophages

15. B -Lymphocytes

16. Antibodies are specific to their antigen

17. Antibody Response After Exposure to Antigen

19. Antibodies Also known as immunoglobulins Also known as immunoglobulins Globular glycoproteins Globular glycoproteins The heavy and light chains are polypeptides The heavy and light chains are polypeptides The chains are held together by disulphide bridges The chains are held together by disulphide bridges Each ab has 2 identical ag binding sites – variable regions. Each ab has 2 identical ag binding sites – variable regions. The order of amino acids in the variable region determines the shape of the binding site The order of amino acids in the variable region determines the shape of the binding site

20. How Abs work Some act as labels to identify Some act as labels to identify antigens for phagocytes antigens for phagocytes Some work as antitoxins i.e. they block toxins for e.g. those causing diphtheria and tetanus Some work as antitoxins i.e. they block toxins for e.g. those causing diphtheria and tetanus Some attach to bacterial flagella making them less active and easier for phagocytes to engulf Some attach to bacterial flagella making them less active and easier for phagocytes to engulf Some cause agglutination (clumping together) of bacteria making them less likely to spread Some cause agglutination (clumping together) of bacteria making them less likely to spread

21. Vaccination A preparation containing antigenic material: Whole live microorganism Whole live microorganism Dead microorganism Dead microorganism Attenuated (harmless) microorganism Attenuated (harmless) microorganism Toxoid (harmless form of toxin) Toxoid (harmless form of toxin) Preparation of harmless ags Preparation of harmless ags

22. Vaccination Injection into vein or muscle Injection into vein or muscle Oral Oral

23. Vaccination Why aren’t they always effective? Natural infections persist within the body for a long time so the immune system has time to develop an effective response, vaccinations from dead m-os do not do this. Natural infections persist within the body for a long time so the immune system has time to develop an effective response, vaccinations from dead m-os do not do this. Less effective vaccines need booster injections to stimulate secondary responses Less effective vaccines need booster injections to stimulate secondary responses

24. Vaccination Why aren’t they always effective? Some people don’t respond well/at all to vaccinations Some people don’t respond well/at all to vaccinations Defective immune systems Defective immune systems Malnutrition particularly protein Malnutrition particularly protein

25. Vaccination Why aren’t they always effective? Antigenic variation caused by mutation Antigenic variation caused by mutation Antigenic drift – small changes (still recognised by memory cells) Antigenic drift – small changes (still recognised by memory cells) Antigenic shift – large changes (no longer recognised) Antigenic shift – large changes (no longer recognised)

26. Vaccination Why aren’t they always effective? No vaccines against protoctists (malaria and sleeping sickness) No vaccines against protoctists (malaria and sleeping sickness) Many stages to Plamodium life cycle with many antigens so vaccinations would have to be effective against all stages (or be effective just against infective stage but given in very small time period). Many stages to Plamodium life cycle with many antigens so vaccinations would have to be effective against all stages (or be effective just against infective stage but given in very small time period).

27. Vaccination Why aren’t they always effective? Sleeping sickness – Trypanosoma has a thousand different ags and changes them every 4-5 days Sleeping sickness – Trypanosoma has a thousand different ags and changes them every 4-5 days

28. Vaccination Why aren’t they always effective? Antigenic concealment parasites live inside body cells Antigenic concealment parasites live inside body cells Plasmodium – liver and blood cells Plasmodium – liver and blood cells Parasitic worms – cover themselves in host proteins Parasitic worms – cover themselves in host proteins HIV – live inside T-helper cells HIV – live inside T-helper cells

29. Smallpox Symptoms Red spots containing transparent fluid all over body. Red spots containing transparent fluid all over body. Spots fill with pus Spots fill with pus Eyelids swell and become glued together Eyelids swell and become glued together

30. Smallpox Mortality 12-30% died 12-30% died Survivors often left blind and disfigured with scabs. Survivors often left blind and disfigured with scabs.

31. Smallpox Eradication programme Started by WHO in 1956 Started by WHO in 1956 Aimed to rid world of smallpox by 1977 Aimed to rid world of smallpox by 1977 Involved vaccination and surveillance Involved vaccination and surveillance Over 80% of populations at risk of the disease were vaccinated Over 80% of populations at risk of the disease were vaccinated After any reported case everyone in the household and 30 surrounding households vaccinated – RING VACCINATION After any reported case everyone in the household and 30 surrounding households vaccinated – RING VACCINATION

32. Smallpox Eradication programme Last case of smallpox reported in Somalia in 1977 Last case of smallpox reported in Somalia in 1977 World declared free of smallpox in 1980 World declared free of smallpox in 1980

33. Smallpox Eradication programme – why was it successful? Variola virus stable -> cheap as everyone used same vaccine Variola virus stable -> cheap as everyone used same vaccine Vaccine made from harmless strain of similar virus (vaccinia) Vaccine made from harmless strain of similar virus (vaccinia) Vaccine could be used at high temperatures Vaccine could be used at high temperatures Easy to identify infected people Easy to identify infected people Smallpox doesn’t lie dormant in body Smallpox doesn’t lie dormant in body

34. Smallpox Eradication programme – why don’t all work? Political instability Political instability Poor infrastructure Poor infrastructure Unstable m-os Unstable m-os

35. Allergies When the immune system responds to harmless substances When the immune system responds to harmless substances Allergens – antigenic substances which do no real harm Allergens – antigenic substances which do no real harm Allergens include house dust, animal skin, pollen, house dust mite and its faeces Allergens include house dust, animal skin, pollen, house dust mite and its faeces

37. Allergies Histamine causes blood vessels to widen and become leaky. Histamine causes blood vessels to widen and become leaky. Fluid and white blood cells leave capillaries. Fluid and white blood cells leave capillaries. The area of leakage becomes hot, red and inflamed The area of leakage becomes hot, red and inflamed

38. Asthma Attacks can occur at any time Attacks can occur at any time Genes play a role in who develops asthma Genes play a role in who develops asthma Breathing becomes difficult, sufferers experience wheezing, coughing, a tightness about the chest and shortage of breath. Breathing becomes difficult, sufferers experience wheezing, coughing, a tightness about the chest and shortage of breath. 1/7 children in UK has asthma, number is increasing. 1/7 children in UK has asthma, number is increasing. >1000 people die each year from asthma every year in the UK >1000 people die each year from asthma every year in the UK

39. Asthma Airways in asthmatics are always inflamed, during an attack this worsens. Airways in asthmatics are always inflamed, during an attack this worsens. Fluid leaks from blood into airways and goblet cells secrete lots of mucus Fluid leaks from blood into airways and goblet cells secrete lots of mucus Airways can become blocked Airways can become blocked Muscles surrounding trachea and bronchioles contract which narrows airways further Muscles surrounding trachea and bronchioles contract which narrows airways further

40. Asthma Vaccines are being developed to make allergic responses less severe Vaccines are being developed to make allergic responses less severe Designed to desensitise people so they do not produce antibodies to allergens Designed to desensitise people so they do not produce antibodies to allergens Genetic tests may be used to screen children and then a vaccine could be given to prevent them developing asthma Genetic tests may be used to screen children and then a vaccine could be given to prevent them developing asthma

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