1. IMMUNITY Makes the bad pathogens die!

2. THE IMMUNE SYSTEM Involves The lymphatic system The circulatory system Bone marrow The lymphatic system can carry the plasma and white blood cells from the circulatory system Lymph nodes are a common ‘collection’ site

3. FOREIGN BODIES Any cells not recognised as ‘self’ cells ‘Self’ cells are recognised by the immune system by MHC (Major Histocompatibility Complex) markers on the surface MHC markers are specific antigens found on the surfaces of all cells MHC 1 Markers are found on all cells, except RBC MHC 2 Markers are found on immunity cells (B cells, T cells and some monocytes Cells lacking recognised MHC markers are deemed ‘non-self’ and attract an immune response Non-self markers that trigger a response of B cells or T cells are called antigens

4. SELF AND NON-SELF RECEPTORS

5. THREE LINES OF DEFENSE 1 st line non-specific Blocks foreign bodies from entering tissues 2 nd line non-specific Attacks foreign bodies in tissues 3 rd line Specific Has a ‘memory’ Involves cell differentiation

6. 1 ST LINE Mucous membranes Secreted by cells to ‘trap’ foreign particles Secretions Includes tears, mucous, sweat, etc Cilia Fine hairs lining the trachea Sweep foreign particles back to the oesophagus Skin Acts a barrier between internal environments (tissue) and external environments Natural flora Symbiotic bacteria

7. 2 ND LINE Phagocytes WBC which engulf and destroy foreign cells Neutrophils (made in bone marrow) Monocytes (made in bone marrow) Monocytes become macrophages when they enter the blood stream Natural Killer (NK) cells Acts on viral-infected cells Release perforins (protein) which act to lyse infected cells

8. COMPLEMENT PROTEINS About 20 types Made in the liver Inactive until infection occurs Antibody-antigen complex attracts them to site of infection Three ways to act Stick to the bacteria to aide identification Destroy membrane of pathogen Stimulate pahgocytes to become more active

9. INTERFERON Secreted by cells infected by virus Acts on local cells to avoid further infection Stimulates antiviral protein production C YTOKINES Protein messenger Messages between immunity cells Messages to nervous system Secreted by many cells (particularly T cells)

10. INFLAMMATION Controlled by multiple enzymes and compounds Mast cells, basophils and platelets all release messengers to encourage inflammation Inflammation involvse the dilation of blood vessels at the site of infection This brings more white blood cells It also accounts for the symptoms of swelling, redness and heat The first phagocytes to the area release histamine, this attracts more phagocytes Pus is generated from dead white blood cells containing the pathogen

11. 3 RD LINE OF DEFENSE Specific immunity Part of acquired immunity All lymphocytes originate in the bone marrow B cells mature and differentiate in the bone marrow Involved in humoral responses T cells Mature and differentiate in the thymus Involved in cell-mediated responses

12. TYPES OF CELLS B Cells Plasma cells B memory cells T Cells Th cells (T helper cells) Activated Th cells Th memory cells Tc cells (Cytotoxic T cells) Activated Tc cells Memory Tc cells

13. B CELLS Have antibodies (immunoglobulins ) on the surface Antibodies are made of protein chains and possess very specific receptors

14. TYPES OF IMMUNOGLOBULINS IgA (two molecules) Present in milk Active against viruses and some bacteria Present in tears and saliva IgD (single molecule) Role is unknown IgE (single molecule) Present in allergic reactions IgG (single molecule) Able to cross placenta and present in milk Active against viruses and some bacteria IgM (five molecules) Active against some bacteria and viruses

15. TYPES OF IMMUNOGLOBULINS

16. B CELLS Each B cell is specific for one type of antigen (it only has one type of receptor on its surface) Only a few copies of each B cell are created, so they all have slightly different DNA. This allows the immune system to respond to millions of antigens When an antigen enters the body it will quickly come into contact with the corresponding B cell

17. CLONAL-SELECTION THEORY When a particular B cells comes into contact with its antigen it quickly multiplies, creating many clones of itself Most of these clones become plasma cells and release antibodies Within a few days (when the infection subsides) the plasma cells die by apoptosis Some clones differentiate to become memory cells to create a long term protection against that antigen This means that if the pathogen strikes again the immune response will be much more rapid, a greater number of antibodies are produced during the second contact

18. PRIMARY AND SECONDARY RESPONSES

19. T CELLS Cell-mediated immunity T helper cells (Th cells) recognise antigens and stimulate B cells Cytotoxic T cells (Tc cells) destroy infected ‘self’ cells These cells have foreign antigens on the surface as well as MHC 1 markers The Tc cells recognises the foreign marker and secretes proteins to lyse the cell Tc cells are not effective against free virus particles Some Tc cells can also destroy cancerous cells

20. TYPES OF BLOOD CELLS

21. IMMUNITY CELLS

22. VACCINES

23. TYPES OF IMMUNITY Active immunity Receiving the pathogen and creating a normal immune response Memory cells created Passive immunity Infant receiving antibodies from the mother No memory created Active immunity Receiving immunisation (aka. vaccines or antigens) to create an immune response Memory cells created Passive immunity Receiving antibodies from an injection/serum No memory created NaturalInduced

24. VACCINE Contain dead or inactive micro-organisms’ Inactive organisms can be called attenuated, as they are still able to reproduce but cannot cause disease The antigens present in the serum create an immune response without causing disease This leads to a primary response, with memory cells being produced If a vaccinated person comes into contact with the live pathogen, they will have an immediate and increased immune response Toxoids, inactive toxins, can also be used in vaccines

25. ALLERGIES Mast cells release histamines creating contraction in smooth muscles This decreases the passage of area in the trachea and bronchi Mast cells are found in blood vessels and connective tissue in the gut and respiratory tract Large scale IgE production creates a stronger response, resulting in anaphylaxis IgE binds to mast cells to create a response IgE is released when ‘sensitive’ antigens are present Some people are more sensitive to antigens than others, as they have antibodies against that particular protein

26. AUTOIMMUNITY The immune system fails to recognise ‘self’ proteins B and T cells attack and destroy ‘self’ cells Examples: Systemic Lupus Erythematosus – major organs (esp. kidney) are not recognised as self Multiple sclerosis – the myelin sheath around nerves is not recognised as self Rheumatoid arthritis – joint cartilage is not recognised as self

27. ORGAN TRANSPLANTS Donor organs must match a certain number of markers in the recipient Biological family members often have a high number of matches due to similar DNA being shared T helper cells may recognise the grafted organ and attack it Transplant patients must receive drugs to suppress the action of T cells – eg. Cyclosporin suppresses T cells, meaning the immune system is still partially active

28. HUMAN BLOOD TYPES Your blood type is determined by the antigens present on your red blood cells O type people can only receive O type blood, as they have antibodies against A-antigens and B- antigens AB type people can receive any type of blood, because they have no antibodies against these antigens

29. COMPARISON OF BLOOD TYPE AND ANTIBODIES

30. RHESUS FACTOR The “positive” or “negative” in blood types refers to another protein The rhesus protein is either present (positive) or absent (negative) Negative blood types can only receive negative blood This can affect expectant mothers

31. RHESUS FACTOR IN PREGNANCY If the mother is Rh+ then no problems occur If the mother is Rh- problems can arise The first Rh+ fetus is unaffected, however at birth Rh+ blood cells can enter the mother, creating an immune response (the production of Rh antibodies If the mother becomes pregnant to a second Rh+ child, antibodies from the mother may enter the fetus causing harm A Rhesus negative mother can have injections after birth to remove the fetal blood cells from her bloodstream, reducing the immune response.

32. TESTING FOR BLOOD TYPES Blood is put in 4 wells Antibodies are added to the blood sample wells Anti-A is the antibody for antigen A, Anti-B is for antigen B and Anti-D is for the rhesus factor Agglutination is observed as clumping (indicating the presence of the antigen)

33. PLANT IMMUNITY Mechanical barriers Cuticle or waxy layers Cork cells creating galls Dropping infected leaves Chemical barriers Release of ‘gum’ to seal off infections Oils, acids and other chemical factors