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UNIT THREE

UNIT THREE. BIOLOGY. AREA OF STUDY #2: DETECTING & RESPONDING EXAM REVISION LECTURE CHP 8: DEFENSE AGAINST DISEASE. CHP 8 TOPIC.1: The Lymphatic System. Function: 1.  take up excess tissue fluid and return it to the bloodstream (drained from thoracic duct into major veins)

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UNIT THREE

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  1. UNIT THREE BIOLOGY AREA OF STUDY #2: DETECTING & RESPONDING EXAM REVISION LECTURE CHP 8: DEFENSE AGAINST DISEASE

  2. CHP 8 TOPIC.1: The Lymphatic System Function: • 1.  take up excess tissue fluid and return it to the bloodstream (drained from thoracic duct into major veins) • 2.  absorb fats at the intestinal villi and transport to the circulatory system (90% of digested fat is absorbed this way) • 3.  defend against disease

  3. CHP 8 TOPIC 1: The Lymphatic System • key component of the immune system • blind ended open system, similar in structure • to veins, arteries and capillaries • returns proteins that leak out of capillaries • back into blood circulaltory system • White blood cells (leucocytes) move around in • the circulatory and lymphatic system seeking • foreign and damaged cells • lymphocytes (immune cells in the lymph • nodes) are produced by primary lymphoid • organs bone marrow, thymus) • immune responses cause swelling in • secondary lymphoid organs (lymphoid nodes, • spleen, tonsils, adenoids).

  4. CHP 8 TOPIC 1: The Lymphatic System Chapter 8 - Defence Against Disease

  5. CHP 8 TOPIC 1: The Lymphatic System Leukocytes, we will come back to these in more detail!

  6. Topic CHP 8.1 Questions: • Lymph vessels are open/ closed • Name two roles of the lymphatic system: _____________________, ________________, _______________________________ • Immune responses cause swelling in the _________________ ________________ organs • WBC are also known as: _________________ • Granular Leucocytes include: ____________________, _________________, ________________ • Agranular Leucocytes include T and B cells as well as: ________________________

  7. CHP 8 TOPIC 2: THREE LINES OF DEFENCE Immune System: Consists of Three Lines of Defence Chapter 8 - Defence Against Disease

  8. Non-specific mechanisms:Physical and Barriers: 1st line of defence CHP 8 TOPIC 3: NON-SPECIFIC IMMUNITY – 1ST LINE

  9. CHP 8 TOPIC 3: NON-SPECIFIC IMMUNITY – 1ST LINE Chemical Barriers • Animals • Interferons (triggered by pathogenic double stranded RNA not found in unaffected cells) • (other) cytokins (protein messengers) that can cause apoptosis and attract WBCs • Lactic acid • Lysozyme, an enzyme, intears, sweat, salica • Natural flora • Complement proteins • Plants • Secondary substances: antibiotics, proteases, cellulases and chitinases • Hormone ecdysone (causes insects to moult • toxins Physical Barriers • Animals • Skin (dry, hard keratin) • mucous secretions on membranes • Ciliated membranes (throat and lungs) • Lysosomes • Gastric acids • External hairs • Plants • Waxy cuticle • Cell wall • Plasma membrane • External hairs

  10. Skin An intact skin acts as a barrier against entry by micro-organisms. A cut or abrasion will allow entry of bacteria or viruses. Hardening of outer layers Provides a physical barrier Anti-bacterial and anti-fungal secretions Produced by sweat glands, sebaceous (oil) glands, bacterial flora of the skin Lack of moisture Limits growth of microorganisms CHP 8 TOPIC 3: NON-SPECIFIC IMMUNITY – 1ST LINE

  11. CHP 8 TOPIC 3: NON-SPECIFIC IMMUNITY – 1ST LINE Mucous Membranes • secreted by the cells lining your respiratory tract • traps bacteria which are then swept upwards to the back of the throat by the action of cilia. • some of the mucus and bacteria is then swallowed, coughed or sneezed out, or blown out through the nose. • promote growth of natural flora whose secretions limit pathogen growth

  12. CHP 8 TOPIC 3: NON-SPECIFIC IMMUNITY – 1ST LINE Natural Secretions • Many secretions of the body contain bactericidal agents. Tears and saliva contain lysozyme, an enzyme that cause bacteria to lyse or burst. Acid in the stomach also kills many bacteria. Peristalsis • Diarrhoea eliminates pathogens by movement towards the anus for elimination • Vomiting also results in removal of pathogens from body Chapter 8 - Defence Against Disease

  13. CHP 8 TOPIC 3: NON-SPECIFIC IMMUNITY – 1ST LINE Enzymes • Lysozyme in tears, saliva, sweat, nasal secretions and tissue fluids breaks up (lyses) the cell wall of certain bacteria Natural Flora • Many different bacteria are normally found on the skin, gut and in the vagina. These bacteria are harmless to the body and occur naturally. • The presence of these bacteria can inhibit the growth of pathogenic bacteria as they compete for nutrients and space.

  14. CHP 8 TOPIC 3: NON-SPECIFIC IMMUNITY – 1ST LINE Gastro-intestinal secretions • HCl in stomach, alkaline fluids e.g. bile in duodenum • Are of a pH which is outside the range of tolerance for many microorganisms • Many pathogens killed by stomach acids Hairs and cilia • Filter inhaled air • Remove micro-organisms and other antigenic material (e.g. pollen)

  15. Topic CHP 8.3 Questions: • List two physical barriers to infection in: • Plants: ______________________________, ________________________ • Animals: _____________________________, _______________________ • List two chemical barriers to infection in: • Plants: ______________________________, ________________________ • Animals: _____________________________, _______________________ • The hard surface of skin is a result of the protein called: _____________________ • The first layer of skin is called the : ____________________ • Tears and sailva contain ________________a bacterial agent

  16. Non-specific mechanisms:Non-Specific Cellular Defences: 2nd line of defence CHP 8 TOPIC 4: NON-SPECIFIC IMMUNITY – 2nd LINE

  17. CHP 8 TOPIC 4: NON-SPECIFIC IMMUNITY – 2nd LINE

  18. CHP 8 TOPIC 4: NON-SPECIFIC IMMUNITY – 2nd LINE CELLULAR … Monocytes • Largest of the white blood cells • become macrophages when they leave the bloodstream Macrophages • gather in various tissues such as the lungs, liver, kidneys and brain. • are particularly active against micro-organisms that can live inside the cells of the person they infect. • engulf bacterium Neutrophils • The most numerous of the phagocytotic cells • Granulated nucleus • Attacks bacteria • Die after engulfing bacterial pathogen • Their dead cells become the bulk of • ‘pus’ at wounds

  19. CHP 8 TOPIC 4: NON-SPECIFIC IMMUNITY – 2nd LINE Eosinophils • can be phagocytotic. • secrete enzymes to kill parasitic worms among other pathogens

  20. CHP 8 TOPIC 8.4: NON-SPECIFIC IMMUNITY – 2nd LINE Basophil - contain granules of toxic chemicals that can digest foreign microorganisms.  These are cells involved in an allergic response Mast Cells - similar to basophils, mast cells contain a variety of inflammatory chemicals including histamine and seratonin.  Cause blood vessels near wound to dilate! and increase permeability of the capillaries Basophils are a type of white blood cell (leukocyte). These cells help you fight infections by releasing histamine and other chemicals like heparin (antocoagulant)

  21. Natural killer cells (NK cells) are a type of lymphocyte (like macrophages) police the body in blood and lymph lyse and kill cancer cells and virus-infected cells act against any such target (i.e. non-specific) recognise certain sugars on invader’s surface are notphagocytic: attack membrane of target cell and cause it, and its nucleus, to disintegrate CHP 8 TOPIC 8.4: NON-SPECIFIC IMMUNITY – 2nd LINE

  22. CHP 8 TOPIC 8.4: NON-SPECIFIC IMMUNITY – 2nd LINE Platelets • cell fragments circulating in blood • also release histamine and involved in clotting of blood

  23. CHP 8 TOPIC 4: NON-SPECIFIC IMMUNITY – 2nd LINE

  24. Topic CHP 8.4Questions: 2nd Line of Defence Chapter 8 - Defence Against Disease

  25. CHP 8 TOPIC 5: THE INFLAMMATORY RESPONSE

  26. CHP 8 TOPIC 5: THE INFLAMMATORY RESPONSE Blood vessels dilate Increased blood flow to region Redness Heat Mast Cells Pathogens Enter Tissues Edema Capillaries become permeable and leaky Produce Histamine and seratonin etc Basophils Platelets Pus Phagocytes move to an area Complement Proteins Increased phagocytosis

  27. CHP 8 TOPIC 5: THE INFLAMMATORY RESPONSE

  28. CHP 8 TOPIC 5: FEVER - PYREXIA The Cause of Fever

  29. Topic CHP 8.5Questions: • True/ False: mast cells are only found in muscle cells • True/ False: mast cells produce histamines and seratonin • True/ False: platelets produce histamines • True/ False: phagocytes will attack any pathogens that are identified as ‘non self’ • True/ False: Edema is a build up of fluid within the circulatory system • What is the role of interleukin in the immune response: ________________________________________________________________________

  30. Specific Immunity 3nd Line of defence Once a pathogen or other foreign material has entered the body, it is not only bombarded with your non-specific defences but is subject to attack by cells of immune system, the T and B Lymphocytes. This system is slower to take action but is more specific in its attack.

  31. CHP 8 TOPIC 6: SPECIFIC IMMUNITY -INTRODUCTION

  32. CHP 8 TOPIC 6: SPECIFIC IMMUNITY -INTRODUCTION STEM CELLS Bone Marrow- specialise into blood cells Lymphocytes Develop in bone marrow NK Cells (see non-specific defences) Mature B Cells (see non-specific defences) Thymus processing Mature T Cells (see non-specific defences) Migrate to Lymph nodes Migrate to Lymph nodes Cytotoxic T Cells Memory B Cells Memory T Cells PlamsaB Cells Helper T Cells

  33. Topic CHP 8.6Questions: • Stem cells produce a variety of cells including erythrocytes and leucocytes: give 5 examples of cells that differentiate from stem cells: • _________________________ • _________________________ • _________________________ • _________________________ • _________________________ • _________________________ • Where do B cells mature? ____________ • What kind of cells produce antibodies: _________________

  34. Self and Non-self all cells have marker proteins on their plasma membrane these proteins are the products of the MHC genes. each person has different MHC genes (like a fingerprint). therefore marker proteins are specific to each person/organism cells with the body's own marker proteins are accepted as “self”. these proteins are not antigenic to our own immune system. cells with foreign markers are recognised as “non-self”. these marker proteins areantigenic for us. antigen receptors are also known as immunoglobulins (Ig) It is the binding of receptor (immunoglobulin and antigen that initiates an immune response class 1 markers found on all cells except rbc. class 2 – only on b, t cellsand some macrophages • CHP 8 TOPIC 7: SPECIFIC IMMUNITY -SELF AND NON-SELF How Does The Body Know What Cells To Attack

  35. Antigens the term “antigen” originates from “antibody generator” – triggers immune response defined as a substance that, when it invades the body, will stimulate the formation of a specific type of antibody usually protein or polysaccharide may be free e.g. in the bloodstream, or attached to the cell surface of a pathogen critical in differentiating “self” and “non-self” self antigens on the cell membranes are called “markers”. those markers critical to the success of transplantation form the mhc(major histocompatability complex) an antigen is typically a large complex molecule, not normally present in the body, that is capable of producing an immune response • CHP 8 TOPIC 7: SPECIFIC IMMUNITY -SELF AND NON-SELF

  36. CHP 8 TOPIC 7: SPECIFIC IMMUNITY -SELF AND NON-SELF Tolerance by the body's immune system to its own cells and tissues During development (maturation), body removes any cells immune cells that attack ‘self’ Self Tolerance

  37. CHP 8 TOPIC 7: SPECIFIC IMMUNITY -SELF AND NON-SELF Blood Groups – Blood Antigens Chapter 8 - Defence Against Disease

  38. CHP 8 TOPIC 7: SPECIFIC IMMUNITY -SELF AND NON-SELF Rhesus Incompatibility • A red blood cell antigen, the rhesus factor is present on the red blood cells of a majority of people. Such people are rhesus positive (RH+). If the antigen is absent a person is rhesus negative (Rh-). If a person who is Rh- and comes into contact with RH+ blood will respond by producing antibodies against the antigen. This can become critical in pregnancy

  39. CHP 8 TOPIC 7: SPECIFIC IMMUNITY -SELF AND NON-SELF Rhesus Incompatibility Chapter 8 - Defence Against Disease

  40. CHP 8 TOPIC 7: SPECIFIC IMMUNITY -SELF AND NON-SELF these occur when the immune system loses its ability to tolerate “self” antigens. the body produces “autoantibodies” and sensitised T cells that attack the body’s tissues. Autoimmune Diseases

  41. CHP 8 TOPIC 7: SPECIFIC IMMUNITY -SELF AND NON-SELF Multiple sclerosis: destroys the myelin sheath of the brain and spinal cord. Myasthenia gravis: which impairs the communication between nerves and the skeletal muscles Graves disease: the thyroid gland produces excessive amounts of thyroxine Juvenile (type 1) diabetes mellitus: destroys pancreatic beta cells, resulting in deficient insulin production Systematic lupus erythematosus, SLE : occurs in young females and affects the heart, kidneys, lungs and skin Glomerulonephritis: a severe impairment of kidney function Rheumatoid arthritis: which systematically destroys joints The most common autoimmune diseases

  42. CHP 8 TOPIC 7: SPECIFIC IMMUNITY -SELF AND NON-SELF Transplantation has mixed success because the immune system is ever vigilant. There are four types of grafts Autografts: tissue grafts from one site to another in the same person Isografts: tissue grafts from a genetically identical individual (an identical twin) Allografts: tissue grafts from an unrelated person Xenografts: tissue grafts from a different animal species e.g. pig or baboon. Organ Transplants and Rejection

  43. CHP 8 TOPIC 7: SPECIFIC IMMUNITY -SELF AND NON-SELF Autografts and isografts are ideal donor organs, and are almost always successful, given Adequate blood supply No infection Xenografts are never successful. Allografts are most commonly used. ABO and other blood group antigens must match Cell membrane antigens are typed, and at least a 75% match is needed to attempt a graft After surgery the patient receives immunosuppressive therapy Explosive bacterial and viral infection is the most frequent cause of death in these patients, since the immune system is compromised Organ Transplants and Rejection

  44. B & T Cells: A partnership CHP 8 TOPIC 9 B & T CELLS – SOLDIERS IN ARMS SPECIFIC IMMUNITY Cell Mediated Immunity – T Cells Humoral Immunity- B Cells (Antibody Mediated) antigen B Cell receptor (immunoglobuln) binds with antigen CLONAL SELECTION T Helper Cell binds with b cell Releases chemicals to attract phagocytes T Cells B Memory Cells Cytotoxic T Cells T Memory Cells B Plasma Cells

  45. Topic CHP 8.8Questions: • MHC = _________________________________________ • What kind of cells have Ig on their surface: ________________ & ____________ • Class 2 MHC markers are found on what kind of cells: ________________________ • An antigen is: _____________________________________________________________ _________________________________________________________________________ • A person with blood group A+ can donate blood to people with blood groups: ___________ & ____________ • A person with Blood group O + can receive blood from: _________________________ • B Cell proliferation is initiated by the presence of what two factors: ___________________ & __________________________ • Killer T cells are part of ______________ mediated response

  46. CHP 8 TOPICS 10 & 11: HUMORAL (Antibody mediated) IMMUNITY

  47. CHP 8 TOPIC 10: ANTIBODIES & IMMUNOGLOBULINS Antibodies- “immunoglobulins” • B-cells haveimmunoglobulinson their surfaces. • Immunoglobulins are proteins that identify antigens, (are antigen receptors). • Immunoglobulins are called antibodies when released from B Cells . • The immunoglobulins of each B-cell have a specific structure and recognise only one kind of antigen. • There are millions of antigens that the body must be able to respond. In response to this millions of different B-cells are produced with different immunoglobulins on their surfaces.

  48. CHP 8 TOPIC 10: ANTIBODIES & IMMUNOGLOBULINS The Structure of Antibodies Chapter 8 - Defence Against Disease

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