Presentation on theme: "10.1 The Body’s Lines of Defence"— Presentation transcript:
110.1 The Body’s Lines of Defence David Vetter ( )Born with severe combined immunodeficiency (SCID)SCID is an X-linked disorder, and David’s mother was a carrierTen seconds after birth, David was placed in a plastic bubble
2David VetterDavid needed a germ-free environment, so he had to be inside his bubble for 12 yearsDoctors hoped to cure SCID using a bond marrow transplant
3The Bone Marrow Transplant October 21, 1983, David received a bone marrow transplant from his sister, KatherineThe marrow contained the Epstein-Barr virus that causes mononucleosis
4Medical EthicsWhile knowing that David would have to live life in a bubble, doctors encouraged his mother to go through with the pregnancy. Some people have said that in this situation, it would have been better to terminate the pregnancy.What do you think?
5What was gained?Doctors now know that SCID can be treated within three months of birth with bone marrow screened for pathogens
6The Three Lines of Defense The first and second lines of defense of the human body are nonspecific immune responsesThe third line of defense, you immune system, reacts in specialized ways for various invaders
7The First Line of Defense Mostly physicalSkin and mucous membranes protect your bodyAcidic secretions keep skin at pH of 3-5Skin has acidic secretions that inhibit the growth of microbesLysozyme, an antimicrobial enzyme, is secreted in tears, saliva, mucous and sweat.
8Respiratory and Digestive System The respiratory passage is lined with mucousCilia also lines the respiratory passageThere is mucous in the respiratory passage that traps invading microbes and other foreign debris with the cilia.Acids in the stomach and protein digesting enzymes destroy most of the invading microbes carried into the body with food.Immune System Overview: Goals
9The Second Line of Defense Mobilized if an invader resides inside the bodyLeukocytes (white blood cells), engulf invading microbes, or produce antibodiesUnlike red blood cells, white blood cells have a nucleus
10Leukocytesalso called white blood cells are large opaque blood cells that engulf invading microbes. They can also produce antibodies.They have a nucleus (so different from red blood cells)The size of the nucleus and the types of granules that can be found inside of them can be used to classify them into different classes of leukocytes.Granulocytes: have cytoplasmic granules and are made in the bone marrow.Agranulocytes: do not have a granular cytoplasm and are also made in the bone marrow, but then modified in the lymph nodes.
11PhagocytosisNon-specific defense mechanisms rely mainly on phagocytosisMonocytes migrate from the blood and into the tissuesMacrophages extend pseudopods that grip the invading microbe
13Neutrophils Attracted to chemical signals emitted by damage microbes Chemotaxis: A process where the neutrophils exit the capillaries and move toward the damaged tissueLysosomal enzymes digest the microbe and the leukocyteThe remaining fragments of protein, dead white blood cells and the digested microbes are called pus
14Physical InjuryTissue damage initiates a localized inflammatory responseIt is a nonspecific immune response that results in swelling, redness, heat, and pain.Pus and inflammation are signs that the second line of defence has been at work.
16System Wide DefenseInjured cells emit chemicals that stimulate the production of phagocytic white blood cells, red blood cells and lymphocytes from the bone marrow
17Fever is another example of the body’s response to infection. When you have infectious organisms in your body, neutrophils and macrophages digest the invaders and release chemicals into the bloodstreamWhen the chemicals reach the hypothalamus, they reset your body temperature to 40C in order to make it difficult for the bacteria to survive.