BIOL 118 1st Edition Lecture 32Outline of Last Lecture I. Introduction to Animal ReproductionII. Asexual & Sexual ReproductionIII. Mechanisms of Sexual Reproduction: GametogenesisIV. Fertilization & Egg DevelopmentV. Role of Sex Hormones in Sexual ReproductionVI. Pregnancy & Birth In MammalsOutline of Current Lecture I. Introduction to the Immune System of AnimalsII. Innate Immunity & Adaptive ImmunityCurrent LectureIntroduction to the Immune System of Animals- All organisms are targets for diseases from pathogens, disease causing organismso Bacteria, parasites, viruses, fungi &protists- Immune system of the animal fights off the pathogens & keeps the animal healthy- Immunity: resistance to/protection against disease-causing pathogenso Prevents individuals from contracting a disease more than once- Immunization: conferring of immunity to a particular diseaseo Vaccination: introduction of a weakened or altered pathogen to prime the body’simmune system, so it fights later infections effectivelyInnate Immunity & Adaptive Immunity- Innate immunity: immune system cells that are ready to respond to foreign invaders at all timeso Is nonspecific & responds in the same way to all antigens Antigen: any foreign molecule that can initiate an immune response- Cells that require activation confer adaptive immunityo These cells respond in an extremely specific way to the particular strains of bacteria, viruses, or fungi that enter the body- Innate immune response: body’s nonspecific response to pathogens; involves leukocytes such as mast cells, macrophages These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Alerted to the presence of foreign invaders by antigens that are found on the surfaces of pathogens, but not on host cells o Steps: When skin breaks, pathogens enter a wound Platelets release blood-clotting proteins at the wound site Wounded tissues & macrophages at the wound site secrete chemokines: signaling molecules that recruit immune cells by forming a gradient to mark the path to the site Mast cells release chemical messengers that constrict blood vessels near the wound- reducing blood flow & thus blood loss- Also secrete histamine& other signaling molecules, which dilate blood vessels slightly farther away from the wound, making them more permeable Neutrophils & macrophages remove pathogens by phagocytosis: engulfing & digesting of foreign particles Macrophages secrete cytokines: chemicals that attract other immune system cells to the site & activate cells involved in tissue repair- Also induce fever: elevated body temperature that aids in healing- Adaptive immune response: based on interactions between specific immune system cells & a specific antigeno Antibodies: proteins produced & secreted by certain lymphocytes & bind to only a specific part of a specific antigeno Four key characteristics: Specificity: antibodies & other components of the adaptive immune system bind only to specific sites on specific antigens Diversity: adaptive response recognizes an almost limitless array of antigens Memory: can be reactivated quickly if it recognizes antigens from a previous infection Self-nonself recognition: molecules that are produced by an individual donot act as antigens, so the adaptive immune system can distinguish between self &nonselfo Lymphocytes: cells involved in adaptive immune response Produced in bone marrow: tissue that fills that cavities in bones Can also originate in spleen: lymphatic organ located in abdominal cavity B cells mature in bone marrow &T cells mature in the thymus Lymphocytes recognize antigens & become activated in the spleen &lymph nodes, small oval organs located throughout the body Circulate through the blood & the secondary organs of the immune system- lymph nodes, spleen & lymphatic ducts Lymphatic ducts: thin-walled, branching tubules that transport lymph throughout the body in the lymphatic systemSelf from Nonself, or Autoimmunity- If a B-cell receptor or T-cell receptor responded to a self molecule (molecule belonging to the host) the receptor would trigger an immune responseo Autoimmunity: anti-self reaction which can lead to self destruction To avoid, anti-self T & B cells are destroyed before they mature- Examples of autoimmunity:o Multiple sclerosis: results from the production of anti-self T cells that attack the myelin sheath of nerve fibers, resulting in muscular & coordination problemso Rheumatoid arthritis: develops when T cells & antibodies alter the lining of jointso Type 1 diabetes mellitus: occurs when T cells attack & kill insulin-secreting cells in the pancreas, resulting in an inability to regulate blood sugar
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