Ch 22 Sept. 26&28th Notes
Ch 22 Sept. 26&28th Notes BIOL 2402
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This 11 page Class Notes was uploaded by Madison Corkran on Thursday September 29, 2016. The Class Notes belongs to BIOL 2402 at Lamar University taught by James Armacost in Fall 2016. Since its upload, it has received 71 views. For similar materials see Anatomy and Physiology II in Biology at Lamar University.
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Date Created: 09/29/16
Exam 2 – A&P Lecture: Week 6 9/20/16 8:33 PM Ch.22 Lymphatic System • Fluid – Lymph • Tubes – Lymphatic Vessels • Pump- Nothing equivalent to hear t Is the Lymphatic system a high or low pressure system and why? • The lymphatic system is low pressure because the pump system used, is in no comparison to the cardiovascular system. Functions of the Lymphatic System • Homeostasis o Drains excess interstitial fluid • Transportation o Dietary lipids & lipd-soluables vitiamins • Immune Response o Roles in innate immunity & (especially) adaptive immunity Lymphatic tissue & fluid • Lymphatic tissues are connective tissues o Like blood • Lymphatic fluid (lymph) o Is essentially the same as interstitial fluid o Contains many lymphocytes (a type of WBC’s) Anatomy of Lymphatic systems • Lymph vessels o Lymphatic capillaries o Lymphatic vessels o Lymphatic trunks o Lymphatic ducts o Lymphatic organs and trunks Formation of lymphatic fluid • Some components of blood plasma leave capillaries of circulatory system to become intestinal tissue in body tissues o Excess interstitial fluid enters lymphatic capillaries … Movement of Lymph • Blood capillaries • Interstial fluid • Lymphatic capillaries • Lyphatic vessels • Lymphatic trunks • Lymphatic ducts • Vena cava Lymphatic capillaries • Lymohatic capillaries associated with capillary beds of circulatory system o Closed at one end o Merge together to form lymphatic vessels Lymphatic vessels • Similar to veins • Posses many valves to prevent backflow • Associated with lymph nodes • Pressure for movement of lymph generated by skeletal muscle and respatory pump • Lymphatic vessels merge into 5 lymph trunks Lymph Trunks & Lymph Ducts • 5 lymph trunks merge into 2 lymph ducts • lymph ducts return lymph to blood at vena cava Transport of dietary lipids • Lacteals o Specialized lymphatic capillaries in the small intestine o Absorb lipid molecules from diet that are too large to enter blood capillaries o Lipids travel through lymphatic system before entering blood Lymphatic organs and tissues • Primary lymphatic organs o Sites where stem cells give rise to mature, immunocompent cells o Red bone marrow, thymus • Secondary lymphatic organs & tissues o Sites where most immune responses occur o Lymph nodes and spleen Red Bone Marrow • Pluripotent stem cells in red blood marrow give rise to immunocompetent B cells & Pre T-cells • B cells migrate directly to blood or lymph nodes • Pre T cells migrate to thymus to finish maturation Thymus • Between sternum and aorta • Left and right lobes • Lobes divided into lobules o Each lobules has 2 layers § Cortex § Medulla Cortex of thymus • Pre T cells go through maturation process • Most die via apoptosis • Some migrate to medulla – some continue maturation Medulla of thymus • T cells complete maturation and migrate through blood, lymph nodes, spleen Lymph nodes • About 600 along lymphatic vessel • Often in groups • Filter lymph as it passes through nodes • Microphages and lymphocytes destroy pathogens Layers within the lymph node • Outer cortex • Internal cortex • Medulla Lymph nodes • Outer cortex o Includes masses of B cells o These masses are called lymphatic nodules o B cells can proliferate & become antibody producing plasma cells and memory B cells Immunity • Ability of body to ward off disease and damage • The opposite of susceptibility • Two types of immunity o Innate Immunity § Present at birth § Nonspecific o Adaptive immunity § Develops after exposure to particular pathogen § Specific Innate Immunity • Immediate but general defenses o External and internal • External defenses include o Physical and chemical barriers of the skin and mucous membranes o Also saliva, gastric juices, vaginal secretions, ect. Innate Immunity • Internal defenses include o Antimicrobial proteins o Natural Killer (NK) Cells o Phagocytes o Inflammation o Fever Antimicrobial Proteins • Found in blood plasma and in interstitial fluid • Include o Interferons (INFs) § Produced by a cell that has been invaded by a virus § Migrate to neighboring, uninfected cells § Induce synthesis of antiviral proteins in uninfected cells o Transferrins § Inhibit some microbes by limiting availability of iron o Complement System § Assist in processes of inflammation and immune response Natural Killer (NK) Cells • A type of lymphocyte • Found in blood, spleen, lymph nodes and red bone marrow • Bind to bacteria, cells infected by viruses, or cancer cells and release perforins that destroy target sale Phagocytes • Includes neutrophils, eosinophils, and macrophages (= mature monocytes) • Engulf microbes (phagocytosis) Stages of Phagocytosis • Chemotaxis o Phagocyte migrate to sites of infectionin response to chemical signal • Adherence o Phagocyte binds to microbe • Ingestion o Phagocyte extends to pseudopodia to engulf microbe • Digestion o Phagocyte releases lysaomes and other proteins to destroy Inflammation • Symptoms o Redness o Pain o Heat o Swelling o Loss of function • Localized response Inflammation • Functions of inflammation o Kills microbes o Prevents them from spreading to other tissues o Prepares the site for tissue repair Stages of inflammation 01. Vasodilation and increase permeability of capillaries i. Allows antibodies and clotting factors to enter tissue from blood plasma ii. Blood clotting can occur within interstitial fluid of tissue 1. Fibrin thread trap microbes, preventing their spread 02. Emigration of phagocytes i. Neutrophils and macrophages 03. Tissue repair Fever • Symptom o Increased body temperature • Functions o Increased reaction rates and interferon o Increased reaction rates of tissue repair mechanisms o Inhibits growth of some microbes Adaptive Immunity • A response to a specific antigen • Antigens o Foreign substances that provoke an immune response § Virus, bacteria, parasites, toxins, foreign tissue § Typically, the antigen is a protein molecule on surface of the pathogen or parasite Adaptive Immunity • Specifically o Targeting particular antigens o Distinguishing self from no self • Memory o Secondary exposure to previously encountered antigen provokes rapid, strong response Types of adaptive immune responses • Cell-mediated immune responses o Involves T cells (mature Thymus cells) • Antibody-mediated immune response o Involves B cells (mature in red Bone marrow) Cell-mediated immune response • Involves T cells o Leave lymphatic tissue o Mature into helper T cells and cytotoxic T cells o Destroy pathogens (or infected cells) directly • Targets include o Intercellular pathogens (viruses, bacteria, fungi inside host cells) o Cancer cells o Foreign Tissue Antibody- mediated immune response • Involves B cells, which o Remain in lymphatic tissue o Mature into plasma cells o Release antibodies o Antibodies leave lymphatic tissues destroy pathogens • Targets include o Antigens in body fluids o Extracellular pathogens (in body fluids outside cells) Antigens • Two characteristics of antigens o Immunogenicity § Ability to provoke an immune response § Production of antibodies by B Cells or proliferation of T cells o Reactivity § Ability to react with antibodies or cell it provokes Chemical nature of antigens • Typically large molecules • Most often proteins • Often on the surfaces of cells (in plasma membrane) • Often only in a small region ( the epitope) of a molecule triggers the immune response Antigen receptors • Molecules in the plasma membrane of T cells and B cells that recognize (bind to ) specific organs • Problem – incredible diversity of antigens in the environment o The human immune system has > 1billion antigen receptors o Each recognizes a specific epitope Diversity of antigens and antigen receptors • Specific gene segments code for different antigen receptors o There are about 35,000 human genes o Many fewer genes than antigens • Genetic recombination shuffles gene segments to create a huge number of unique combinations of gene segments Major histocompatibility complex (MHC) antigens • The immune system must be able to recognize our own body cells • MHC antigens occur in the plasma membranes of somatic cells (except RBC’s) • Every individual has a unique combinations og MHC antigens • T and B cells ignore self MHC antigens
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