Week of notes- Lymphatic System & Immune System
Week of notes- Lymphatic System & Immune System Biol 2230-001
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This 57 page Class Notes was uploaded by Madeline Notetaker on Thursday February 25, 2016. The Class Notes belongs to Biol 2230-001 at Clemson University taught by Dr. John Cummings in Spring 2016. Since its upload, it has received 41 views. For similar materials see Human Anatomy & Physiology II in Biological Sciences at Clemson University.
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Date Created: 02/25/16
All exchanges between bloodstream and tissue have to go through interstitial space;lymphatic picks up fluids and returns them back to circulation. Lymphatic vessels Collect interstitial fluid Lymphoid tissues and organs Most are reticular connective tissue Organs like lymph nodes and spleen,tonsils Active cells provide immune function Lymph Fluid in lymphatic vessels Becomes part of plasma One-way flow toward heart Closed end circuit Smallest ones are called lymphatic capillaries Dead end capillaries Travels up until dumped into jugular veins near the heart Smallest vessels Formed by loosely overlapping endothelial cells 1 layer Very permeable pressure (when pressure higher ono outside,fluid flows in) “Mini valve” system Anchored by collagen filaments Found throughout entire body EXCEPT: Bones Teeth Nervous system Lymphatic capillaries of the intestines Site of digestion Large substances (like lipids) make it into lacteals Lymph here is called chyle Chyle is rich in fats compared to lymph other places Lymphatic capillaries Lead into Lymphatic collecting vessels Lymphatic collecting vessels Have 3 tunics (interna,media, externa) that are much thinner than vein tunics Also contain valves that prevent backflow (have more valves than veins Empty into lymphatic trunks Lymphatic trunks Collect from large regions of the body 5 major ones 1. Bronchomediastinal 1. Drains the middle of the thorax 2. Subclavian 1. Stuff coming out of upper limbs 3. Jugular 1. Stuff coming out of head 4. Lumbar 1. From lower trunk/extremities 5. Intestinal From abdominal cavity Lymphatic capillaries Lymphatic collecting vessels Lymphatic trunks Lymphatic ducts 2 larger structures Right lymphatic duct:drains head,upper arm,and thorax Thoracic lymphatic duct:drains rest of body Those 2 connect Valves Prevent backflow Muscular pump Activity of skeletal muscle pushes fluid Respiratory pump Low pressure when breathing moves fluid into cavity Arterial pumping Flow of blood through arteries can help Smooth muscle contraction Even though the tunica media with smooth muscle is thin,it still contracts Important in lymphatic trunks and thoracic duct Lymphocytes- All produced in red bone marrow Both involved in immune function Production is triggered by chemical secretions B cells:when encounter free floating cells,triggered to produce plasma that produces antibodies that attach to foreign cells to mark them to be destroyed T cells:directly attack and destroy foreign cells that have already invaded body cells and cause them to lyse Macrophages Monocytes that leave circulatory system Phagocytic cells Can activate t- lymphocytes Dendritic cells Also phagocytic Can also activate t- cells Reticular cells Produce stroma:a network that can hold other cells Proliferation site for lymphocytes Lymphocytes accumulate Made of reticular connective tissue except for in thymus Most are mesodermal in origin except for thymus Allows detection of infection or damage Lymph nodes Principal lymphatic organs of the body Have germinal centers with accumulation of lymphocytes Lymph passes through multiple nodes along a vessel Spleen Largest lymph organ Behind stomach Germinal components so allows for lymphocyte proliferation Site of blood cleansing Removes aged cells,defective cells,gets rid of platelets Recycles Lots of macrophages in spleen Produces red blood cells in an embryo (because they don’t have bone marrow to produce them) Thymus Active in embryos and newborns Functions to promote immunocompetency The ability to interact with something foreign Site where t-lymphocytes becomes immunocompetent Get specific receptors T onsils Gather and remove pathogens that are entering our body from food or air Found in oral and nasal cavities Peyer’s patches In distal part of small intestine Destroy bacteria in intestines Help produce memory cells Lymph enters via afferent lymphatic vessels (3) Bring lymph to node Filters through sinuses Past germinal centers, medulla Exits through efferent lymphatic vessels (2) at hilus Blood delivered via splenic artery Lymph filtered by lymphocytes in white pulp Fluid get pushed through white pulp Then filtered by marcophages in red pulp Red pulp surrounds white pulp Cleansed fluid returns to splenic vein to return to circulation Action most prominent in newborns Secretes thymosin and thymopoietin CausesT lymphocytes to become immunocompetent Palatine tonsils Largest At base of tongue,on each side of oral cavity Most likely to be infected and removed Lingual tonsils Under tongue Pharyngeal tonsil (adenoids) Single structure Posterior wall of nasal cavity Aka adenoids Tubal tonsils Surround Eustachian tube Follicles with germinal centers Crypts Dead end alleys that liquid or air gets in Crypts trap bacteria and particulates Bacteria pass through epithelium into lymphoid tissue Lymphoid tissue destroys pathogens Memory cells formed in case we encounter again Isolated clusters of lymphoid follicles Destroy bacteria in small intestine Generate memory lymphocytes Developing veins bud off lymph sacs at fifth week post conception First to form are jugular lymph sacs Connection to circularity system Also from vena cava and iliac veins These form branching system of lymphatic vessels Starts big and branches off Connection of jugular lymph sac with jugular veins become right lymphatic duct and thoracic duct Lymphoid organs develop from mesodermal mesenchyme that become reticular tissue and then migrate to different parts of body Except thymus which in endodermal in origin;outgrowth of pharynx Thymus is actually the first lymphatic organ to form and starts to accumulate lymphocytes before birth IMMUNE SYSTEM Not a normal organ system;instead it’s a functional system working to bring about a response:immunity 1. Prevents the entry of pathogens into body 2. Prevents spread of pathogens IMMUNE SYSTEMS Nonspecific immune system Attacks anything foreign (all substances) Aka innate immune system External body membranes Includes inflammatory response IMMUNE SYSTEMS Specific immune system Aka adaptive immune system Has individual cells that will only respond to certain substances Lymphocytes Ex: SUPERFICIAL NONSPECIFIC DEFENSES Skin Unbroken epidermis is a barrier Epidermal tissue does not have blood supply SUPERFICIAL NONSPECIFIC DEFENSES Mucous membranes Line all internal body cavities Create a physical barrier Also secrete mucus that can act like a trap Secretions that make an acidic environment Protein digesting enzymes Lysozyme INTERNAL NONSPECIFIC DEFENSES Phagocytes Macrophages Monocytes that have escaped circulation Neutrophils Can perform phagocytic functions once binds to foreign cells Eosinophils Attack internal parasitic worms INTERNAL NONSPECIFIC DEFENSES Mast cells Somewhat phagocytic but not really Has specific receptors on it,but is nonspecific because can bind to many things Once bound,ingests and kills them Mostly bacteria INTERNAL NONSPECIFIC DEFENSES Natural killer cells NK cells Not phagocytic,instead it lyses Attacks cancerous cells in body or cells that have been infected by virus Nonspecific because goes after anything that is not normal Another class of lymphocyte Circulate in bloodstream INTERNAL NONSPECIFIC DEFENSES Inflammation Symptoms: Redness- because more blood there due to dilation Swelling- because fluids have leaked out of capillaries Heat- because blood carries heat Pain- fluids put pressure on pain receptors Result of dilation of capillaries Causes more cells (in blood) to be delivered to area and keep foreign things from spreading INTERNAL NONSPECIFIC DEFENSES Antimicrobial proteins A protein that attacks microorganisms or interferes with their reproduction 2 examples: Interferon Chemical secreted by a cell infected with virus that protects neighboring cells Complement system More than 20 proteins that function in complement Blood proteins that promote inflammation when activated INTERNAL NONSPECIFIC DEFENSES Fever Elevation of entire body temperature Systemic response Interferes with replication of cells PHAGOCYTIC MECHANISM Phagocyte recognizes pathogen’s carbohydrate surface markers Our own cells have markers (called MHC markers),so anything different than that is recognized as foreign Enhanced via opsonization Antibodies attaching making it easier to identify Cytoplasmic extensions adhere to pathogen Called adherence Pathogen pulled inside cell in vacuole Called phagosome Lysosome binds with phagosome forming phagolysosome Lysosomal enzymes digest pathogen Can be aided by respiratory burst (the secretion of additional breakdown chemicals) Residual body formed and then expelled to be filtered NA TURAL KILLER MECHANISM NK cells detect infected or cancerous body cells through lack of“self” markers or presence of certain sugars Some abnormality on cell NK cells release perforins:a type of cytolytic protein that lyses cells by making holes in plasma membrane Channels appear in target cells and nucleus disintegrates Destroys cell INFLAMMA TOR Y MECHANISM Toll-like receptors (TLRs ) on macrophages recognize pathogens TLRs release cytokines (cell chemicals) Cytokines promote inflammation- tells capillary to dilate Chemical attractants- attractWBC to accumulate Other cells release other inflammatory mediator chemicals Like histamine,prostaglandins… Vessels in injured area dilate and increase permeability Hyperemia occurs as result of dilation hyperemia=excess blood Exudate accumulates causing edema (swelling) that leavesfluid with antibodies and clotting factors Edema dilutes foreign substances and brings oxygen and nutrients to area RESUL TS OF INFLAMMA TION Injured cells release leukocytosis-inducing factors Causes neutrophil release by red bone marrow Now we have a higher number of neutrophils in blood= “leukocytosis” RESUL TS OF INFLAMMA TION Loss of fluids slows blood flow locally RESUL TS OF INFLAMMA TION Inflammation causes production of selectins on endothelial cells neutrophilsind to Margination occurs Holding neutrophils at the wall of capillary at site of damage Neutrophils escape capillaries RESUL TS OF INFLAMMA TION Inflammatory chemicals act as chemotactic agents monocytes to areals and Monocytes follow neutrophils Monocytes become macrophages after leaving capillaries lysosomes than monocytes INTERFERON MECHANISM Cells infected by virus release interferon (IFN) IFNs diffuse to nearby cells Cause them to produce PKR protein PKR protein synthesis is stimulated PKR interferes with viral replication IFNs also activate macrophages and NK cells COMPLEMENT SYSTEM MECHANISM I Antibodies bind to pathogens Complement proteins bind to antibody- pathogen complexes Lysis,phagocytosis and inflammation result COMPLEMENT SYSTEM MECHANISM II Complement proteins bind directly to polysaccharide molecules on pathogens Lysis,phagocytosis and inflammation result FEVER MECHANISM Leukocytes and macrophages exposed to pathogens secrete pyrogens Pyrogens cause hypothalamus to raise body temp An increase in body temp causes less iron and zinc to be available Pyrogens elevate metabolic activity Another way to get heat is shivering ANTIGEN =Any substance that produces immune response;anything foreign ANTIGENIC PROPER TIES Immunogenicity Reactivity An antigen is reactive Antigenic determinants The components **The antigenic determinants are the reactive parts that give it immunogenicity MAJOR HISTOCOMPA TIBILITY COMPLEX Self antigens MHC Are not immunogenic to ourselves,but would be immunogenic to someone else CHARACTERISTICS OF SPECIFIC IMMUNITY Pathogen specific Each cell that we have will only interact with a certain foreign cell Not immediately active There is a time delay Systemic Not localized to one spot Provides“memory” Activation of specific immune cells causes production of more of those cells to that can interact with the antigen faster the next time it encounters PA THWA YS Humoral Interacting with antigens that are free floating in blood stream “Antibody mediated pathway” Antibodies do not kill antigen directly,just mark kill (complement protein or phagocytic cells) Uses B lymphocytes PA THWA YS Cell-mediated Our body cell has become infected and is attacked Kills it directly through cell lysis UsesT lymphocytes L YMPHOCYTE PRODUCTION All are produced by stem cells in red bone marrow Immature ones are identical until they mature L YMPHOCYTE PRODUCTION Produced by stem cells in red bone marrow T cells become immunocompetent in thymus Acquire receptors on surface to interact with specific antigens B cells become immunocompetent in bone marrow
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