The Lymphatic System
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This 0 page Class Notes was uploaded by Brook Gaskill on Saturday February 6, 2016. The Class Notes belongs to BIOL 10212 at Rowan University taught by Steven J. Oxler in Spring 2016. Since its upload, it has received 11 views.
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Date Created: 02/06/16
Chapter 22 The Lymphatic System and Immunity The Lymphatic System A system consisting of lymphatic vessels through which a clear uid lymph passes The major functions of the lymphatic system include 0 O O Draining interstitial uid Transporting dietary lipids absorbed by the gastrointestinal tract to the blood Facilitating the immune responses Components of the lymphatic system include 0 000000 Lymphatic capillaries Lymphatic vessels Lymphatic nodes Lymphatic trunks Lymphatic ducts Primary lymphatic organs Secondary lymphatic organs and tissues Lymphatic Vessels and Fluid Lymph is a clear to milky uid in the extracellular uid compartment Extracellular uids include 0 O 0 Plasma the liquid component of blood Interstitial uid the clear uid filtered through capillary walls when it enters the interstitium space between cells also called the intracellular space Lymphatic uid the unaltered interstitial uid that enters the lymphatic vessels The ow of lymph uid is always from periphery towards the central vasculature 0000 0 It starts as interstitial uid Then enters lymphatic capillaries It travels in lymphatic vessels to the regional lymph nodes Lymph ascends or descends to the thorax either to the left or right lymphatic duct Lymph uid s final destination is in the bloodstream as it enters through the Subclavian veins Lymphatic capillaries are slightly larger than blood capillaries and have a unique oneway structure There are specialized lymphatic capillaries called lacteals that take up dietary lipids in the small intestine O Chyle is the name of this lymph with lipids Lymphatic uid is moved by pressure in the interstitial space and the milking action of skeletal muscle contractions and respiratory movements 0 An obstruction or malfunction of lymph ow leads to edema from uid accumulation in interstitial spaces Lymphatic Organs I The lymphatic system is composed of a number of primary and secondary organs and tissues widely distributed throughout the body 0 All with the purpose of facilitating the immune response 0 Primary lymph organs are the bone marrow and thymus I Secondary lymphatic organs are sites where most immune responses occur including the spleen and lymph nodes and other lymphoid tissues such as the tonsils I Thymus O The outer cortex is composed of a large number of immature T cells which migrate from their birthplace in red bone marrow 0 The inner medulla is composed of more mature T cells 0 The thymus slightly protrudes from the mediastinum into the lower neck I There are about 600 lymph nodes scattered along lymphatic vessels that serve as filters to trap ad destroy foreign objects in lymph uid 0 Important group of regional lymph nodes include I Submandibular I Cervical I Axillary I Mediastinal I Inguinal I The spleen is the body s largest mass of lymphatic tissue The Immune Response I Our immune response includes innate and adaptive responses I I IMMU N ITY lININATE ADAPTIVE inborn Acquired CEH MEDIATED 1 ANTIBODY MEDIATEID Innate Immunity I The innate immune response is present at birth It is nonspecific and non adaptive 0 It includes our first line of external physical and chemical barriers provided by the skin and mucous membranes 0 Our nonspecific innate immune response also includes various internal defenses 0 Internal defenses 0 Phagocytes Natural killer cells NK Endogenous antimicrobials Complement system Ironbinding proteins 0 Interferon O O O O I Phagocytosis is a nonspecific process Where neutrophils and macrophages from monocytes migrate to an infected area 0 Fever is an abnormally high body temperature due to resetting of the hypothalamic thermostat O Nonspecific response I Speeds up body reactions I Increases the effects of endogenous antimicrobials I Sequesters nutrients from microbes 0 In ammation is a defensive response of almost all body tissues to damage of any kind infection burns cuts etc 0 The four characteristic signs and symptoms of in ammation are redness pain heat and swelling 0 The in ammatory response has three basic stages 0 Vasodilation and increased permeability 0 Emigration movement of phagocytes from the blood into the interstitial space and then to site of damage 0 Tissue repair I Vasodilation allows more blood to ow to the damaged area Which helps remove toxins and debris 0 Emigration of phagocytes depends on chemotaXis O Neutrophils predominate in early stages but die off quickly 0 Monocytes transform into macrophages and become more potent phagocytes than neutrophils I Pus is a mass of dead phagocytes and damaged tissue I Pus formation occurs in more in ammatory responses and usually continues until infection subsides 0 Edema results from increased permeability of blood vessels 0 Pain is a prime symptom Which results from sensitization of nerve endings by the in ammatory chemicals Adaptive Immunity I Substances recognized as foreign that provoke an immune response are called antigens 0 Adaptive immunity describes the ability of the body to adapt defenses against the antigens of specific bacteria viruses foreign tissues 0 Two properties distinguish between adaptive immunity and innate immunity 0 Specificity for foreign molecules which act as Ag 0 Memory for previously encountered Ag 0 Molecules or parts of molecules tend to be antigenic if they are 0 Foreign not ourselves 0 Organic 0 Structurally complex proteins are usually complex and form many of the most potent antigents 0 Large high molecular weight 0 Antigens can have multiple antigenic determinants called epitopes 0 Antigenpresenting cells APCs are mostly dendritic cells and macrophages and they link the innate immune system and the adaptive immune system 0 Dendritic cells are usually found in tissues in contact with the external environment and they are the most potent of the antigenpresenting cell types 0 Once stimulated by antigen presentation helper T cells become activated 0 Activated helper T cells are capable of activating other lymphocytes to become T cytotoxic cells CD8 cells which directly kill foreign invaders and B cells 0 B cells can be activated by direct recognition of antigen through Bcell receptors or through Thelper cell activation Clonal Selection 0 Clonal selection is the process by which a lymphocyte proliferates and differentiates in response to a specific antigen 0 Lymphocytes undergo clonal selection to produce 0 Effector cells the active helper T cells active cytotoxic T cells and plasma that die after the immune response 0 Memory cells that do not participate in the initial immune response but are able to respond to a subsequent exposureproliferating and differentiating into more effector and memory cells Cytokines 0 Cytokines are chemical signals from one cell that in uences another cell 0 The are small protein hormones that control cell growth and differentiation 0 Interferon O Interleukins O Erythropoietin 0 Tumor necrosis factor Antibodies 0 Antibodies also called immunoglobulin or Igs are produced by plasma cells through antibodymediated immunity 0 The variable region gives an antibody its specificity 0 The stem is similar for each class of antibody I Some of the ways antibodies are effective include 0 Neutralizing a bacterial or viral antibody or a toxin by covering the binding sites and causing agglutination and precipitation O Activating the classical complement pathway 0 Enhancing phagocytosis a process called opsonization I The complement system is a series of blood proteins that often work in conjunction with antibodies it can be activated by multiple pathways in a step wise or cascading fashion 0 There are 5 classes of antibodies 0 IgG a monomer with two antigenbinding sites I Comprises 80 of total antibody I Only class able to cross the placenta I Provides longterm immunity 0 IgMa pentamer with ten antigenbinding sites I It is a great activator of complement but has a shortlived response I It is the first antibody to appear in an immune response 0 IgAa dimer with four antigenbinding sites I Prevalent in body secretions like sweat tears saliva breast milk and gastrointestinal uids 0 IgE a monomer involved in allergic reactions I Comprises less than 1 of total antibody in the blood 0 IgD a monomer with a wide array of functions some of which have been a puzzle since its discovery in 1964 Gaining Immunocompetence 0 Natural Immunity is not gained through the tools of modern medicine 0 Active Immunity refers to the body s response to make antibody after exposure to a pathogen antigen 0 In Passive Immunity the body simply receives antibodies that have been preformed 0 Active immunity is longterm passive is short term 0 Examples 0 Natural active contracting hepatitis A and production of antihepatitis A antibodies 0 Natural passive a baby receives antibodies from its mother through the placenta and breast milk 0 Artificial active a person receives a vaccine of an attenuated pathogen that stimulates the body to form an antibody 0 Artificial passive an injection of prepared antibody
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