Chapter 17 The Lymphatic System and Immunity
Immunity Innate Immunity Fast, non-specific and no memory Barriers, ph extremes, Phagocytes & NK cells, fever, inflammation, complement, interferon Adaptive Immunity Slower, specific & has a memory Lymphocytes: T-cells & B-cells
Lymphatic System Lymphatic tissue Reticular connective tissue containing lymphocytes Bone marrow Lymph- interstitial fluid in lymphatic vessels Returns excess filtration from capillaries- to circulation Transport dietary lipids Maintenance & distribution- lymphoid organs Filter bacteria and help active defenses
Lymphatic System
Lymphatic Vessels Begin at lymphatic capillaries Slightly larger than blood capillaries Overlapping cells like one-way valve Pressure will force fluid in Merge to form larger & larger vessels Thin walled and more valves than veins Periodically have lymph nodes Lymphocytes in capsuled structure thoracic duct L subclavian vein At junction with jugular R. lymphatic duct R. subclavian vein
Lymphatic Vessels
Lymphatic Vessels
Lymphatic Flow From tissue to veins Pumped by muscle & respiratory pumps like venous return
Lymphatic Flow
Lymphatic Flow Interactions Animation Lymph Formation and Flow You must be connected to the internet to run this animation.
Lymphatic Organs Primary lymphatic organs- stem cells divide & develop into mature B & T-cells Red bone marrow & thymus Secondary organs: immune responses occur Lymph nodes, spleen & lymphatic nodules
Thymus Two lobed organ Posterior to sternum, medial to lungs & superior to heart T-cells divide & mature Self reactive cells are removed
Lymph Nodes Scattered throughout the body Concentrated near mammary glands, axilla & groin Contain mature B-cells, T-cells dendritic cells and macrophages Filter lymph, trap foreign substances Macrophages & lymphocytes destroy most foreign substances
Lymph Nodes
Spleen Between stomach & diaphragm Contains blood filled venous sinuses and RBCs, macrophages, lymphocytes plasma cells & granular leukocytes destroys worn or defective blood cells & platelets Stores platelets attacks foreign substances in blood Fetal hemopoiesis
Innate Immunity: Barriers Skin: physical and chemical Epidermal structure & constant shedding Mucous membranes Sticky mucus layer straps microbes, etc. and cilia move it out Fluids: tears, saliva, perspiration, nasal secretions Dilute and antibacterial action Movement: flow of urine, defecation & vomiting
Internal Defenses: Proteins Interferons Interfere with viral reproduction in a cell Complement System Enhance other immune actions Break cell membranes Attract phagocytes Tag microbial cells for destruction Transferrins- bind iron and starve bacteria Antimicrobial peptides: lyse microbes
Internal Defenses: Cells Phagocytes specialized to ingest microbes and cellular debris Neutrophils Monocytes macrophages 5-10% of lymphocytes = Natural Killer (NK) Cells Destroy microbes & tumor cells Present in lymph nodes & red bone marrow
Inflammation Response to tissue damage Indicated by redness, pain, heat & swelling
Inflammation 1. Damage mast cells, basophils & platelets release histamine increased permeability & vasodilation in blood vessels 2. Leakage of clotting proteins into tissue- Isolate bacteria behind clot 3. Phagocytes attracted to site Neutrophils & macrophages eat & die 4. Pocket of dead cells = pus Moves to body surface or into cavity & is cleared
Inflammation
Fever Abnormally high body temperature New set-point of thermoregulation system Normal temperature control action with new set point Stimulated by many toxins or internal signals Interleukin-1
Adaptive Immunity Specifically directed against a particular type of invader Involves cell or antibody directed against a particular antigen Antigen can be any substance: microbe, food, pollen, tissue Normally self tolerant Does not attack normal body tissue
Maturation of T and B cells From stem cells in red bone marrow B cells mature in bone marrow T cells migrate to thymus During maturation both make particular proteins in plasma membranes = antigen receptors
Types of Responses Cell-mediated- T-cells attack directly Killer T-cells Antibody-mediated B cells become plasma cells Produce specific antibodies Helper T cells aid both cell- and antibodymediated responses
Antigens & Antibodies Major Histocompatability Complex (MHC) = self antigens on cells surface Unique to each individual Allows T-cells to recognize foreign material Antigen triggers plasma cell to produce antibodies Y-shaped protein with variable antigen binding site on arms Other end triggers recognition by phagocyte
Antigens & Antibodies
Antigens & Antibodies
Triggering Adaptive Response Requires recognizing the foreign antigen B-ceils can find it anywhere T-cells need presentation with MHC Antigen presenting cells (APC) do this APCs macrophages, dendritic cells & B cells In respiratory, GI, urinary, reproductive tracts & lymph nodes
Processing & Presenting Antigens APC s ingest & digest into fragments in vesicles Synthesize MHC & pack in vesicles Two vesicles fuse Antigen fragments bind to MHC Antigen-MHC complex inserted into plasma membrane Presented to T-cells until a receptor matches & binds
Processing & Presenting Antigens
Cell Mediated Immunity T-ceils also need costimulator Interleukin-2 (IL-2) Binding both response T-cell begins rapidly dividing Forms a clone of many recognizing cells Helper T cells Release IL2, attract phagocytes, stimulate macrophages & B cells
Cell Mediated Immunity Cytotoxic T cells kill cells Work against tumor cells transplanted cells & infected cells Memory T cells- hang around for years, give rapid response
Cell Mediated Immunity
Cell Mediated Immunity
B-cells and Antibody-Mediated Response Hang out in lymph nodes Respond to antigen (faster if presented) With IL-2 enlarge, divide and become a clone of plasma cells Plasma cells produce & release antibodies that bind the antigen Some remain as Memory B Cells Ready to respond quickly if antigen met again
Secretion of Antibodies
Antibody Class Actions Neutralizing antigen Binds and neutralizes toxins Immobilizing bacteria Agglutinating Connect pathogens to one another easier phagocytosis Activating complement Enhancing phagocytosis Binding attracts phagocytes
Immunological Memory Long lasting antibodies & lymphocytes Many sensitive memory cells Much larger & quicker response next time = Secondary Response Primary response can be naturally acquired Or artificially acquired by vaccination Killed cells, isolated antigens, parts of viruses
Immunological Memory Interactions Animation Introduction to Disease Resistance You must be connected to the internet to run this animation.
Aging Thymus atrophies Fewer responsive T cells Thus poorer B cell response Poorer response to new infection
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