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39 Cards in this Set
- Front
- Back
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What does the Lymphatic system to? |
Returns fluids that leaked from blood vessels back to blood and aid in body defenses |
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What are the three parts of the Lymphatic System |
1. Network of lymphatic vessels (lymphatics) 2. Lymph – fluid in vessels contain water,plasma protein, & ions 3. Lymph nodes –Small organs associated with lymphatic vessels which cleanse lymph |
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What direction does the lymph flow? |
It's a one-way system that flows to the heart |
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What is the composition of lymphatic capillaries? Where are they absent? |
•Similar to blood capillaries,except: –Very permeable(take up proteins, cell debris, pathogens, and cancer cells) –Pathogens travel throughout body via lymphatics Absent from bones, teeth, bone marrow and CNS |
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What are lacteals? What does it do? |
Specialized lymph capillaries present in intestinal mucosa. Function: absorb digested fat and deliver fatty lymph (chyle) to the blood |
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What are Lymphatic vessels? Where do they travel? |
Similar to veins,except they have thinner walls, with more internal valves –Anastomose more frequently Collecting vessels in skin travelwith superficial veins Deep vessels travel with arteries |
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How are Lymphatic Trunks formed? |
•Formed by union of largest collecting ducts |
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What are the two lymphatic ducts and where do they empty to? |
Right lymphatic duct drains right upperarm and right side of head and thorax Thoracic duct arises as cisterna chyli; drains rest of body •Each empties lymph into venouscirculation at junction of internal jugular and subclavian veins onits own side of body |
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Lymph Transport: Fill in the Blank •Lymph propelled by: ________ of skeletal muscle ________ in thorax during breathing ________ to prevent backflow ________ of nearby arteries ________ of smooth muscle in walls of lymphatics - |
Lymph propelled by: –Milking action of skeletal muscle –Pressure changes in thorax during breathing –Valves to prevent backflow –Pulsations of nearby arteries –Contractions of smooth muscle in walls of lymphatics |
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Where do lymphocytes arise and what are the two main varieties that they mature into? |
Lymphocytes arise in red bone marrow. mature into two types: T cells B cells |
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What do T cells and B cells do? |
T cells and B cells protect against antigens –Anything body perceives as foreign T cells –Manage immune response –Attack and destroy infected cells B cells –Produce plasma cells, which secrete antibodies |
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What do antibodies do? |
Antibodies mark antigens for destruction by phagocytosis or other means |
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What are the functions of the lymphoid cells below: Macrophages Dendritic cells Reticular cells |
•Macrophages phagocytize foreign substances; help activate T cells •Dendritic cells capture antigens and deliver them to lymph nodes •Reticular cells produce reticular fiber stroma that supports othercells in lymphoid organs |
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True or False: All leukocytes are lymphocytes, but not all lymphocytes are leukocytes |
FALSE True Statement: All lymphocytes are leukocytes, but not all leukocytes arelymphocytes |
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What do Lymphoid Tissues do? |
•Houses, and provides proliferation site for,lymphocytes •Furnish an ideal surveillance vantage point forlymphocytes and macrophages |
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What is the composition of Lymphoid Tissues? |
Largely reticular connective tissue - type of loose connective tissue Two main types: Diffuse lymphoid tissue and Lymphoid follicles |
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Where are Diffuse lymphoid tissues found? |
Diffuse lymphoid tissues are found in every body organ |
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Composition of lymphoid follicles |
•Lymphoidfollicles (nodules) are solid, sphericalbodies of tightly packed lymphoid cells and reticular fibers |
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What are Lymph Nodes |
Lymph nodes are the principal lymphoid organs of body found near the body service. Small organs are intimately associated with lymphatic vessels |
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What are the two functions of Lymph nodes? |
1.Filter lymph—macrophages destroy microorganisms and debris 2.Immune system activation—lymphocytes activated and mount attackagainst antigens |
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What is the structure of Lymph Nodes? |
•Vary in shape and size but most bean shaped •External fibrous capsule •Trabeculae extend inward and divide nodeinto compartments •Two histologically distinct regions: Cortex and Medulla Contain germinal centers (divide B cells) Dendritic cells nearly encapsulatefollicles Deep cortex contains T cells Medullary cords extend inward from cortex and contain B cells, T cells and plasma cells Lymph sinuses contain macrophages |
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Circulation in the Lymph Nodes: How do they travel? |
–Enters convex side via afferent lymphatic vessels; travels through large subcapsular sinus and smaller sinuses to medullary sinuses; exits concave side at hilum via efferent vessels |
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Circulation in the Lymph Nodes: Fewer _______ vessels so flow is somewhat _______; this allows _____ and _____ time to function |
Fewer efferent vessels so flowsomewhat stagnate; allows lymphocytes and macrophages time to function |
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The spleen is the ______ lymphoid organ What is it served by? |
Largest Served by splenic artery and vein, which enter andexit at the hilum |
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Main Functions of the Spleen |
–Site of lymphocyte proliferation and immune surveillance and response –Cleanses blood of aged cells and platelets, macrophages remove debris |
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Other functions of the spleen |
•Stores breakdown products ofRBCs (e.g., iron) for later reuse •Stores blood platelets and monocytes •Has a fibrous capsule and trabeculae •Contains lymphocytes,macrophages, and huge numbers of erythrocytes |
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Structure of Spleen |
Two distinct areas: –White pulp around central arteries •Mostlylymphocytes on reticular fibers; involved in immune functions –Red pulp in venous sinuses and splenic cords •Rich in RBCs and macrophages for disposal of worn-out RBCs and bloodborne pathogens |
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Where do you find the Thymus? |
Found in inferior neck; extends into mediastinum; partially overlies heart |
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Thymus: Fill in the Blank Increases in size and most active during ______ Stops growing during ________, then gradually atrophies ٜ |
•Increases in size and most active during childhood •Stops growing during adolescence, then gradually atrophies ٜ |
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Composition of Thymus |
Thymic lobules contain outer cortex andinner medulla Most thymic cells are lymphcytes Cortex: contains rapidlydividing lymphocytes and scattered macrophages Medulla: contains fewerlymphocytes and thymic (Hassall’s) corpuscles involved in regulatory T celldevelopment |
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How is the Thymus different from other lymphoid organs? |
- Has no follicles because it lacks B cells - Doesn't directly fight antigens; it functions strictly in T lymphocyte maturation |
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What is MALT? What is it's function? What is the location? |
Mucosa-Associated Lymphoid Tissue Lymphoid tissues in mucous membranes throughout body Function: Protects from pathogens trying toenter body Location: Largest collections of MALT in tonsils,Peyer's patches, appendix |
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Tonsils are the ______ lymphoid organ Where can they be found? What is the function? |
Simplest Location: Form ring of lymphatic tissuearound pharynx Function: Gather and remove pathogens infood or air |
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Tonsils: Fill in the blank _______ tonsils—at posterior end of oral cavity _______ tonsil—grouped at base of tongue _______ tonsil—in posterior wall of nasopharynx _______ tonsils—surrounding openings of auditorytubes into pharynx |
Palatine tonsils—at posterior end of oral cavity Lingual tonsil—grouped at base of tongue Pharyngeal tonsil—in posterior wall of nasopharynx Tubal tonsils—surrounding openings of auditory tubes into pharynx |
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NEED TO EDIT THIS •Contain follicles with germinalcenters•Are not fully encapsulated•Overlying epithelium invaginates forming tonsillar crypts–Trap and destroy bacteria and particulate matter –Allow immune cells to build memory for pathogens |
•Contain follicles with germinalcenters•Are not fully encapsulated•Overlying epithelium invaginates forming tonsillar crypts–Trap and destroy bacteria and particulate matter –Allow immune cells to build memory for pathogens |
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–Clusters of lymphoid follicles –In wall of distal portion of small intestine –Similar structures are also found in the appendix |
Peyer's Patches |
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–Destroy bacteria, preventing them from breaching intestinal wall –Generate "memory" lymphocytes |
Peyer's Patches and appendix |
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When do lympathic vessels develop? |
•Beginnings of lymphatic vesselsand main clusters of lymph nodes by 5th week ofembryonic development –Arise as lymph sacs from developing veins –Jugular lymph sacs arise -> right lymphatic duct and thoracic duct |
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When do Lymphatic organs develop? |
•Lymphoid organs (except thymus) develop from mesodermal mesenchymal cells •Except for spleen and tonsils, lymphoid organs poorly developed at birth |
