Flashcards
Lymphatic System
Cards in this deck (17)
- 1Lymphatic System OverviewConsists of 2 part
• lymphatic vessels
• lymphoid tissue & organs - 2Lymphatic system functions• transports tissue fluid (lymph) back to the blood
• Play essential roles in body defence & resistance to disease - 3Tissue FluidTissue Fluid
Capillary beds – fluid forced out of blood
Most reabsorbed
Fluid left in tissues (approx 3L daily) = Tissue (Interstitial) Fluid (IF)
IF plus leaked plasma protein enters lymph capillary
Now called LYMPH – returned to blood Accumulated fluid = (O)EDEMA) - 4Lymph CapillariesBegin as blind ended tubes
Easily opened flap like mini valves
Throughout body
Absent in bone and teeth, bone marrow and the entire CNS
Inflamed tissue more permeable allows pathogens, cell debris and cancer cells enter lymphatic system - 5Collecting Vessels Structure and Function• Have the same three tunics as veins
• Have thinner walls, with more
internal valves
• Collecting vessels in the skin travel with superficial veins
• Deep vessels travel with arteries - 6Collecting vessels - continued• Lymphatic collecting vessels
• Collects lymph from lymph capillaries
• Carries lymph to and away from lymph nodes
• Returns fluid to circulatory veins near the heart - 7Lymphatic Vessels1. Lymphatic capillaries
2. Collective vessels
3. Lymphatic trunks – 5 major trunks
4. Collecting ducts – i) Right lymphatic duct
ii) Thoracic duct
5. Subclavian vein - 8Function of Lymphatic Vessels• Return excess tissue fluid to blood
• Return leaked protein to the blood
• Carry absorbed fat from intestine to the blood
• All returned to circulatory veins near the heart - 9Lymph TransportProperties of lymphatic vessels
• One way system toward the heart
• Valves
• No pump
• Lymph moves toward the heart - 10Mechanisms of Lymphatic Flow1. Skeletal muscle pump
2. Respiratory pump
3. Smooth muscle in the walls of the larger lymphatic vessels
4. Squeezing of the lymphatic vessels by the expansion/recoil of arteries that are wrapped in the same connective tissue sheath - 11Structure of Lymph Nodes• Vary in size and shape - most bean
shaped
• More afferent vessels enter node than
efferent vessel leaving at the hilus
• Capsule – fibrous strands - called trabeculae -extend inwards & divide into compartment - 12Structure of Lymph NodesCortex (outer part of node)
• Follicles = collection of lymphocytes (B & T)
• Germinal centres = B cell replication to produce plasma cells and antibodies
• Cells in transit – e.g. T cells.
Medulla = cords and sinuses (central) • contains phagocytic macrophages
 - 13Functions of Lymph Nodes• Filter lymph before it is returned to the blood
• Slow flow through lymph node to allow time for antigen removal & protection
• Defense cells within lymph nodes
– macrophages – engulf and destroy foreign substances (antigens)
– lymphocytes (B & T cells) – provide immune response to antigens - 14Spleen• Largest lymphoid organ
• Destroys worn RBCs & sends break down products to liver
• Site for lymphocyte proliferation, immune surveillance & response
• Filters & cleanses blood of microbes
• RBC production in fetus
• Stores platelets
• Blood reservoir - 15Thymus• Important in early
life
• Immunocompetence of T cells - 16Tonsils/Adenoids• Trap and remove antigens entering the pharynx in food or air.
- 17Peyer’s Patches• Wall of the small intestine
• Destroy bacteria – prevent entry into abdominal space
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- 5 HAP 1 Flashcards on Lymphatic System, created by Jonathan Cash on 16/10/2015.
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- Jonathan Cash
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