lymphatic system

lymphatic system

1. consists of:

   • • Lymphatic vessels
   • lymph
   • lymphatic tissue
   • red bone marrow

2. Lymphatic System - Functions

   • Drainage of interstitial fluid
   • Transporting dietary lipids and lipid soluble vitamins (A,D,E and K)
   • Facilitation of the immune response
   • Preventing the spread of cancer cells

3. Formation of Lymph

   • Blood hydrostatic pressure pushes blood plasma out of the blood capillaries to bathe the surrounding tissues
   • • The blood plasma is now known as interstitial fluid
   • The blood protein albumin is too large to leave the capillaries and creates an osmotic pressure inside the capillary
   • The blood osmotic pressure pulls interstitial fluid back into the blood capillaries • However not all of the interstitial fluid returns to plasma
   • This fluid needs to be drained or else swelling will occur • Drainage occurs via the lymphatic capillaries and lymph vessels
   • Structural relationship between a capillary bed of the blood vascular system and lymphatic capillaries
     • • Fluid enters the lymph capillary via one way mini-valves
     • • Lymphatic capillaries are “blind ended
     • • Internally they have a lower pressure than the interstitial fluid

4. Drainage of Lymph

   • Lymph capillaries join together to form lymph vessels
   • Lymph vessels have a similar structure to veins and have valves to ensure the one way flow of lymph
   • Lymph vessels drain into one of two ducts which return lymph to the blood
   • In the small intestine lymph capillaries are known as lacteals
     • Lacteals carry fat laden lymph known as chyle
       • The lacteals join together to form larger vessels
         • The vessels containing chyle drain into the cisterna chyli

5. Return of Lymph to Blood

   • The right lymphatic duct drains the upper right side of the body and right arm
   • The right lymphatic duct returns lymph to the right subclavian vein
   • The left thoracic duct drains the rest of the body
   • The left thoracic duct begins with the cisterna chyli and returns lymph to the left subclavian vein

6. Relationship between the CV and Lymphatic Systems - Summary

   • Plasma forms interstitial fluid
   • • Interstitial fluid is returned to the plasma
   • Fluid that is not returned to the plasma enters the lymph capillary to form lymph
   • Lymph is returned to the cardiovascular system

7. Lymphatic Organs and Tissues

   • In addition to those structures shown in the diagram below, there are also the Lymph Nodes
     • tonsils
     • thymus
     • spleen
     • peyers patches ( in intestines)
     • appendix
     • Lymph Nodes:
       • • Are found along the lymph vessels
       • • Are bean shaped structures that receive the lymph from afferent (entering) vessels
       • The lymph is then drained by efferent (leaving) vessels
       • Lymph nodes filter lymph

8. lymph nodes are

   • • Lymph nodes are surrounded by a connective tissue capsule
   • Trabeculae project inward from the capsule to form compartments
   • Each compartment or lobule is made up of a framework of reticular cells
   • • Reticular cells synthesise the reticular fibres
   • • Between the reticular cells are lymphocytes
   • • Lymphocytes produce antibodies