Circulatory system VI Flashcards
what does the lymphatic system consist of?
- lymph
- lymph vessel
- lymph ducts
- lymph nodes
- spleen and thymus
- lymphoid tissue (tonsils)
- bone marrow
what is lymph?
clear watery fluid which is in similar composition to plasma, contains lymphocytes which circulate in the lymphatic system
what is the function of lymph?
- carries away larger particles such as bacteria and cell debris from damaged cells
- which is then filtered out and destroyed by lymph nodes
describe lymph vessels structure?
- begin as blind ended capillaries
- single layer of endothelial cells
- permeable walls to allow all interstitial fluid components to pass through
what do lymph vessels form?
they get larger as they join together, forming 2 large ducts:
- thoracic duct
- right lymphatic duct
describe the structure of the thoracic duct?
- commences approx. in region of 2nd lumbar vertebrae
- about 40 cm long
- opens into left subclavian vein in root of neck
what is the drainage of the thoracic duct?
drains lymph from:
- both legs
- pelvic and abdominal cavity
- left side of thorax, arm, head & neck
describe the right lymphatic duct?
- 1 cm long
- lies in root of neck and enters right subclavian vein
what is the drainage for the right lymphatic duct?
drains from right side of head, neck, thorax and right arm
what are the functions of a lymph node?
- filtering & phagocytosis of bacteria and other toxins
describe the structure of a lymph node?
- mainly composed of reticular and lymphatic tissue containing lymphocytes and macrophages
how many afferent vessels enter a lymph node?
4 or 5
how many efferent vessels carry lymph away from the node?
1
where is the thymus situated?
internal surface of sternum up into neck
what happens when lymphocytes enter the thymus?
they become T-lymphocytes, which react to specific antigens
