Lymphatic system Flashcards
What are the contents of the lymphatic system?
- Lymph
- Lymphatic vessels
- Lymphatic tissue
- Red bone marrow
What are the functions of the lymphatic system?
- Drainage of interstitial fluid (from high hydrostatic pressure in capillaries forcing out blood which needs to be collected)
- Transporting dietary lipids and lipid soluble vitamins (A,D,E,K)
- Facilitation of the immune response
Whats the process of the formation of lymph?
Structural relationship between capillary bed of blood vascular system and lymphatic capillaries (blood plasma that’s been pushed out)
1. Blood hydrostatic pressure pushes blood plasma out of the blood capillaries to bathe surrounding tissues
2. This blood plasma is now known as interstitial fluid
3. Blood protein Albumin too large to leave capillaries and creates osmotic pressure inside capillary
4. Blood osmotic pressure pulls interstitial fluid back into the blood capillaries
5. Not all interstitial fluid returns – it needs to be drained otherwise swelling occurs
6. Drainage occurs via lymphatic capillaries and lymph vessels
7. Lymphatic capillaries are blind ended – dead ends for one way movement
8. With lower pressure than interstitial fluid
9. Fluid enters lymph capillary via one way minivalves (stopping backflow back into blood vessels) once inside – this is known as lymph
Whats hydrostatic pressure?
Pushing force exerted by a fluid (30-10mmHg between arterial end and venous end)- from inside to outside the blood vessels
Whats interstitial fluid pressure?
Negative -3 mmHg contributing to outward pull of fluid from capillaries
Whats colloidal osmotic pressure?
Pulling force created by blood proteins that are too large to pass through the pores of the membrane (28 mmHg in capillaries) (the difference in protein concentration on inside and outside of blood vessels)
Whats interstitial osmotic pressure?
8 mmHg created by small number of plasma proteins that have leaked into extracellular tissue space
How is lymph drained?
- Lymph capillaries join together forming lymph vessels (eventually join back into blood vessels as drains into blood stream to maintain blood pressure)
- These are similar to veins and have valves
- Drain into two ducts in cardiovascular system
- right lymphatic duct
- left thoracic duct
What are the two ducts of the lymphatic system?
right lymphatic duct
left thoracic duct
Whats the right lymphatic duct?
- Drains upper right side of body and right arm
- Returns lymphatic duct returns lymph to right subclavian vein
Whats the left thoracic duct?
- Drains rest of body
- Begins with cisterna chyli and returns lymph to left subclavian vein
What are lacteals?
- In small intestines lymph capillaries are known as lacteals
- Lacteals carry fat laden lymph known as chyle
- Lacteals join together to form vessels
- These vessels containing fat laden lymph drain into cisterna chyli
Describe the relationship between cardiovascular and lymphatic system?
- Plasma form interstitial fluid
- This is returned to plasma
- Fluid not fully returned enters lymph capillary to form lymph
- This lymph is returned to cardiovascular system
Whats oedema?
- Palpable swelling produced by increased interstitial fluid volume
- Evident when interstitial fluid increases to 2.5 – 3L
What factors influence oedema?
- Increased capillary filtration pressure
- Decreased capillary colloidal osmotic pressure
- Increased capillary permeability
- Obstruction to lymph flow