Tissue fluid does not contain redblood cells and bloodproteins because they are too big to leave
Fluid returns to the blood due to hydrostatic pressure pushing it back into the capillaries
Blood and fluid contain solutes giving them negative water potential
The water potential of tissue fluid is less negative than that of the blood, causing water to move back to the blood by osmosis down the potential gradient
At the venous end of the capillary, the blood has lost its hydrostatic pressure
The combined effect of hydrostatic pressure in the tissue fluid and the osmotic force of the plasma proteins pushes the fluid back to the capillary
Not all tissue fluid returns to capillaries; some is drained into the lymphatic system
The lymphatic system consists of vessels like capillaries that start in the tissues and drain excess fluid into larger vessels re-joining the blood system in the chest cavity
Lymph fluid is similar to tissue fluid and contains the same solutes
Lymph has less oxygen and fewer nutrients, more CO2, wastes from body cells, and fatty material absorbed from the intestines
The main difference between tissue fluid and lymph is that lymph contains lymphocytes, made in the lymph nodes
Lymph nodes filter bacteria and foreign material from lymph fluid, and lymphocytes engulf and destroy these bacteria and particles