Final answer:
Interstitial fluid provides nutrients to cells and removes waste products. It has various substances for cellular function and also aids the immune system by transporting antibodies and white blood cells. The lymphatic system helps in returning excess interstitial fluid to the bloodstream.
Step-by-step explanation:
Functions of Interstitial Fluid
Interstitial fluid (IF) is the fluid that exists in the spaces between cells and is a major component of the extracellular fluid. Its main function is to provide nutrients to cells and to remove waste products. The composition of interstitial fluid includes a variety of substances such as amino acids, sugars, fatty acids, salts, hormones, and neurotransmitters, which are important for cell function and intercellular communication. Materials such as these, as well as antibodies and white blood cells from the blood plasma, pass freely between the capillaries and the interstitial fluid through pores and intercellular clefts in the capillary endothelium.
Interstitial fluid and blood plasma communicate freely, but they have distinct compositions since certain elements like red blood cells and plasma proteins do not typically pass into the interstitial space. Additionally, 20 liters of plasma is filtered into the interstitial space daily, of which 17 liters is reabsorbed. The lymphatic system plays a critical role in draining excess interstitial fluid, now referred to as lymph, and returning it to the circulation, hence preventing lymphedema and other medical complications.