Final answer:
The composition of interstitial fluid is in equilibrium with blood plasma, both of which contribute to the extracellular fluid. The correct answer is A) Blood plasma, Extracellular fluid.
Step-by-step explanation:
The composition of the interstitial fluid is in equilibrium with the composition of blood plasma, so both contribute to the extracellular fluid. The correct answer is A) Blood plasma, Extracellular fluid.
Interstitial fluid, which bathes and surrounds the cells, is a key component of the extracellular fluid and includes plasma and lymph. It provides cells with nutrients and a means of waste removal. While interstitial fluid and blood plasma communicate freely, they are not identical, as large molecules like plasma proteins and cells such as red blood cells and platelets cannot pass through the capillary walls. The interstitial fluid mainly consists of water, amino acids, sugars, fatty acids, salts, and waste products whereas the blood plasma contains, in addition to these components, high concentrations of proteins and other elements critical for the body's functions.
Extracellular fluid (ECF) surrounds all cells in the body and is comprised of two primary constituents: the fluid component of the blood (plasma) and the interstitial fluid (IF) that surrounds all cells not in the blood.