Final answer:
The two sets of receptors that measure the body's fluid balance are for the extracellular fluid and the cells. The extracellular fluid includes components such as blood plasma and interstitial fluid, while cells contain intracellular fluid, both critical for physiological processes and maintaining homeostasis.
Step-by-step explanation:
To maintain proper fluid balance, the body contains two sets of receptors: one measures the volume of the extracellular fluid, and the other records the volume of the cells. The correct answer to this question is option 2) extracellular fluid; cells.
Extracellular fluid (ECF) is a crucial component of the body's fluid system. It includes blood plasma, interstitial fluid, and lymph. This fluid has an essential role in maintaining not only the overall osmotic pressure across membranes but also specific concentrations of important electrolytes. Moreover, the ECF is where the interstitial fluid surrounds the cells that are not blood cells, providing a medium for the exchange of substances between the blood and cell interior.
On the other hand, cells themselves contain intracellular fluid (ICF), which represents the system that includes all fluid enclosed in cells by their plasma membranes. The constant exchange of substances between the ECF and ICF is vital for homeostasis, including fluid volume regulation.