Final answer:
Osmolarity and ionic composition of blood plasma indicate the volume and pressure within blood vessels and the presence of specific proteins, but not the blood cell count, which requires a CBC test.
Step-by-step explanation:
Knowing the osmolarity and ionic composition of blood plasma provides a wealth of information about the physiological state of the body's fluids. However, it does not inform us about the blood cell count. Osmolarity and ionic composition reveal details about the electrolyte balance, which is crucial for maintaining proper osmotic pressure and blood pressure, as well as the volume of plasma through the regulation of water movement across cell membranes. The presence of specific proteins in plasma, such as albumin, contributes to the colloid osmotic pressure but does not specify the blood cell count.
The pressure within blood vessels can be influenced by the osmotic pressure in plasma. However, specific cell counts, such as the number of red blood cells or white blood cells, require a complete blood count (CBC) test and cannot be determined by osmolarity and ionic composition alone.