Plasma is approximately made up of 90% water and what percentage of dissolved substances?

Plasma is a crucial component of blood, constituting about 55% of its total volume, and it serves as a medium for carrying various substances throughout the body. In understanding the composition of plasma, it is essential to know that approximately 90% of plasma is indeed water, which is fundamental for maintaining fluid balance and transporting nutrients. The remaining portion is made up of dissolved substances, including proteins, electrolytes, hormones, nutrients, and waste products.

If plasma is 90% water, then the dissolved substances comprise the remaining 10%. Therefore, when considering the total volume of plasma, the correct understanding is that around 10% consists of these various dissolved constituents. This percentage is critical because it highlights the importance of these substances in processes such as nutrient transport, immune response, and waste removal from the bloodstream.

The correct answer reflects the balance in plasma's composition and helps in understanding the physiological roles of blood components in health and disease.