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How much of blood plasma is water?
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blood
Blood sediment in test tubes, showing plasma (clear fluid), red blood cells (red), and the release of hemoglobin into the surrounding plasma (pink).
Plasma, the liquid portion of blood, is composed of 90 to 92 percent water.21
This water is essential for maintaining the hydration of body tissues and is freely exchangeable with other extracellular fluids. While water makes up the vast majority of plasma, the remaining portion consists of critical solutes, including proteins (such as serum albumin), electrolytes, hormones, and various nutrients and waste products necessary for sustaining life.21