The main and largest component of blood plasma is:

Blood plasma is the liquid component of blood, making up about 55% of total blood volume. It is a straw-colored fluid that serves as the medium for transporting nutrients, hormones, proteins, and waste products throughout the body. Among its various components, the largest and main component of blood plasma is water, which accounts for approximately 90–92% of plasma by volume.

Water in plasma is essential for maintaining blood volume and pressure, facilitating transport of soluble substances, and regulating body temperature. It provides a medium for dissolved electrolytes like sodium, potassium, and chloride, which are critical for nerve and muscle function. Water also helps in carrying nutrients, such as glucose, amino acids, and fatty acids, to body tissues, and transporting waste products, such as carbon dioxide and urea, to the lungs and kidneys for removal.

Other minor components of plasma include proteins (albumin, globulins, fibrinogen), gases (oxygen and carbon dioxide), hormones, and nutrients like glucose. While oxygen and carbon dioxide are dissolved in plasma, they exist in much smaller amounts compared to water. Glucose is also present but forms only a tiny fraction of the plasma composition.

Understanding that water is the main component of plasma is a fundamental concept in biology, especially in human physiology and hematology. It highlights the critical role of plasma in transporting essential substances, maintaining homeostasis, and supporting the body’s overall metabolic functions. Without sufficient water in plasma, blood would become more viscous, and the transport of nutrients and waste would be impaired, affecting every organ and system in the body.