Composition of Blood Plasma

Blood plasma is a fluid that contains approximately 92% water and 8% solutes. The solutes include various types of proteins, which constitute about 7% of the total solutes in the plasma. The high-molecular-weight proteins—albumins, globulins, and fibrinogen—are essential to plasma function. Albumins, making up about 60% of the plasma proteins, maintain the osmotic balance within blood vessels by preventing excessive water leakage. Additionally, albumins serve as carrier proteins, binding to substances such as fatty acids and hormones.

Globulins are the second most abundant type of plasma protein, divided into alpha, beta, and gamma globulins. The alpha and beta globulins transport lipids, metal ions, and fat-soluble vitamins. Gamma globulins, or immunoglobulins, are released by plasma cells and play a crucial role in immune responses.

Fibrinogen, another high-molecular-weight protein, is vital for blood clotting. Following an injury, fibrinogen transforms into insoluble fibrin, creating a mesh that traps blood cells, platelets, and proteins, facilitating the formation of a blood clot.

Lastly, a small fraction of the plasma proteins consists of regulatory molecules, including enzymes and hormones. Besides proteins, the remaining 1% of the plasma comprises various other solutes, such as electrolytes, respiratory gases, organic nutrients like carbohydrates, and waste products like urea and creatinine.