Where are plasma proteins synthesized?

Plasma proteins are primarily synthesized in the liver. The liver plays a crucial role in the production of many important proteins that circulate in the blood, including albumin, fibrinogen, and various globulins. Albumin accounts for a significant portion of plasma proteins and is essential for maintaining osmotic pressure and transporting various substances in the blood.

The liver's ability to synthesize these proteins is vital for several physiological functions, including clotting, immune responses, and maintaining blood volume and pressure. This function underscores the central role of the liver in maintaining homeostasis and proper bodily functions.

In contrast, while the kidneys, pancreas, and lungs contribute to various biochemical processes in the body, they are not the primary sites for the synthesis of plasma proteins. The kidneys are more involved in regulating electrolytes and filtering waste, the pancreas produces digestive enzymes and hormones like insulin, and the lungs are primarily responsible for gas exchange, not protein synthesis. Thus, the liver is the correct answer for the synthesis of plasma proteins.