American Medical Technologist (AMT) Practice Exam

The major function of plasma proteins is to maintain oncotic pressure and transport substances. Plasma proteins, primarily albumin, play a crucial role in maintaining the osmotic balance between the blood and the tissues, which is vital for the proper distribution of fluids throughout the body. Oncotic pressure is the pulling force that helps keep fluid within the blood vessels, preventing excess fluid from leaking into surrounding tissues, which can lead to edema.

Additionally, plasma proteins have various transport functions. They bind to and carry substances such as hormones, vitamins, and waste products throughout the bloodstream, facilitating their transport to the appropriate sites within the body. This dual role of maintaining oncotic pressure and transportation is vital for overall homeostasis and physiological function, making it the primary function of plasma proteins.

While plasma proteins also play roles in blood clotting, immune response, and regulating blood pH, these functions are secondary compared to the fundamental importance of maintaining oncotic pressure and transporting essential substances.