The liver synthesizes many of the circulating plasma proteins, albumin being the most important (Fig. 28.5). It synthesizes about 3 g of albumin a day. Albumin plays an important role in preserving plasma volume and tissue fluid balance by maintaining the colloid osmotic pressure of plasma. This important function of plasma proteins is illustrated by the fact that both liver disease and long-term starvation result in generalized edema and ascites. Plasma albumin plays a pivotal role in the transport of many substances in blood, such as free fatty acids and certain drugs, including penicillin and salicylate.
The other major plasma proteins synthesized by the liver are components of the complement system, components of the blood clotting cascade (fibrinogen and prothrombin), and proteins involved in iron transport (transferrin, haptoglobin, and hemopexin) (see Chapter 11).
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.