The liver is described as the metabolic Workhorse of the body in that it facilitates metabolic processes for both macro and micronutrients. Provide a brief description of the significant roles that the liver plays with regard to nutrient metabolism

 

Answer:

Carbohydrate Metabolism

Maintainance of normal blood glucose levels over both short (hours) and long (days to weeks) periods of time is one particularly important function of the liver.

Two important examples of these abilities are:

• Excess glucose entering the blood after a meal is rapidly taken up by the liver and sequestered as the large polymer, glycogen (a process called glycogenesis). Later, when blood concentrations of glucose begin to decline, the liver activates other pathways which lead to depolymerization of glycogen (glycogenolysis) and export of glucose back into the blood for transport to all other tissues.
• When hepatic glycogen reserves become exhaused, livers recognize the problem and activate additional groups of enzymes that begin synthesizing glucose out of such things as amino acids and non-hexose carbohydrates (gluconeogenesis).

Fat Metabolism

Few aspects of lipid metabolism are unique to the liver, but many are carried out predominantly by the liver.

• The liver breaks down many more fatty acids that the hepatocytes need, and exports large quantities of acetoacetate into blood where it can be picked up and readily metabolized by other tissues.
• The liver is the major site for converting excess carbohydrates and proteins into fatty acids and triglyceride, which are then exported and stored in adipose tissue.

Protein Metabolism

The most critical aspects of protein metabolism that occur in the liver are:

• Deamination and transamination of amino acids, followed by conversion of the non-nitrogenous part of those molecules to glucose or lipids. Several of the enzymes used in these pathways (for example, alanine and aspartate aminotransferases) are commonly assayed in serum to assess liver damage.
• Removal of ammonia from the body by synthesis of urea.
• Synthesis of non-essential amino acids.
• Hepatocytes are responsible for synthesis of most of the plasma proteins. Albumin, the major plasma protein, is synthesized almost exclusively by the liver..