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Carbohydrate Metabolism

Learn how your body breaks down carbohydrates and the important role they play in your metabolism and overall health.

Review of Carbohydrate Metabolism

Carbohydrates are a major source of energy in the body, providing the necessary fuel for cells and organs to function properly. Understanding the complex process of carbohydrate metabolism is important for maintaining optimal health and well-being. In this article, we will review the physiology of carbohydrate metabolism and its role in the body.


Carbohydrates are made up of carbon, hydrogen, and oxygen atoms and are the most abundant organic molecules in the body. They are divided into three main categories: monosaccharides, disaccharides, and polysaccharides. Monosaccharides are simple sugars such as glucose, fructose, and galactose; disaccharides are two monosaccharides linked together such as sucrose (glucose plus fructose) and maltose (glucose plus glucose); and polysaccharides are multiple monosaccharides linked together, such as starch and cellulose.

Carbohydrates are broken down and digested in the small intestine, where monosaccharides are absorbed into the bloodstream and transported to the liver. The liver then processes the carbohydrates and either stores them as glycogen or sends them to other cells in the body for energy. This process is known as carbohydrate metabolism.

Pathways of Carbohydrate Metabolism

Carbohydrate metabolism consists of several pathways that occur in the body. The two main pathways of carbohydrate metabolism are glycolysis and the Krebs cycle.


Glycolysis is the first step in carbohydrate metabolism and is the process of breaking down glucose molecules into two molecules of pyruvate. This process takes place in the cytoplasm of cells and does not require oxygen. During glycolysis, two molecules of ATP (adenosine triphosphate) are produced. ATP is the form of energy used by cells for various processes.

The Krebs Cycle

The Krebs cycle is the next step in carbohydrate metabolism and is also known as the citric acid cycle. This process takes place in the mitochondria of cells and requires oxygen to complete. During the Krebs cycle, pyruvate molecules are converted into Acetyl-CoA molecules and then broken down into carbon dioxide and water. This process also produces ATP molecules and other molecules that can be used in other metabolic pathways.

Regulation of Carbohydrate Metabolism

Carbohydrate metabolism is regulated by hormones, enzymes, and other molecules in the body. Hormones such as insulin and glucagon play a major role in regulating carbohydrate metabolism by controlling the uptake and release of glucose into the bloodstream. Insulin stimulates the uptake of glucose into cells and glucagon stimulates the release of glucose from the liver.

Enzymes are also important for regulating carbohydrate metabolism. Enzymes are proteins that catalyze biochemical reactions in the body. They are specific to particular metabolic pathways and help speed up or slow down the rate of reaction.

Other molecules such as vitamins and minerals are also involved in regulating carbohydrate metabolism. Vitamins such as thiamin (B1), riboflavin (B2), and niacin (B3) are essential for the metabolism of carbohydrates. Minerals such as magnesium, zinc, and iron are also important for carbohydrate metabolism.


Carbohydrate metabolism is a complex process that is essential for the proper functioning of the body. Understanding the pathways and regulation of carbohydrate metabolism is important for maintaining optimal health and well-being.

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