Glucose, proteins, and lipids utilization for energy metabolism

Biology

How are glucose, proteins, and lipids utilized in your body to provide energy?

The human body is a fascinating self-regulating system that consists of interconnecting components. This structure of the body is central to the way it produces and uses energy (Singh, 2010). Proteins are made up of amino acid. Amino acids are the building-blocks of all cells. Protein is used by the body in order to build, maintain and replace tissue including muscle, hair, skin, organs and glands. It also works to produce hemoglobin, maintain proper immune function, and produce essential hormones and enzymes. Protein can also be broken down into glucose for energy. Without protein, a person's body would be unable to build muscle and carry out many of its essential life functions (the Skinny on Protein, Carbohydrates and Fats, 2008).

Foods that contain protein can be divided into two groups: complete proteins and incomplete proteins. Complete proteins include all nine essential amino acids that the body cannot produce by itself. With the exclusion of soy beans, complete proteins are only found in animal foods like meat, poultry, fish, eggs, and milk and dairy products. Incomplete proteins are missing in one or more of the nine essential amino acids. Incomplete resources of protein include most vegetables, as well as nuts, beans, seeds, peas and grains. Soybeans, however, are a complete protein (the Skinny on Protein, Carbohydrates and Fats, 2008).

Glucose is what the body uses for fuel. With no glucose, or without being able to change it into energy rapidly and efficiently, a person could not survive in good health. So it's very important that the body's energy-metabolism system works efficiently. Here is a very simple explanation of how a person converts glucose into energy.

In response to the rise in blood-glucose levels after meals, the pancreas releases insulin which mops up the glucose and carries it to cells that need extra energy.

The glucose goes into the cell by special molecules in the membrane called glucose transporters.

The cells that require glucose have specific insulin receptors on their surface so that insulin can bind to them, encouraging glucose entry and utilization in the cells.

Once in the cells, the glucose is burned in order to create heat and adenosine triphosyphate, (ATP) which is a molecule that stores and releases energy as required by the cell.

The metabolism of glucose into energy happens either in combination with oxygen which is called aerobic metabolism or without it which is called anaerobic metabolism. The oxygen used comes from the mitochondria. Red blood cells do not have mitochondria, so they convert glucose into energy without the use of oxygen, unlike some other cells.

Glucose is also converted to energy inside muscle cells. These are probably the most important energy users. Muscle cells contain mitochondria so they can process glucose with oxygen. Even if the level of oxygen levels in the muscle-cell mitochondria fall too low, the cells can proceed to convert glucose into energy without oxygen. The down side is that making glucose into energy without oxygen produces the by-product lactic acid. And too much lactic acid makes a person's muscles ache (How We Turn Glucose into Energy, 2006).