How Carbohydrates Get Converted Into Energy
Carbohydrates are one of the primary sources of energy in the human diet. The process of converting carbohydrates into energy involves several steps:
1. Digestion
The journey starts in the mouth, where enzymes in saliva begin to break down starches into simpler sugars. This process continues in the stomach and small intestine, where carbohydrates are further digested into monosaccharides like glucose, fructose, and galactose.
2. Absorption
Once carbohydrates are broken down into monosaccharides, they are absorbed by the intestinal lining and enter the bloodstream. Glucose is the primary sugar transported to cells throughout the body.
3. Cellular Uptake
Insulin, a hormone released by the pancreas, facilitates the uptake of glucose into cells. Various tissues, including muscle and fat, utilize glucose to generate energy.
4. Glycolysis
Once inside the cells, glucose undergoes glycolysis, a series of enzymatic reactions that convert it into pyruvate. This process produces a small amount of ATP, the energy currency of the cell.
5. Citric Acid Cycle and Oxidative Phosphorylation
If oxygen is present, pyruvate enters the mitochondria and is converted into acetyl-CoA, entering the citric acid cycle (Krebs cycle). This cycle generates electron carriers, which fuel oxidative phosphorylation, producing a large yield of ATP.
Overall, the complete oxidation of one glucose molecule can yield up to 36-38 ATP molecules, providing cells with the energy required for various physiological functions.