Diagram of the digestive system

The human digestive system is a complex series of organs that works in such a way that helps people's systems break down food and absorb it. The complete digestive tract is composed of hollow organs, joined in a long and twisting tube that extends from the mouth to the anus. Organs that make the digestive tract are: anus, appendix, esophagus, gallbladder, large intestine, liver, pancreas, rectum, small intestine and stomach. All organisms use different organs and different processing mechanisms to digest food. How does the digestive system work?

In humans, food enters the mouth where it is being chewed by teeth. This is where the mechanical and chemical breakdown of the food starts. The saliva, a component of oral fluids, contains various sorts of enzymes that help the breakdown of the starch and fat in the food at the molecular level. From here, semi-processed food travels down the esophagus and reaches the stomach. The stomach is a muscular, hollow, dilated part of the alimentary canal, which secretes the protein-digesting enzymes and strong acids to aid in the food digestion. Hydrochloric acid in the stomach is strong enough to kill or inhibit most harmful microorganisms contained in some food items. Food is churned by the stomach through muscular contractions of the wall, until it is converted into a partially digested bulk, known as chyme. This process typically lasts an hour or two in humans. The chyme travels further through the pyloric sphincter and into the small intestine where 95% of absorption of nutrients occurs. The food is then passed through the large intestine and finally excreted during the defecation.

Digestive system factsThe esophagus of adult human beings has 10 to 14 inches in length, and 1 inch in diameter. A stomach of an adult human can hold somewhere around 1.5 liters of food and liquid. An average male person, weighting somewhere around 150 pounds, will eat approximately 50 tons of food during the lifetime. Human colon is a habitat for more than 400 various species of bacteria. The liver is the largest organ in the human body. The liver is responsible for more than 500 different roles in the human body. The complete process of digestion in healthy adults usually takes between 24 and 72 hours. Adults make around 2 pints of saliva each day. Stomach is shaped like the letter J. To keep the stomach from digesting itself, it produces a mucous layer every two weeks. Humans eat about 500 kilograms of food for each year.