Digestive System

body's complex series of glands and organs that aid in the breaking down of food.

Technically, the digestive system's process also known ad digestion, is the process of converting complex substances into simpler ones to allow the body to absorb and assimilate them easily. These complex substances are found in the food that we eat. From the time a person sees, smells, tastes or even thinks about food, it triggers the saliva in the mouth and the digestive juices [enzyme-carriers that break down food] to activate. This is called the cephalic [head] phase.

The actual digestion process starts when a person puts food in his mouth. The mouth contains tastebuds that determines the chemicals in the food via nerve endings; giving the taste sensations of sweet, sour, salty or bitter. A person's teeth initially grind and break down the bits of food. As a person chews food, it is mixed with saliva that is rich in enzymes and mucin to hasten the passage of food into the digestive tract. When the food is swallowed it passes through the esophagus and then into the stomach. The esophagus is a muscular tube that can contract and relax to propel food onwards. A mouthful of food takes around 6 seconds to reach the stomach after it has been swallowed.

When food reaches the stomach, the muscles work to churn and break down the food further. Digestive juices in the stomach is mixed to help kill possible bacteria and to halt the action of salivary amylase. The stomach also produces pepsin which helps break down proteins in food. The stomach also produces gherlin, which is a hormone that stimulates hunger and tends to increase prior to mealtime and decreases after eating. The churned food is converted into chyme which is a creamy mixture after the gastric phase. When the pyloric sphincter opens, chyme is passed gradually into the small intestine. This is known as the intestinal phase. Many hormones are secreted to help the digestive process. The digestion and absorption of proteins, carbohydrates and fats occur in the small intestine. Unabsorbed residue/s in this process passes through the small intestine and into the large intestine.

The large intestine contains more than 400 species of bacteria that help it break down and utilize the undigested residues. It is one of the most metabolically-active organs and it measures around 1.5 meters. The watery contents move along the large intestine and water is absorbed. The final product [feces] is formed and stored in the rectum prior to excretion.