ThE DiGeStiVE SyStEM

The Digestive System contains organs for changing the food we eat chemically, for absorption by our body tissues. It is also responsible for processing food, and breaking it down into usable protein, minerals, carbohydrates and fats and other substances. The digestion process involves breaking food down into simple soluble substances absorbable by tissues.

The digestion process begins in your mouth when you start eating. The salivary glands produce secretions that are mixed with the food. The saliva breaks down starches into dextrin and maltose. Then it goes down your esophagus in peristaltic waves to the stomach. This only takes a matter of seconds. The stomach contains gastric juice and the gastric juice contains chemicals such as hydrochloric acid and some enzymes, including pepsin, rennin, and lipase.

Pepsin breaks proteins into peptones and proteases. Rennin separates milk into liquid and solid portions, and lipase acts on fat. Another function of stomach digestion is to gradually release materials into the upper small intestine, where digestion is completed.

After the solid food has been digested, the fluid remaining is called chyme. When it is thoroughly digested it passes through the pylorus sphincter to the small intestine. Here in the small intestine all the nutrients are absorbed from the chyme into the bloodstream leaving the rest as unusable residue. This residue passes through the colon or large intestine to the rectum. The solid waste, called feces, then passes through the canal and the anus.