Digestion is the chemical process of creating energy from food. It starts at the mouth and ends at the anus where the waste is excreted. This process is facilitated by special chemicals called digestive enzymes, which are secreted by the stomach, liver and pancreas. They break the food down into small enough pieces to be absorbed. These nutrients are then distributed to body parts that need them for growth, repair, and energy. Good health is vitally dependent on good digestion.
This is where digestion starts. The teeth and saliva are the first step to breaking the food down.
This is the tube that leads from your mouth to the stomach.
The stomach secretes hydrochloric acid, which breaks the food down into a liquid so that the nutrients can be separated from the waste. Low stomach acid can result in absorption problems, constipation, bloating, gas and also the growth of Helicobactor pylori, a bacterium found to cause stomach ulcers.
The small intestine
The small intestine is a long, tubular organ, which has muscular walls that create a wave-like motion called peristalsis. This is done to move the contents along. The small intestine is just the right length to allow the processes of digestion and absorption to take place completely.
The inner surface of the small intestine is not smooth but has folds with finger-like projections called villi. This folding and the presence of villi increase the surface area available for absorption.
Most digestion and absorption takes place in the small intestine.
Liver and Gall bladder
The liver’s digestive function is to produce a fluid called bile. This bile is a natural laxative and is stored in the gallbladder, a sac on the inferior surface of the liver. It then flows through various ducts and eventually enters the duodenum (the first part of the small intestine).
The Large Intestine (Colon)
The primary function of the large intestines is the salvaging of water and electrolytes (salts) and also to secrete mucus for lubrication. Most of the end products of digestion have already been absorbed in the small intestine. Within the large intestine, the contents are first a watery fluid. The large intestine removes water until a nearly solid mass is formed before defecation, the evacuation of feces.
The large intestine joins the small intestine at the ascending colon (going up), then becomes the transverse colon, and the descending colon (going down), and finally the sigmoid colon. The fecal mass is stored in the sigmoid colon until passed into the rectum.
The final storage of feces is in the rectum. The rectum terminates in the narrow anal canal, which is about one and a half inches long in the adult. At the end of the anal canal is the opening called the anus. Muscles called the anal sphincters aid in the retention of feces until defecation.