The Digestive Process starts with Chewing.
Chewing the food thoroughly is the first step toward getting the most from the food you eat. Chewing signals other components of the digestive process to get ready to go to work; it also allows food to mix with saliva. Saliva contains the enzyme salivary amylase to break down starch molecules into smaller sugars. Once the food has been chewed, it is transported through the esophagus into the stomach.
Food is broken down in the stomach by mechanical as well as chemical means. The stomach churns and gyrates to promote the mixing of the food with its digestive secretion, including hydrochloric acids and the enzyme pepsin. These factors are critical to proper protein digestion and mineral absorption.
Secretions of Hydrochloric Acid is important in the Digestive process.
If hydrochloric acid secretion is insufficient or inhibited proper protein digestion will not occur. Food remains in the stomach until it is reduced to semi liquid consistency. In general this process takes 45 minutes to four hours. Once the food material leaves the stomach it is referred to as Chyme. It takes Chyme approximately two to four hours to make it way through 21-foot long small intestine. The small intestine is divided into three segments; the duodenum is the first 10 to 12 inches the jejunum is the middle portion and is about 8 feet long.
Digestion, Absorption and Transporting of ingested Food.
The small intestine participates in all aspects of digestion, absorption, and transport of the ingested material.
It secrets a variety of digestive and protective substance as well as receives the secretion of the pancreas, liver and gallbladder.
Absorption of minerals occurs predominately in the duodenum absorption of the water soluble vitamins,carbohydrates, and protein occurs primarily in the jejunum; and the ileum absorbs fat-soluble vitamins, fats, cholesterol, and bile salts.
Diseases involving the small intestine often result in malabsorption syndromes characterized by multiple nutrient deficiencies. Examples of common cause of malabsorption include celiac disease ( gluten intolerance ), food allergy or intolerance, intestinal infection and Crohns disease. The pancreas produces enzymes that are required for the digestion and absorption of food.
Each day the pancreas secretes about 1.5 quarts of pancreatic juices in the small intestine. Enzymes secreted include lipases, proteases and amylases. Lipases, along with bile, function in the digestion of fats. Deficiency of lipases results in malabsorption of fats and fat soluble vitamins. Amylases break down starch molecules into smaller sugars. The salivary glands as well as the pancreas secrete amylase.
The proteases secreted by the pancreas (trypsin, chymotrypsin, and carboxpeptidase) function in digestion by breaking down protein molecules into single amino acids. Incomplete digestion of proteins creates a number of problems for the body, including the development of allergies and formaton of toxic substances during putrefaction (the break down of protein by bacteria).