The Human digestive system

• The major nutrients required for a healthy diet are carbohydrates, proteins and lipids.
• The digestive system breaks down large molecules of food, which are then absorbed into the bloodstream.
• The human digestive system has two functions: it breaks down complex food substances and it provides the very large surface area for maximum absorption of food.
• The structure of the digestive system consists of regions: the mouth, the stomach, the small intestine, the large intestine, and the liver.
• The regions of the digestive system are adapted to the digestion and absorption of food.
• The mouth begins the digestion of carbohydrates.
• The stomach begins the digestion of protein; small molecules such as alcohol are absorbed.
• The small intestine continues the digestion of carbohydrate and protein; it begins the digestion of lipids.
• The small intestine, specifically the ileum, completes the digestion of carbohydrates and proteins into single sugars and amino acids; it is also involved in the absorption of single sugars, amino acids and fatty acids and glycerol.
• Villi is the plural of villus.
• Villi are finger-like projections in the small intestine that provide a large surface area for the absorption of food.
• The epithelial cells that cover each villus themselves have projections called microvilli.
• Most of the digested food passes through the epithelial cells of the gut wall and is carried by blood to the liver.
• Function of the pancreas is to complete the digestion of carbohydrates and proteins into single sugars and amino acids, and the absorption of single sugars, amino acids and fatty acids and glycerol.
• The large intestine is involved in the absorption of water and the egestion of undigested food.
• Digested lipids pass through the gut wall and enter the lacteals.
• Villi and microvilli increase the surface area over which digested food – now simple molecules – is absorbed.
• Microvilli are projections from the surface of an epithelial cell of the small intestine wall.
• Digestive enzymes are used to break down food in the gut.
• The digestive system is involved in breaking down complex food molecules and the absorption of simple food molecules into the bloodstream.
• The large intestine is involved in the absorption of water and the egestion of undigested food.