Quiz 12: Drugs for the Gastrointestinal System
Food that is ingested is in complex organic form and cannot be utilized as it is by the body. It needs to be broken into simpler forms. The food that we ingest passes through the gastrointestinal tract before being excreted through the anus. The gastrointestinal tract performs the following important functions. 1. Movement or propulsion of food Since the food cannot be absorbed by the body in the state that it is ingested, it needs to be processed further. For processing, it must pass through the entire gastrointestinal tract. The gastrointestinal tract has smooth muscles that alternately contract and relax by a mechanism referred to as peristalsis. 2. Secretion The gastrointestinal tract has got various enzymes that specialize in breaking down specific organic substances into their simpler forms. These cause chemical breakdown of food. 3. Digestion Digestion of food is mechanical as well as chemical. Mechanically food is first broken down in the mouth by chewing and then further in the gastric region by segmentation. Segmentation involves the churning of food back and forth by rhythmic contraction and relaxation of muscles in the gastric region. 4. Absorption Once the food is digested it gets is available as nutrients to the body. Nutrients are absorbed from the tract by blood vessels and lymphatic vessels in the region. 5. Excretion Waste material resulting after the entire process is completed, are eliminated through the large intestinal region of the tract.
Food that is ingested is in complex organic form and cannot be utilized as it is by the body. It needs to be broken into simpler forms. The food that we ingest from the mouth passes through esophagus, stomach, small intestine, liver, gall bladder, pancreas and the large intestine. The various parts of the gastrointestinal system and their activities are as follows. 1. Mouth Food is ingested through the mouth. It is broken down into smaller pieces mechanically by chewing. The teeth and tongue help in the process. The saliva helps in making the food moist, which helps in the propulsion of food further down the tract. Enzyme amylase in saliva helps in preliminary breakdown of carbohydrates and starch in the food. 2. Esophagus The esophagus allows passage of food from the mouth to the stomach. It has an esophageal sphincter at its inferior end that closes when food is passed into the stomach. It prevents the regurgitation of food in the esophagus. 3. Stomach The stomach has gastric lining that has many folds and secretes gastric juices. Stomach is the site where mechanical and chemical digestion of food takes place. The mechanical digestion is by way of segmentation. Segmentation involves the churning of food back and forth by rhythmic contraction and relaxation of muscles in the gastric region. The chemical digestion is brought about by the gastric juices. The juices help in maintaining the pH of the region, that kills bacteria in the food and converts the food in a liquid mass called chyme. 4. Small intestine the small intestine is the site where all the digested food gets mixed with the various secretions form the liver and pancreas and gets converted to available nutrients that are then absorbed by the blood and lymphatic vessels in the regions. The intestine is coiled and has several folds that increase its surface area and help in maximizing the absorption of nutrients. 5. Liver Liver secretes bile that enters the intestine and helps in absorption. It also stores nutrients from the intestine. The liver plays the important role of purifying blood coming from the gastrointestinal tract before it is distributed to the entire body. It also deactivates and metabolizes drugs. 6. Gall bladder When the bile is not used by the intestine, it gets stored in the gall bladder. 7. Pancreas The process of absorption is completed when pancreatic juices finally convert the complex organic food particles into carbohydrates, sugar and fat. The pancreas also regulate blood sugar by secretion of insulin. 8. Large intestine Waste material resulting after the entire process is completed, are eliminated through the large intestine as feces.