digestive system?Describe how the digestive system functions so glucose in food from the outside environment ends up in the cells mitochondria.
Posted by Emerson
Macromolecules such as carbohydrates are broken down and absorbed by the small intestine. Once absorbed, molecules of glucose are then absorbed into the bloodstream where it enters aerobic respiration. Glucose is broken down into pryruvic acid through a process of Glycolysis. It is the pyruvate that is allowed to enter the mitochondria to become citric acid in the krebs cycle.
Posted by efulufu
If you are talking solely about glucose it saves a lot of explaining because glucose is already a form of carbohydrate that is readily absorbable into the blood. Glucose goes through your mouth, oesophagus, stomach relatively untouched. At the small intestine, it is absorbed by the microvilli on the intestine wall. The glucose enters the blood and goes into various cells of the body that need it. However, note that the concentration of glucose in the blood is closely regulated by insulin and glucagon as part of homeostasis so that the concentration is maintained at 70 to 150 mg/dL. At the various cells that need it (eg. muscle, nerves etc.), glucose undergoes cellular respiration which involves glycolysis in the cytosol whereby glucose is turned into two molecules of pyruvate. Pyruvate is converted to acetyl CoA with the addition of a molecule of CoA and the removal of CO2. It is acetyl CoA which enters the mitochondria, not glucose. Only the acetyl part is needed for the Krebs cycle inside the mitochondria.
Much of these processes does not involve the digestive system so i think you have to check what you actually want to ask. It could be that you are more interested in the digestion of carbohydrate to glucose which involves the digestive system, yes. Cheers though.
How the Body Works : The Digestive System
The Digestive System Starting at the mouth, the digestive system helps provide the energy your body needs to perform its many functions. Upon entry into a person's mouth, the teeth cut, tear, crush and grind food. In the mouth, salivary glands respond to the thought or presence of food by producing a fluid containing mucus and the enzymes amylase and maltase. The tongue then mixes the food and rolls it into a soft ball, called the bolus, which is pushed toward the esophagus. Passing through the esophagus the bolus is dropped into the stomach where gastric glands, one secreting digestive enzymes and the other secreting hydrochloric acid, begin to break the food down into smaller pieces. The stomach wall discharges mucus during this phase to protect itself against the action of the gastric acid. From there the food passes into the small intestine through the phylorus, a sphincter muscle that controls the flow of food. It is in the small intestine where a major part of digestion and absorption occurs. The intestinal wall releases enzymes which digest proteins, fats and carbohydrates. Blood and lymph vessels, which supply the small intestine, take away the final products of digestion. The lymphatics transport the fats around the body and finally release them into the bloodstream. Blood takes sugars and amino acids to the liver via the portal vein. The pancreas, like the small intestine, secretes enzymes in an alkaline juice to digest proteins, fats and carbohydrates. It also ...
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