Fructose is absorbed by facilitated diffusion while glucose and galactose are actively transported. The first organ to receive glucose, fructose, and galactose is the liver. The liver takes them up and converts galactose to glucose, breaks fructose into even smaller carbon-containing units, and either stores glucose as glycogen or exports it back to the blood. How much glucose the liver exports to the blood is under hormonal control and you will soon discover that even the glucose itself regulates its concentrations in the blood.
The short-chain fatty acids are either used by the bacteria to make energy and grow, are eliminated in the feces, or are absorbed into cells of the colon, with a small amount being transported to the liver. Colonic cells use the short-chain fatty acids to support some of their functions.
The amino acids are absorbed into the bloodstream through the small intestines. The steps in protein digestion are summarized in Figure 2 and Table 2. The digestion of carbohydrates begins in the mouth. The salivary enzyme amylase begins the breakdown of food starches into maltose, a disaccharide.
Gastrointestinal Tract, The tube that extends from the mouth to the anus in which the movement of muscles and release of hormones and enzymes digest food. Cholecystokinin (also called pancreozymin), this is a hormone in the small intestinal cells (intestinal mucosa) that is produced in response to food. A bitter, alkaline, brownish-yellow or greenish-yellow fluid that is secreted by the liver, stored in the gallbladder, and discharged into the duodenum and aids in the emulsification, digestion, and absorption of fats.
This hormone is secreted in response to fat in chyme. There are at least five hormones that aid and regulate the digestive system in mammals. There are variations across the vertebrates, as for instance in birds. Arrangements are complex and additional details are regularly discovered.
The glucose thermostat is located within the cells of the pancreas. After eating a meal containing carbohydrates glucose levels rise in the blood. The organs produce digestive chemicals (enzymes and acids) that break down the nutrients into simpler forms so that absorption through the intestinal wall and into the blood stream can occur. Digestion is a complex process controlled by several factors. pH plays a crucial role in a normally functioning digestive tract.
Throughout the digestive tract, smooth muscle peristalsis aids in transporting food. Watch a stop-motion video of digestion from the mouth down to the small intestine from a TEDxManhattan fellow via Scientific American. The regions of the large intestine are the appendix, cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anal canal. The large intestine absorbs water, electrolytes, and vitamins that remain after chyme is passed from the small intestine.
Such blockages can be dangerous if they block the passage of food into the small intestine. In some cases, a single organ is in charge of a digestive process.