villi structures absorb most of the products of digestion in the small intestine.
villi structures absorb most of the products of digestion in the small intestine.
what structures absorb most of the products of digestion in the small intestine?
villi
after this, the digesta is moved to the true stomach, the abomasum. this is the gastric compartment of the ruminant stomach. the abomasum is the direct equivalent of the monogastric stomach, and digesta is digested here in much the same way. this compartment releases acids and enzymes that further digest the material passing through. this is also where the ruminant digests the microbes produced in the rumen. digesta is finally moved into the small intestine, where the digestion and absorption of nutrients occurs. the small intestine is the main site of nutrient absorption. the surface area of the digesta is greatly increased here because of the villi that are in the small intestine. this increased surface area allows for greater nutrient absorption. microbes produced in the reticulorumen are also digested in the small intestine. after the small intestine is the large intestine. the major roles here are breaking down mainly fiber by fermentation with microbes, absorption of water (ions and minerals) and other fermented products, and also expelling waste. fermentation continues in the large intestine in the same way as in the reticulorumen.
ruminant
as with other vertebrates, the intestines of fish consist of two segments, the small intestine and the large intestine. in most higher vertebrates, the small intestine is further divided into the duodenum and other parts. in fish, the divisions of the small intestine are not as clear, and the terms "anterior intestine" or "proximal intestine" may be used instead of duodenum. in bony fish, the intestine is relatively short, typically around one and a half times the length of the fish's body. it commonly has a number of "pyloric caeca", small pouch-like structures along its length that help to increase the overall surface area of the organ for digesting food. there is no ileocaecal valve in teleosts, with the boundary between the small intestine and the rectum being marked only by the end of the digestive epithelium. there is no small intestine as such in non-teleost fish, such as sharks, sturgeons, and lungfish. instead, the digestive part of the gut forms a "spiral intestine", connecting the stomach to the rectum. in this type of gut, the intestine itself is relatively straight, but has a long fold running along the inner surface in a spiral fashion, sometimes for dozens of turns. this fold creates a valve-like structure that greatly increases both the surface area and the effective length of the intestine. the lining of the spiral intestine is similar to that of the small intestine in teleosts and non-mammalian tetrapods. in lampreys, the spiral valve is extremely small, possibly because their diet requires little digestion. hagfish have no spiral valve at all, with digestion occurring for almost the entire length of the intestine, which is not subdivided into different regions.
fish anatomy