Instruct: Given a question, retrieve relevant documents that answer the question.
Query: What are the parts of the small intestine?
The small intestine or small bowel is the part of the gastrointestinal tract between the stomach and the large intestine, and is where most of the end absorption of food takes place. The small intestine has three distinct regions – the duodenum, jejunum, and ileum. The duodenum is the shortest part of the small intestine and is where preparation for absorption begins. It also receives bile and pancreatic juice through the pancreatic duct, controlled by the sphincter of Oddi. The primary function of the small intestine is the absorption of nutrients and minerals from food, using small finger-like protrusions called villi.[2]
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 valve 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.
The life cycle begins with eggs being ingested. The eggs hatch in the duodenum (i.e., first part of the small intestine). The emerging pinworm larvae grow rapidly to a size of 140 to 150 μm, and migrate through the small intestine towards the colon. During this migration, they moult twice and become adults. Females survive for 5 to 13 weeks, and males about 7 weeks. The male and female pinworms mate in the ileum (i.e., last part of the small intestine), whereafter the male pinworms usually die, and are passed out with stool. The gravid female pinworms settle in the ileum, caecum (i.e., beginning of the large intestine), appendix and ascending colon, where they attach themselves to the mucosa and ingest colonic contents.
Many legume seeds have been proven to contain high lectin activity, termed "hemagglutination." Soybean is the most important grain legume crop in this category. Its seeds contain high activity of soybean lectins (soybean agglutinin or SBA). SBA is able to disrupt small intestinal metabolism and damage small intestinal villi via the ability of lectins to bind with brush border surfaces in the distal part of small intestine.
Lepidotrichia are bony, bilaterally-paired, segmented fin rays found in bony fishes. They develop around actinotrichia as part of the dermal exoskeleton. Lepidotrichia may have some cartilage or bone in them as well. They are actually segmented and appear as a series of disks stacked one on top of another. The genetic basis for the formation of the fin rays is thought to be genes coding for the proteins actinodin 1 and actinodin 2.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.
Food then moves on to the jejunum. This is the most nutrient absorptive section of the small intestine. The liver regulates the level of nutrients absorbed into the blood system from the small intestine. From the jejunum, whatever food that has not been absorbed is sent to the ileum which connects to the large intestine. The first part of the large intestine is the cecum and the second portion is the colon. The large intestine reabsorbs water and forms fecal matter.
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 valve 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.[21]
Duodenitis, jejunitis and ileitis are subtypes of enteritis which are only localised to a specific part of the small intestine. Inflammation of both the stomach and small intestine is referred to as gastroenteritis. 
With this type of surgery, a reservoir, or pouch, is created out of approximately two feet of the ascending colon and a portion of the ileum (a part of the small intestine). The ureters are surgically removed from the bladder and repositioned to drain into this new pouch. The end of the segment of small intestine is brought out through a small opening in the abdominal wall called a stoma. Since a segment including the large and small intestines is utilized, also included in this new system is the ileocecal valve. This is a one-way valve located between the small and large intestines. This valve normally prevents the passage of bacteria and digested matter from re-entering the small intestine. Originally, it was thought that removing the ileocecal valve from the digestive tract would likely result in diarrhea, but this has not shown to be the case. After a period of several weeks, the body adjusts to the absence of this valve (from the digestive tract) by absorbing more liquids and nutrients. Importantly, this valve, in its new capacity, will now effectively prevent the escape of urine from the stoma. The passage of the conduit through the abdominal wall allows the rectus abdominis muscle to aid with continence.
The horse’s small intestine is long and holds . This is the major digestive organ, and where most nutrients are absorbed. It has three parts, the duodenum, jejunum and ileum. The majority of digestion occurs in the duodenum while the majority of absorption occurs in the jejunum. Bile from the liver aids in digesting fats in the duodenum combined with enzymes from the pancreas and small intestine. Horses do not have a gall bladder, so bile flows constantly. Most food is digested and absorbed into the bloodstream from the small intestine, including proteins, simple carbohydrate, fats, and vitamins A, D, . Any remaining liquids and roughage move into the large intestine.
The lower gastrointestinal tract includes most of the small intestine and all of the large intestine. In human anatomy, the intestine (bowel, or gut. Greek: éntera) is the segment of the gastrointestinal tract extending from the pyloric sphincter of the stomach to the anus and, as in other mammals, consists of two segments, the small intestine and the large intestine. In humans, the small intestine is further subdivided into the duodenum, jejunum and ileum while the large intestine is subdivided into the, cecum, ascending, transverse, descending and sigmoid colon, rectum, and anal canal.
The small intestine supports the body's immune system.[16] The presence of gut flora appears to contribute positively to the host's immune system. Peyer's patches, located within the ileum of the small intestine, are an important part of the digestive tract's local immune system. They are part of the lymphatic system, and provide a site for antigens from potentially harmful bacteria or other microorganisms in the digestive tract to be sampled, and subsequently presented to the immune system.[17]
Small intestine cancer can be subdivided into duodenal cancer (the first part of the small intestine) and cancer of the jejunum and ileum (the later two parts of the small intestine). Duodenal cancer has more in common with stomach cancer, while cancer of the jejunum and ileum have more in common with colorectal cancer. Five year survival rates are 65%.
From the stomach, food passes to the small intestine, where a battery of digestive enzymes continue the digestive process. The products of digestion are absorbed across the wall of the intestine into the bloodstream. What remains is emptied into the large intestine, where some of the remaining water and minerals are absorbed; here the digestion is intracellular.
In addition to sleeve gastrectomy procedure, the connection between the stomach and the duodenum is closed off from the level of the second segment of the duodenum. While preserving the last 30 cm part of the small intestine, a 170 cm segment of ileum is prepared and connected to the first segment of the duodenum, which is at the end of the stomach. The other end of the ileum segment is connected to the proximal part of the small intestine. Thus, distal part of the small intestine is ‘’interposed’’ between proximal part of the small intestine and the stomach. Since duodenum and the proximal part of the small intestine is disabled, a partial bypass is in question. Patients who undergo this operation achieve better weight and blood sugar control, but face anemia (iron deficiency) risk because of the bypass procedure.
Aside from pork rind, chicken skin may also be made into , whereas —literally 'flower chicharrón', named for its distinctive shape—is made from pig mesentery. In anatomy, "mesentery" refers to the fold of the peritoneum (membrane lining the cavity of the abdomen) attaching the stomach, small intestine and other organs to the posterior wall of the abdomen. However, in this context it usually refers to the small bowel mesentery, a fold of tissue that anchors the small intestine to the back of the abdominal wall. It is the thin, web-like structure that supports the small intestine while allowing for the changes in their size and position. When the intestine is detached from this mesentery, the outside thin part of the latter forms a frill or ruffled-like ornament resembling a flower, hence the name of the meat and dish. 
In the pancreas the role of dopamine is somewhat complex. The pancreas consists of two parts, an exocrine and an endocrine component. The exocrine part synthesizes and secretes digestive enzymes and other substances, including dopamine, into the small intestine.[66] The function of this secreted dopamine after it enters the small intestine is not clearly established—the possibilities include protecting the intestinal mucosa from damage and reducing gastrointestinal motility (the rate at which content moves through the digestive system).[66]
Intestinal bacteria convert the conjugated bilirubin that is excreted by the bile duct into the intestine into urobilinogen and stercobilinogen. Part of the urobilinogen is reabsorbed in the intestine then circulated in the blood to the liver where it is excreted. A small part of this recirculated urobilinogen is filtered out by the kidneys and appears in urine (less than 1 mg/dl urine). The stercobilinogen can not be reabsorbed and remains in the intestine.
The small intestine is divided into three structural parts.
As a result of its slow digestion, isomaltulose reaches more distally in the human small intestine than does sucrose, as evidenced by their different incretin hormones responses. The incretin hormone glucose-dependent insulinotropic polypeptide (GIP) is secreted from the earlier (proximal) part of the small intestine in lower amounts after isomaltulose than for sucrose ingestion, whereas the incretin hormone glucagon-like peptide-1 (GLP-1) is secreted from a later (distal) part of the small intestine in higher amounts with isomaltulose compared with sucrose.
The three sections of the small intestine look similar to each other at a microscopic level, but there are some important differences. The parts of the intestine are as follows:
The lower gastrointestinal tract (GI), includes the small intestine and all of the large intestine. The intestine is also called the bowel or the gut. The lower GI starts at the pyloric sphincter of the stomach and finishes at the anus. The small intestine is subdivided into the duodenum, the jejunum and the ileum. The cecum marks the division between the small and large intestine. The large intestine includes the rectum and anal canal.
The small intestine is where most chemical digestion takes place. Many of the digestive enzymes that act in the small intestine are secreted by the pancreas and liver and enter the small intestine via the pancreatic duct. Pancreatic enzymes and bile from the gallbladder enter the small intestine in response to the hormone cholecystokinin, which is produced in the small intestine in response to the presence of nutrients. Secretin, another hormone produced in the small intestine, causes additional effects on the pancreas, where it promotes the release of bicarbonate into the duodenum in order to neutralize the potentially harmful acid coming from the stomach.
Ileal Interposition is a Metabolic Surgery procedure, used to treat overweight diabetic patients through surgical means. First presented by the Brazilian surgeon Aureo De Paula in 1999, this technique is applied by placing ileum, which is the distal part of the small intestine, either between stomach and the proximal part of the small intestine (1) or by placing the ileum to the proximal part of the small intestine without touching the natural connections of the stomach (2). 
There are 2 different versions of the operation. Sleeve gastrectomy procedure is standard for both of the versions.
In addition to sleeve gastrectomy procedure, a 200 cm segment of ileum is prepared while preserving the last 30 cm part of the small intestine and then ‘’interposed’’ to the proximal part of the small intestine. Thanks to this, food continue to pass throughout the entire small intestine. No malabsorption is in question in this technique, and the food is absorbed by the duodenum as well. Since negative hormones secreted from the duodenum are quite effective in the surgical treatment of diabetes, this operation offers effective weight control, but has limited effect on blood sugar control.