How long is the long and short intestine

In humans, the small intestine is about 6 meters or 20 feet long and the large intestine is about 1. The gastrointestinal tracts of the Chimpanzee, Orangutan, and adult human and a human fetus were studied and compared by Stevens and Hume in The chimpanzee intestines showed a longer appendix, a much lower number of loops in the small intestine, and the large intestine had increased haustrations, as compared to humans.

It is thought that reduction of the gut is a function of the higher-quality, easier to digest i. It has also been suggested that cooking, which breaks down plants fiber cellulose and lignin and connective tissue in meat collagen allowed early humans to extract more nutrients from foodstuff with less digestive effort, thus also contributing to an evolutionary reduction in shortening of energetically expensive gut tissue.

Timing of appearance of the difference in the Hominin Lineage as a defined date or a lineage separation event. What Is the Small Intestine? The small intestine is made up of three segments, which form a passage from your stomach the opening between your stomach and small intestine is called the pylorus to your large intestine: Duodenum: This short section is the part of the small intestine that takes in semi-digested food from your stomach through the pylorus, and continues the digestion process.

The duodenum also uses bile from your gallbladder, liver, and pancreas to help digest food. Jejunum: The middle section of the small intestine carries food through rapidly, with wave-like muscle contractions, towards the ileum. Ileum: This last section is the longest part of your small intestine. The ileum is where most of the nutrients from your food are absorbed before emptying into the large intestine. How can the small intestine digest so much? The small intestine has three features which allow it to have such a huge absorptive surface area packed into a relatively small space: Mucosal folds: The inner surface of the small intestine is not flat, but thrown into circular folds.

This not only increases the surface area, but helps regulate the flow of digested food through your intestine. Villi: The folds form numerous tiny projections which stick out into the open space inside your small intestine or lumen , and are covered with cells that help absorb nutrients from the food that passes through.

Microvilli: The cells on the villi are packed full of tiny hairlike structures called microvilli. This helps increase the surface of each individual cell, meaning that each cell can absorb more nutrients. What Is the Large Intestine? The large intestine is made up of the following parts: Cecum: This first section of your large intestine looks like a pouch, about two inches long.

It takes in digested liquid from the ileum and passes it on to the colon. Colon: This is the major section of the large intestine; you may have heard people talk about the colon on its own.

The colon is also the principal place for water reabsorption, and absorbs salts when needed. The colon consists of four parts: Ascending colon: Using muscle contractions, this part of the colon pushes any undigested debris up from the cecum to a location just under the right lower end of the liver. These valves help separate the feces from gas to prevent the simultaneous passage of feces and gas. Finally, food residue reaches the last part of the large intestine, the anal canal, which is located in the perineum, completely outside of the abdominopelvic cavity.

This 3. The anal canal includes two sphincters. The internal anal sphincter is made of smooth muscle, and its contractions are involuntary. The external anal sphincter is made of skeletal muscle, which is under voluntary control. Except when defecating, both usually remain closed. Three features are unique to the large intestine: teniae coli, haustra, and epiploic appendages [link].

The teniae coli are three bands of smooth muscle that make up the longitudinal muscle layer of the muscularis of the large intestine, except at its terminal end. Attached to the teniae coli are small, fat-filled sacs of visceral peritoneum called epiploic appendages. The purpose of these is unknown.

Although the rectum and anal canal have neither teniae coli nor haustra, they do have well-developed layers of muscularis that create the strong contractions needed for defecation.

The stratified squamous epithelial mucosa of the anal canal connects to the skin on the outside of the anus. This mucosa varies considerably from that of the rest of the colon to accommodate the high level of abrasion as feces pass through. Two superficial venous plexuses are found in the anal canal: one within the anal columns and one at the anus.

Depressions between the anal columns, each called an anal sinus, secrete mucus that facilitates defecation. The pectinate line or dentate line is a horizontal, jagged band that runs circumferentially just below the level of the anal sinuses, and represents the junction between the hindgut and external skin.

The mucosa above this line is fairly insensitive, whereas the area below is very sensitive. The resulting difference in pain threshold is due to the fact that the upper region is innervated by visceral sensory fibers, and the lower region is innervated by somatic sensory fibers. Most bacteria that enter the alimentary canal are killed by lysozyme, defensins, HCl, or protein-digesting enzymes. However, trillions of bacteria live within the large intestine and are referred to as the bacterial flora.

Most of the more than species of these bacteria are nonpathogenic commensal organisms that cause no harm as long as they stay in the gut lumen. In fact, many facilitate chemical digestion and absorption, and some synthesize certain vitamins, mainly biotin, pantothenic acid, and vitamin K. Some are linked to increased immune response. A refined system prevents these bacteria from crossing the mucosal barrier. Dendritic cells open the tight junctions between epithelial cells and extend probes into the lumen to evaluate the microbial antigens.

The dendritic cells with antigens then travel to neighboring lymphoid follicles in the mucosa where T cells inspect for antigens. This process triggers an IgA-mediated response, if warranted, in the lumen that blocks the commensal organisms from infiltrating the mucosa and setting off a far greater, widespread systematic reaction. The residue of chyme that enters the large intestine contains few nutrients except water, which is reabsorbed as the residue lingers in the large intestine, typically for 12 to 24 hours.

Thus, it may not surprise you that the large intestine can be completely removed without significantly affecting digestive functioning. For example, in severe cases of inflammatory bowel disease, the large intestine can be removed by a procedure known as a colectomy. Often, a new fecal pouch can be crafted from the small intestine and sutured to the anus, but if not, an ileostomy can be created by bringing the distal ileum through the abdominal wall, allowing the watery chyme to be collected in a bag-like adhesive appliance.

In the large intestine, mechanical digestion begins when chyme moves from the ileum into the cecum, an activity regulated by the ileocecal sphincter. Right after you eat, peristalsis in the ileum forces chyme into the cecum. When the cecum is distended with chyme, contractions of the ileocecal sphincter strengthen. Once chyme enters the cecum, colon movements begin.

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