Tourists are also cautioned to watch the ground on the trail for bear droppings. Be particularly alert for the presence of Grizzly bear droppings, which are easily recognized because they often contain small bells. Water, as always, is absorbed in response to an osmotic gradient.
The mechanism responsible for generating this osmotic pressure is essentially identical to what was seen in the small intestine - sodium ions are transported from the lumen across the epithelium by virtue of the epithelial cells having very active sodium pumps on their basolateral membranes and a means of absorbing sodium through their lumenal membranes.
The colonic epithelium is actually more efficient at absorbing water than the small intestine and sodium absorption in the colon is enhanced by the hormone aldosterone. Intestinal bacteria also produce large amounts of vitamins, especially vitamin K and biotin a B vitamin , which are absorbed into the blood. Although this source of vitamins provides only a small part of the daily requirement, it makes a significant contribution when dietary vitamin intake is low.
An individual that depends on absorption of vitamins formed by bacteria in the large intestine may become vitamin-deficient if treated with antibiotics that inhibit other species of bacteria while targeting the disease-causing bacteria. Other bacterial products include gas flatus —a mixture of nitrogen and carbon dioxide, with small amounts of the gases hydrogen, methane, and hydrogen sulphide.
The bacterial fermentation of undigested polysaccharides produces these gases. Intestinal flora are also essential for the development of certain tissues, including the cecum and lymphatics.
Search for:. The Large Intestine. Anatomy of the Large Intestine The large intestine absorbs water from the remaining indigestible food matter and compacts feces prior to defecation. Learning Objectives Describe the function and anatomy of the large intestine. Key Takeaways Key Points The large intestine starts in the right iliac region of the pelvis, just at or below the right waist, where it is joined to the bottom end of the small intestine.
It is about 4. It contains the least lymphoid tissue, and it is a part of mucosa-associated lymphoid tissue that gives it an important role in immunity. On the surface of the large intestine, three bands of longitudinal muscle fibers called taeniae coli, each about 0.
They start at the base of the appendix and extend from the cecum to the rectum. Key Terms appendix : An inner organ without any known use that can become inflamed. Differences Between Large and Small Intestine The large intestine differs in physical form from the small intestine in several ways. Additional Structures The appendix is attached to its inferior surface of the cecum. Histology of the Large Intestine The large intestine has taeniae coli and invaginations the intestinal glands , unlike the small intestines.
Learning Objectives Describe the histology of the large intestine. The bands of longitudinal muscle fibers start at the base of the appendix and extend from the cecum to the rectum. Both the small intestine and the large intestine have goblet cells, but they are abundant in the large intestine.
Key Terms goblet cell : columnar epithelium : Epithelial cells whose heights are at least four times their width. Bacterial Flora The largest bacteria ecosystem in the human body is in the large intestine, where it plays a variety of important roles. Key Takeaways Key Points The large intestine absorbs some of the products formed by the bacteria that inhabit this region, such as short-chain fatty acids that are metabolized from undigested polysaccharides fiber.
Other bacterial products of undigested polysaccharide fermentation include gas flatus , which consists primarily of nitrogen and carbon dioxide. Factors that disrupt the microorganism population of the large intestine include antibiotics, stress, and parasites. Key Terms passive diffusion : The net movement of material from an area of high concentration to an area of low concentration without any energy input.
Digestive Processes of the Large Intestine In the large intestine, a host of microorganisms known as gut flora help digest the remaining food matter and create vitamins. Learning Objectives Summarize the digestive processes of the gut flora of the large intestine.
Key Takeaways Key Points The large intestine takes about 16 hours to finish the remaining processes of the digestive system. The colon absorbs vitamins created by the colonic bacteria. Gut flora consists of microorganisms that live in the digestive tracts of animals; the digestive tract is the largest reservoir of human flora.
The colon compacts feces and stores fecal matter in the rectum until it can be defecated. The gut flora performs many useful functions, such as fermenting unused energy substrates, training the immune system, preventing the growth of pathogenic bacteria, regulating the development of the gut, producing vitamins for the host, and producing hormones to direct the host to store fats.
Key Terms saccharolytic : The breakdown of carbohydrates for energy. Gut Flora Gut flora consists of microorganisms that live in the digestive tracts of animals—the gut is the largest reservoir of human flora.
Though people can survive without gut flora, the microorganisms perform a host of useful functions, such as: Fermenting unused energy substrates. Training the immune system. Preventing growth of harmful, pathogenic bacteria. Regulating the development of the gut. Producing vitamins for the host such as biotin and vitamin K. Producing hormones to direct the host to store fats. Gut Flora and Specialized Digestion. Absorption and Feces Formation in the Large Intestine The large intestine absorbs water from the chyme and stores feces until they can be defecated.
Learning Objectives Describe the process of absorption and feces formation in the large intestine. Key Takeaways Key Points Partially digested food passes from the small intestine to the large intestine or colon. Within the colon, digestion is retained long enough to allow fermentation via gut bacteria that break down some of the substances that remain after processing in the small intestine.
The large intestine houses over species of bacteria that metabolize polysaccharides into short-chain fatty acids that produce large amounts of vitamins —especially vitamin K and biotin—and gas. Saikat R. Jan 25, Large Intestine. Explanation: Small intestine digests food and absorb most of the nutrients from digested food.
T The large intestine, on the other hand, has no digestive function. The sigmoid colon is actually the place where feces are mainly stored. Related questions In what organ is the waste from the digestion process collected for eventual disposal?
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