Differences in Small & Large Intestines | Children's Pittsburgh
Food and the products of digestion pass through the intestine, which is divided into two sections called the small intestine and the large intestine. They jejunum is the largest section of the small intestine. 5 Large Intestine; 6 Accessory Digestive Organs and Glands Where the esophagus meets the stomach there is a ring-like muscle known as the cardiac sphincter. The word intestine is derived from a Latin root meaning “internal,” and indeed, the two organs together nearly fill the interior of the abdominal cavity. In addition .
The food, now chyme, enters from the stomach into the duodenum where it is mixed together with the bile and other digestive juices produced by the accessory digestive organs and drained into the duodenum.
Absorption of food also begins here with the absorption of vitamins, minerals and other nutrients. In particular, before the food passes into the next part of the small intestine iron, calcium and magnesium are absorbed here. The rest of the food is passed into the jejunum. Jejunum Function The second middle section of the small intestine is a coiled tube which is thicker and more vascular than the ileum. It lies in the belly button area of the abdomen. There are small fingerlike projections in the wall of the jejunum called villi.
These villi are covered with smaller projections called microvilli. The villi increase the surface area of the jejunum and allows much more absorption of nutrients in this part of the small intestine—most of the food absorption is done in this part of the digestive tract. Simple sugars, water soluble vitamins except vitamin C and some Bs and amino acids made from the food is passed from the villi into the blood stream while the fat is passed into the lymph capillaries.
The rest of the food passes into the ileum. Ileum The last part of the small intestine is mainly the pelvic region. It looks very similar to the jejunum. However, the nature of the small intestine gradually changes.
Small intestine - Wikipedia
It is thinner and has fewer blood vessels as compared to the jejunum. The last absorption of nutrients from the food takes place here—amino acids the end products of protein digestionfat-soluble vitamins A, D, E, and Kfatty acids the end products of fat digestioncholesterol, sodium, potassium alcohol, and B The terminal ileum is an important part as this is where vitamin B12 is absorbed into the blood capillaries.
The unabsorbed and undigested food then passes from the ileum into the cecum, the beginning of the large intestine. This food residue is full of bacteria. Large Intestine Large Intestine — Click for larger image The large intestine forms the last part of the digestive tract, which is about 5 feet long and wider than the small intestine.
The surface area on the inside of the large intestine is smaller than the small intestine. The large intestine can be divided into the cecum, colon and rectum.Small intestine (anatomy)
The undigestible food waste passes from the small intestine into the cecum which then passes into the colon further divided into ascending colon, transverse colon, descending colon and sigmoid colon where the fluids and salts are absorbed.
The undigested food moves up the ascending colon, across the transverse colon, down the descending colon and into the rectum. The colon soaks up to 50 fluid ounces of water every day. After absorption, the remaining undigested matter is squeezed into a bundle called feces. Feces is made of fiber, undigested food, cells that slough off the lining of the intestines and bacteria. They make vitamin K and B12 which is absorbed by the colon wall, break down amino acids and make nitrogen, live off of fiber which makes gas.
When the bacteria finish with the feces, it is passed into the rectum, where it is stored until it is passed out through the anus as a bowel movement. The anus has voluntary and involuntary sphincter muscles which can tell the difference between gas and solid contents.
A vestigial organ an organ that had a purpose in the past but is now useless or close to itthe appendix, is attached to the large intestine at the cecum.
Though this organ is potentially of no use, it can cause pains and complications once it gets inflamed, a disorder called appendicitis. Accessory Digestive Organs and Glands Though not directly part of the digestive tract, the accessory digestive organs play a major role in digestion.
The accessory digestive organs include the salivary glands, pancreas, liver and gallbladder. Glands are organs that secrete hormones. Salivary Glands There are three pairs of salivary glands: It also helps break down starches in the food.
Pancreas A carrot-shaped gland located behind and under the stomach, the pancreas acts both as an endocrine gland and an exocrine gland. From the exocrine part it secretes pancreatic enzymes amylase and lipase which pass through the pancreatic duct into the small intestine the duodenum. The pancreatic duct joins the bile duct. These enzymes aid in the further breakdown of food, mainly the carbohydrate, protein and lipid part of the food. From the endocrine part it secretes insulin and glucagon.
Insulin enables you to digest and metabolize carbohydrates. The pancreas also secretes an antacid to help settle an upset stomach. It is the largest organ of the human body and is below the diaphragm in the upper epigastric region of the abdomen. It has many functions including production of chemicals necessary for digestion, synthesis of protein and detoxification.
The major function of the liver is to produce bile yellowish-green fluid which aids in the digestion and absorption of fats.
Small Intestine Disorders
It also stores glucose, iron and vitamins A, B12, D etc. The liver also sends out the nutrients and substances digested from the food to the cells of the body. Gallbladder The gallbladder is a small organ located just below the liver. It is about 3 inches long and shaped like a hollow balloon. Brush border enzymes take over from there.
The most important brush border enzymes are dextrinase and glucoamylase, which further break down oligosaccharides.
Other brush border enzymes are maltase, sucrase and lactase. Lactase is absent in some adult humans and, for them, lactose a disaccharideas well as most polysaccharides, is not digested in the small intestine.
Some carbohydrates, such as celluloseare not digested at all, despite being made of multiple glucose units. This is because the cellulose is made out of beta-glucose, making the inter-monosaccharidal bindings different from the ones present in starch, which consists of alpha-glucose. Humans lack the enzyme for splitting the beta-glucose-bonds, something reserved for herbivores and bacteria from the large intestine.
Absorption[ edit ] Digested food is now able to pass into the blood vessels in the wall of the intestine through either diffusion or active transport. The small intestine is the site where most of the nutrients from ingested food are absorbed.
The inner wall, or mucosa, of the small intestine is lined with simple columnar epithelial tissue. Structurally, the mucosa is covered in wrinkles or folds called plicae circulareswhich are considered permanent features in the wall of the organ.
They are distinct from rugae which are considered non-permanent or temporary allowing for distention and contraction. From the plicae circulares project microscopic finger-like pieces of tissue called villi Latin for "shaggy hair". The individual epithelial cells also have finger-like projections known as microvilli.
The functions of the plicae circulares, the villi, and the microvilli are to increase the amount of surface area available for the absorption of nutrientsand to limit the loss of said nutrients to intestinal fauna. Each villus has a network of capillaries and fine lymphatic vessels called lacteals close to its surface. 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: 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. The middle section of the small intestine carries food through rapidly, with wave-like muscle contractions, towards the 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. By the time food reaches your small intestine, it has already been broken up and mashed into liquid by your stomach.
Jejunum's Function in the Small Intestine and Digestive System:
Each day, your small intestine receives between one and three gallons or six to twelve liters of this liquid. The small intestine carries out most of the digestive process, absorbing almost all of the nutrients you get from foods into your bloodstream.
The walls of the small intestine make digestive juices, or enzymes, that work together with enzymes from the liver and pancreas to do this.
How can the small intestine digest so much? Looking at the small intestine as a pipe, it seems hard to believe that an organ so narrow could do such a big job.
However, looks can be deceiving. The absorptive surface area of the small intestine is actually about square meters almost 2, square feet — the size of a tennis court! How is this possible? The small intestine has three features which allow it to have such a huge absorptive surface area packed into a relatively small space: