parts of the digestive system

parts of the digestive system

• 1.
  THE PARTS OFTHE DIGESTIVE SYSTEM THE OESOPHAGUS The oesophagus is also known as the gullet or food pipe. It’s part of the digestive system, which is sometimes called the gastro-intestinal tract. The oesophagus is a long, muscular tube that connects your mouth to your stomach. When you swallow food, the walls of the oesophagus squeeze together. This moves the food down the oesophagus to the stomach. The oesophagus has four layers:  The mucosa: the inner layer, which is moist to help food pass smoothly into the stomach.  The submucosa: this contains glands that produce mucus (phlegm), which keeps the oesophagus moist.  The muscularis: the muscle layer, which pushes food down to the stomach.  The adventitia: the outer layer, which attaches the oesophagus to nearby parts of the body.
• 2.
  THE STOMACH The stomachis a muscular sac that is located on the left side of the abdominal cavity. In an average person, the stomach is about the size of their two fists placed next to each other. This major organ acts as a storage tank for food so that the body has time to digest large meals properly. The stomach also contains hydrochloric acid and digestive enzymes that continue the digestion of food that began in the mouth. The stomach has four parts:  The cardiac: is the first portion of the stomach and is where food content passes from the oesophagus into the stomach. The acids and enzymes referred to as the gastric juices are manufactured in the cardiac.  The fundus: stores undigested food and also the gases released from the chemical digestion of food.  The body of the stomach or the corpus: is the largest of the four parts that make up the stomach. And this is where the bulk of the partial digestion occurs.  The pylorus is connected to the beginning of the small intestine. The contents of the stomach move into the small intestine via the pyloric canal.
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  SMALL INTESTINE Small Intestine Thesmall intestine is part of the lower gastrointestinal tract. It is located just inferior to the stomach and takes up most of the space in the abdominal cavity. The entire small intestine is coiled like a hose and the inside surface is full of many ridges and folds. These folds are used to maximize the digestion of food and absorption of nutrients. Different parts of the small intestine:  The duodenum is the first and shortest segment of the small intestine. It receives partially digested food from the stomach and plays a vital role in the chemical digestion of chime in preparation for absorption in the small intestine.  The jejunum: jejunum is the middle segment of the small intestine found between the duodenum and the ileum. Most of the nutrients present in food are absorbed by the jejunum before being passed on to the ileum for further absorption  Ileum: ileum is the last part of the three part tube that makes up the small intestine. It is where the remaining nutrients are absorbed before moving into the large intestine.
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  LARGE INTESTINE The largeintestine is the final section of the gastrointestinal tract that performs the vital task of absorbing water and vitamins while converting digested food into faeces. Although shorter than the small intestine in length, the large intestine is considerably thicker in diameter, thus giving it its name. The ascending colon is one of the four major regions of the colon, which is itself one of the parts of our large intestine. The ascending colon carries faeces from the cecum superiorly along the right side of our abdominal cavity to the transverse colon. In the ascending colon, bacteria digest the transitory faecal matter in order to release vitamins. The descending colon is a segment of the large intestine and is the third and penultimate segment of the colon. It transports faeces from the transverse colon inferiorly along the left side of the abdominal cavity to the sigmoid colon. Faces passing through the descending colon are stored until they are ready to be eliminated from the body. The transverse colon is the longest region of the colon and is located between the ascending colon and descending colon. It is named for the fact that it crosses the abdominal cavity transversely from the right side to left side just below the stomach. Much of the absorption and faeces formation of the colon takes place in the transverse colon, making it a very important region of the digestive system.
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  RECTUM The rectum isthe concluding part of the large intestine that terminates in the anus. The average length of the human rectum may range between 10 and 15 cm. Its diameter can be compared to that of the sigmoid colon (the part of the large intestine nearest the rectum) at its onset. However, it becomes larger near the anus, where it forms the rectal ampulla. The Key role of the rectal ampulla is to act as a temporary storehouse for faeces. The expansion of the rectal walls causes the stretch receptors within the walls to stimulate the urge to defecate. If the defecation process is delayed, it may result in constipation. When the storage site becomes full, the intrarectal pressure causes the anal canal walls to dilate and expand. This results in the faeces entering the canal.
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  ANUS The anus isthe opening at the far end of the digestive tract through which stool leaves the body. The anus is formed partly from the surface layers of the body, including the skin, and partly from the intestine. The anus is lined with a continuation of the external skin. A muscular ring (anal sphincter) keeps the anus closed until the person has a bowel movement. LIVER The liver is a large, meaty organ that sits on the right side of the belly. Weighing about 3 pounds, the liver is reddish-brown in colour and feels rubbery to the touch. Normally you can't feel the liver, because it's protected by the rib cage. The liver has two large sections, called the right and the left lobes. The gallbladder sits under the liver, along with parts of the pancreas and intestines. The liver and these organs work together to digest, absorb, and process food. The liver's main job is to filter the blood coming from the digestive tract, before passing it to the rest of the body. The liver also detoxifies chemicals and metabolizes drugs. As it does so, the liver secretes bile that ends up back in the intestines. The liver also makes proteins important for blood clotting and other functions.
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  PANCREAS The pancreas isa glandular organ in the digestive systemand endocrine system of vertebrates. In humans, it is located in the abdominal cavity behind the stomach. It is an endocrine gland producing several important hormones, including insulin, glucagon and pancreatic polypeptide which circulate in the blood. The pancreas is also a digestive organ, secreting pancreatic juice containing digestive enzymes that assist digestion and absorption of nutrients in the small intestine. These enzymes help to further break down the carbohydrates, proteins, and lipids in the chime. GALL BLADDER The gallbladder is a small pouch that sits just under the liver. The gallbladder stores bile produced by the liver. After meals, the gallbladder is empty and flat, like a deflated balloon. Before a meal, the gallbladder may be full of bile and about the size of a small pear. In
• 8.
  response to signals,the gallbladder squeezes stored bile into the small intestine through a series of tubes called ducts. Bile helps digest fats, but the gallbladder itself is not essential. Removing the gallbladder in an otherwise healthy individual typically causes no observable problems with health or digestion yet there may be a small risk of diarrhoea and fat malabsorption .