Flowchart Science: The Human Body: The Digestive System

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Bile is critical in the digestion of fats into free fatty acids. Bile is composed of water, salts, acids, and lipids. It is a medium in which fats and fat-soluble vitamins can dissolve and be carried into the blood stream via the villi. It normally takes about 36 hours for stool to get through the colon. The stool itself is mostly food debris and bacteria. These bacteria perform several useful functions, such as synthesizing various vitamins, processing waste products and food particles, and protecting against harmful bacteria. When the descending colon becomes full of stool, it empties its contents into the rectum to begin the process of elimination. You may think digestion begins the moment you take a bite. But in some case, it starts even before that. The sight, smell, or thought of food can be enough to trigger your salivary reflex. That’s why your mouth waters when you’re hungry. Saliva is also produced with the chewing motion. It moistens and lubricates food, making it easier to swallow. The digestive system of the human body comprises a group of organs working together to convert food into energy for the body. Anatomically, the digestive system is made up of the gastrointestinal tract, along with accessory organs such as the liver, pancreas and gallbladder. The hollow organs that make up the gastrointestinal tract (GI tract) include the mouth, stomach, oesophagus, small intestine and large intestine that contains the rectum and anus. Probiotics support the numbers of helpful microorganisms in your gut. They also aid in nutrient absorption in the small intestine and help break down your food. There is growing evidence to suggest that probiotic supplementation may play a role in supporting immune health, too.

Bile, an essential secretion of the liver, travels from the liver to the gallbladder through cystic ducts. Additionally, it can directly enter the bile duct via small liver channels. The convergence of the cystic and hepatic ducts gives rise to the common bile duct, which traverses through the pancreas before emptying into the duodenum. This duct, due to its connection with the pancreatic ducts, is often referred to as the hepatopancreatic duct. Bile also contains bilirubin, a yellow-orange pigment released by red blood cells as they break down. Your body can’t metabolize bilirubin on its own, so it relies on bacteria to help out. When the bacteria in your small intestine chow down on bilirubin, they produce a dark material called sterobilin. This by product gives stool it’s notable brown color.The large intestine’s primary function is the re-absorption of water from the remaining indigestible food matter, effectively concentrating waste before it is excreted. This process is facilitated by the numerous low longitudinal folds in the inner lining of the large intestine, which increase the surface area for water absorption. Secretin and Pancreozymin: These hormones stimulate the pancreas to release pancreatic juices into the duodenum. The layers present in the gastrointestinal system are mucous membrane (mucosa), submucosa, muscularis externa, and serosa or adventitia. The mucosa and submucosa projections enhance the surface area available for absorption. The lamina propria and submucosa possess glands.

The pancreas is an intricately branched, flattened gland, exhibiting a pale hue. It is strategically positioned in the mesentery, nestled between the stomach and the duodenum. The pancreas is connected to the common bile duct, into which its pancreatic ducts open. This connection is often referred to as the hepatopancreatic duct due to its association with both the liver and the pancreas. The stomach can be functionally divided into proximal and distal motor pumps, which stores food content and pumps chyme along the conduit, respectively. Portions of chyme are passed into the pylorus and into the small intestines. Lining: The inner lining of the buccal cavity consists of ciliated columnar epithelial cells. These cells play a role in moving mucus and trapped particles.Beta Cells: Characterized by small, rounded structures with deeply stained nuclei and orange-brown granules, these cells produce the hormone insulin. Insulin is indispensable for carbohydrate metabolism, regulating glycogen storage in muscles and the liver, maintaining blood sugar levels, and enhancing the ability of tissues to oxidize glucose for energy. Following the buccal cavity, the food moves through the pharynx and into the oesophagus, a narrow tube responsible for transporting food to the stomach. The oesophagus then leads to the stomach, where the primary digestion occurs. From the stomach, the digested food progresses into the intestine, where nutrients are absorbed. The remaining undigested food then moves into the rectum and is eventually expelled through the cloaca. At each step along the digestive journey, food is modified and broken down into usable pieces. By modeling this system step-by-step, you can gain a better understanding of the fate of your food after it enters your body. Learn the Language of Digestion

The absence of salivary glands in frogs means that lubrication of food is facilitated by mucus secreted from the lining of the bucco-pharyngeal cavity and esophagus. The food is then propelled down the esophagus by peristalsis, a wave-like contraction of the muscular wall.Subsequently, the oesophagus, a narrow tube, transports the food from the pharynx to the stomach. The oesophagus’s primary function is to serve as a conduit, moving food efficiently to the next stage of digestion without any significant digestion occurring within it. The stomach is a sac-like organ with strong muscular walls. In addition to holding food, it serves as the mixer and grinder of food. The stomach secretes acid and powerful enzymes that continue the process of breaking the food down and changing it to a consistency of liquid or paste. From there, food moves to the small intestine. Between meals, the non-liquefiable remnants are released from the stomach and ushered through the rest of the intestines to be eliminated. The end result is that these nerves send motor signals to the tongue, which moves the bolus against the hard and soft palate, then into the oropharynx (which is also under brainstem regulation). The bolus then continues inferiorly towards the laryngopharynx and the swallowing reflex is initiated at the esophagus. All the actions of swallowing up to this point were under voluntary control; however, the rest of the action is carried out by involuntary peristaltic contractions that travel in a craniocaudal fashion. At the level of the pharynx: The terminal opening of the large intestine, the anus, is guarded by a muscular structure known as the anal sphincter. This sphincter muscle maintains control over the expulsion of feces, ensuring that waste is excreted at an appropriate time.