Digestive System Vocabulary Terms Anus : located at the end of the digestive system. The function of the anus is to expel feces, and unwanted semi-solid material produced during digestion. Appendix : a pouch like structure of the colon.
The appendix is located near the junction of the small and large intestines. It is often referred to as the vermiform appendix or cecal appendix. The appendix is thought to be a vestigial structure in humans an organ that has lost its original function.
Today the appendix is prone to infection is often removed at the first sign of a problem. Ascending Colon : The large intestine can be divided up into different regions. The first section that takes digested material up is the ascending colon. It is smaller in caliber than the cecum, with which it is contiguous. Bile : yellowish, blue and green fluid secreted from the liver. Bile is sometimes called gall and is stored in the gallbladder between meals. It is secreted into the duodenum to aid int eh process of digestion of lipids via emulsification.
Cecum : the beginning of the large intestine. The cecum is a pouch that connects the ileum with eh ascending colon. Chyme : the name given to the partially digested food that leaves the stomach via the pyloric valve into the small intestine duodenum.
Chyme, also known as chymus has the consistency of oatmeal. Descending Colon : the region of the large intestine that moves digested material downward through the left hypochondrium and lumbar regions.
Duodenum : the first section of the small intestine. This hollow, jointed tube is only about inches long. It connects the stomach to the jejunum and is where most of the chemical digestion takes place. Epiglottis : a small flap of elastic cartilage just below the pharynx that helps direct food down the esophogus and direct air into the lungs.
Without the epiglottis, it would be difficult to Esophagus : a muscular tube that allows food to pass from the pharynx to the stomach. Through peristalsis the esophagus is able to push food from the pharynx to the stomach, even if the individual is standing on their head. Gall Bladder : a small organ that stores bile produced in the liver. It can hold about 50 mL of bile. Ileum : the last region of the small intestine. The ileum follows the other small intestine regions known as the duodenum and the jejunum.
After the ileum, digestive material must pass through the ileocecal valve to get to the cecum. Jejunum : the middle section of the small intestine. It is preceded by the duodenum and followed by the ileum.
Liver : a vital organ that produces chemicals necessary for digestion. In digestion it is extremely important in producing bile, which helps break down fats. Mouth : Often considered the first step in the digestive process. The chewing action of the mouth serves to mechanically break down food particles. Saliva produced here helps in chemical breakdown of food. Pancreas : an organ that aids in both the digestive system and the endocrine system. It aids in the digestive system by producing pancreatic juices, which contain digestive enzymes, which pass through the small intestine.
These juices help break down carbohydrates, protien and fat in the chyme. Peristalsis : a radially symmetrical contraction of muscles that propagate down a tube.
It occurs especially in the esophagus and the stomach. The chemical process of digestion begins during chewing as food mixes with saliva, produced by the salivary glands Figure Saliva contains mucus that moistens food and buffers the pH of the food. Saliva also contains lysozyme, which has antibacterial action. It also contains an enzyme called salivary amylase that begins the process of converting starches in the food into a disaccharide called maltose.
Another enzyme called lipase is produced by cells in the tongue to break down fats. The chewing and wetting action provided by the teeth and saliva prepare the food into a mass called the bolus for swallowing. The tongue helps in swallowing—moving the bolus from the mouth into the pharynx. The pharynx opens to two passageways: the esophagus and the trachea. The esophagus leads to the stomach and the trachea leads to the lungs. The epiglottis is a flap of tissue that covers the tracheal opening during swallowing to prevent food from entering the lungs.
Esophagus The esophagus is a tubular organ that connects the mouth to the stomach. The chewed and softened food passes through the esophagus after being swallowed. The smooth muscles of the esophagus undergo peristalsis that pushes the food toward the stomach. The peristaltic wave is unidirectional—it moves food from the mouth to the stomach, and reverse movement is not possible, except in the case of the vomit reflex. The peristaltic movement of the esophagus is an involuntary reflex; it takes place in response to the act of swallowing.
Ring-like muscles called sphincters form valves in the digestive system. The gastro-esophageal sphincter or cardiac sphincter is located at the stomach end of the esophagus. In response to swallowing and the pressure exerted by the bolus of food, this sphincter opens, and the bolus enters the stomach. When there is no swallowing action, this sphincter is shut and prevents the contents of the stomach from traveling up the esophagus.
A large part of protein digestion occurs in the stomach Figure The stomach is a saclike organ that secretes gastric digestive juices. Protein digestion is carried out by an enzyme called pepsin in the stomach chamber. The highly acidic environment kills many microorganisms in the food and, combined with the action of the enzyme pepsin, results in the catabolism of protein in the food. Chemical digestion is facilitated by the churning action of the stomach caused by contraction and relaxation of smooth muscles.
The partially digested food and gastric juice mixture is called chyme. Gastric emptying occurs within two to six hours after a meal. Only a small amount of chyme is released into the small intestine at a time.
The movement of chyme from the stomach into the small intestine is regulated by hormones, stomach distension and muscular reflexes that influence the pyloric sphincter. The stomach lining is unaffected by pepsin and the acidity because pepsin is released in an inactive form and the stomach has a thick mucus lining that protects the underlying tissue.
Chyme moves from the stomach to the small intestine. The small intestine is the organ where the digestion of protein, fats, and carbohydrates is completed. The small intestine is a long tube-like organ with a highly folded surface containing finger-like projections called the villi. The top surface of each villus has many microscopic projections called microvilli. The epithelial cells of these structures absorb nutrients from the digested food and release them to the bloodstream on the other side.
The villi and microvilli, with their many folds, increase the surface area of the small intestine and increase absorption efficiency of the nutrients. The human small intestine is over 6 m The duodenum is separated from the stomach by the pyloric sphincter. The stomach muscles churn and mix the food with digestive juices that have acids and enzymes, breaking it into much smaller, digestible pieces. An acidic environment is needed for the digestion that takes place in the stomach.
By the time food is ready to leave the stomach, it has been processed into a thick liquid called chyme pronounced: kime. A walnut-sized muscular valve at the outlet of the stomach called the pylorus pronounced: pie-LOR-us keeps chyme in the stomach until it reaches the right consistency to pass into the small intestine.
Chyme is then squirted down into the small intestine, where digestion of food continues so the body can absorb the nutrients into the bloodstream. The inner wall of the small intestine is covered with millions of microscopic, finger-like projections called villi pronounced: VIH-lie.
The villi are the vehicles through which nutrients can be absorbed into the blood. The blood then brings these nutrients to the rest of the body. The liver under the ribcage in the right upper part of the abdomen , the gallbladder hidden just below the liver , and the pancreas beneath the stomach are not part of the alimentary canal, but these organs are essential to digestion. The liver makes bile , which helps the body absorb fat. Bile is stored in the gallbladder until it is needed.
The pancreas makes enzymes that help digest proteins, fats, and carbs. It also makes a substance that neutralizes stomach acid. Select basic ads. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. The duodenum, the first and shortest section of the small intestine, is a key organ in the digestive system.
Together, the duodenum and other organs of the alimentary canal the pathway by which food enters the body and solid wastes are expelled form the digestive system of the body. The duodenum has been described as a C-shaped or horseshoe-shaped segment of the small intestine.
It is located below the stomach. This portion of the small intestine received its name due to its size; in Latin, duodenum translates to 12 fingers, which is the approximate length of the organ. Each segment has a different anatomy shape and performs a different based function. The lining of the duodenum is comprised of four layers—each with its own specialized function. The duodenum measures approximately 20 to 25 centimeters approximately 8 to 10 inches in length compared to the jejunum, which is approximately 2.
The duodenum also connects to the liver via a structure called the hepatoduodenal ligament. This junction is where the duodenum receives bile to mix with chyme, an important part of the chemical digestive process described in more detail below. Segments of the Duodenum. Layers of the Duodenum. The walls of the duodenum are comprised of four layers:. The small intestine is located below the stomach. The small intestine is comprised of the duodenum, the jejunum, and the ileum. The duodenum is connected to the stomach at its proximal toward the beginning end.
It is connected to the middle section of the small intestine, called the jejunum at its distal located away from a specific area end. Collectively—in addition to the esophagus —the stomach, large intestine, and accessory organs such as the liver and pancreas , along with the duodenum and the other two sections of the small intestine form what is commonly referred to as the gastrointestinal tract or GI tract.
Duodenal atresia also called duodenal stenosis is a rare congenital present at birth disorder of the duodenum.
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