The stomach is known to be a very significant organ of the digestive system. It is a muscular organ that is the dilated part of the digestive tract where food is primarily digested. Stomach is the one involved in the second phase of the digestion right after the chewing of food or the process of mastication. The location of the stomach is between the esophagus and the small intestine. Whenever the food reaches the stomach, certain enzymes and acids are released to aid in digestion. This involves the peristalsis or movement of food contents throughout the digestive tract. Smooth segmentations on the walls of the stomach are responsible for the release of such enzymes and they facilitate partial digestion before the food is transported to its next stop which is the small intestines.
The Digestive Process
Once you take in food, you first chew it in your mouth and this process is known as mastication. Once you are already done with chewing, the food is now known as bolus. The bolus is eventually passed to the esophagus by means of muscular movements known as peristalsis. The bolus eventually reaches the stomach and once it is already there, the stomach releases different enzymes like pepsin and also hydrochloric acid. These enzymes and acids are used to kill the microorganisms that might be present in food. The wall of the stomach churns the food by means of muscular contractions. The fundus or body of the stomach mixes the food contents and from bolus, it is eventually turned into chyme which means partially digested food. This chyme is eventually passed through the pyrloric sphincter of the stomach then it will go to the initial part of the intestine known as the duodenum. In the duodenum, the nutrients from the food are eventually absorbed by the body. Usually the time that it takes for the food to be turned into chyme is about forty minutes to about several hours depending upon the amount of food you take.
The Anatomy Of The Stomach
As what have been stated, the stomach is located between the esophagus and the upper part of the small intestine known as the duodenum. The stomach is located on the left upper quadrant of the abdomen where it lies above the diaphragm. The pancreas can be found behind the stomach as well. The upper and lower borders of the stomach are usually marked by sphincters which ensure that the contents of the stomach are well stored. These two sphincters are known as the esophageal sphincter and the pyloric sphincter located in the upper and lower borders of the stomach respectively.
The stomach, like most organs, is well supplied by nerves and blood vessels. It is surrounded by stimulant and inhibitory plexuses or groups and networks of nerves and blood vessels. These ensure that the stomach receives the adequate supply it needs for it to be able to maintain normal functioning. These also regulate the different secretory activity within the said organ together with the muscular movements of the organ.
The stomach is usually relaxed and distended with the empty volume of around 40 to 59 ml. Once food enters it, it has the ability to expand and distend thus being capable of holding food. Usually, the food content that can be stored in the stomach can reach a maximum amount of about two to three liters of food products. This is the usual capacity for adults. When it comes to children, the usual stomach capacity is about 30 ml.
Parts Of The Stomach
The stomach can be divided into four parts which have their respective functions. These four parts are known as the cardia, the fundus, the body or the corpus and lastly, the pylorus. The cardia is the initial part of the stomach where the food contents passing from the esophagus usually empties. The next part is the fundus which forms the upper curved part of the stomach. The body or corpus of the stomach is considered to be its main or central part where the food contents are partially digested. Lastly, the pylorus is known to be the lowest portion of the stomach which transports or transfers the food contents to the small intestine.
Blood Supply Of The Stomach
The stomach is properly supplied with the right amount of blood for it to function very well. The lesser curved part of the stomach is given appropriate blood supply by the gastric arteries. The right gastric one supplies the inferior or lower part while the left gastric one supplies the upper or the superior part. The greater curved part of the stomach is given adequate blood supply by the gastroepiploic arteries. On the other hand, the fundus part of the stomach is supplied properly by the short gastric artery.
Layers Of The Stomach
The stomach is also composed of different layers of tissue like that of the other organs. First of all the main layer of the stomach is known as the mucosa. It is made up of the joint lamina propria and the epithelium. These two are separated by a muscularis mucosa that serves as the smooth muscle facilitating its motion. The next layer is known as the submucosa which is found over the mucosa and is made up of fibrous connective tissue. This layer is where the Meissner’s plexus can be found.
The next layer is known as the muscularis externa which is made up of three layers of smooth muscles which are known as the inner oblique layer, then middle or medial circular layer and lastly, the outer longitudinal layer. Above the muscularis externa is the last layer known as the serosa which is considered to be continuing towards the peritoneum. These are the different layers that make up the stomach.
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