Components Historical depiction of the digestive system, 17th century Persia There are several organs and other components involved in the digestion of food. The organs known as the accessory digestive glands are the livergall bladder and pancreas. Other components include the mouthsalivary glandstongueteeth and epiglottis.
Esophagus The esophaguswhich passes food from the pharynx to the stomach, is about 25 cm 10 inches in length; the width varies from 1. The esophagus lies behind the trachea and heart and in front of the spinal column ; it passes through the diaphragm before entering the stomach.
The esophagus contains four layers—the mucosa, submucosa, muscularis, and tunica adventitia. The mucosa is made up of stratified squamous epithelium containing numerous mucous glands. The submucosa is a thick, loose fibrous layer connecting the mucosa to the muscularis.
Together the mucosa and submucosa form long longitudinal folds, so that a cross section of the esophagus opening would be star-shaped. The muscularis is composed of an inner layer, in which the fibres are circular, and an outer layer of longitudinal fibres.
Both muscle groups are wound around and along the alimentary tractbut the inner one has a very tight spiral, so that the windings are virtually circular, whereas the outer one has a very slowly unwinding spiral that is virtually longitudinal.
The outer layer of the esophagus, the tunica adventitiais composed of loose fibrous tissue that connects the esophagus with neighbouring structures. Except during the act of swallowingthe esophagus is normally empty, and its lumen, or channel, is essentially closed by the longitudinal folds of the mucosal and submucosal layers.
The upper third of the esophagus is composed of striated voluntary muscle. The middle third is a mixture of striated and smooth involuntary muscle, and the lower third consists only of smooth muscle. The esophagus has two sphincters, circular muscles that act like drawstrings in closing channels.
Both sphincters normally remain closed except during the act of swallowing. The upper esophageal sphincter is located at the level of the cricoid cartilage a single ringlike cartilage forming the lower part of the larynx wall.
This sphincter is called the cricopharyngeus muscle.
The lower esophageal sphincter encircles the 3 to 4 cm of the esophagus that pass through an opening in the diaphragm called the diaphragmatic hiatus.
The lower esophageal sphincter is maintained in tension at all times, except in response to a descending contraction wave, at which point it relaxes momentarily to allow the release of gas belching or vomiting. The lower esophageal sphincter has an important role, therefore, in protecting the esophagus from the reflux of gastric contents with changes in body position or with alterations of intragastric pressure.
Transport through the esophagus is accomplished by the primary esophageal peristaltic contractions, which, as noted above, originate in the pharynx. These contractions are produced by an advancing peristaltic wave that creates a pressure gradient and sweeps the bolus ahead of it.
Transport of material through the esophagus takes approximately 10 seconds. When the bolus arrives at the junction with the stomach, the lower esophageal sphincter relaxes and the bolus enters the stomach.The digestive system is a pretty important part of your body.
Without it, you couldn't get the nutrients you need to grow properly and stay healthy. And next time you sit down to lunch, you'll know where your food goes — from start to finish! The human digestive system is a complex series of organs and glands that processes food. In order to use the food we eat, our body has to break the food down into smaller molecules that it can process; it also has to excrete waste.
The digestive system is a pretty important part of your body.
Without it, you couldn't get the nutrients you need to grow properly and stay healthy. And next time you sit down to lunch, you'll know where your food goes — from start to finish! The esophagus is what connects the throat to the stomach.
This is what brings the food into the digestive system. Needless to say, this is completely necessary to survive because there would be no place for food to enter the digestive system without it. The esophagus is a muscular tube connecting the throat (pharynx) with the stomach.
The esophagus is about 8 inches long, and is lined by moist pink tissue called mucosa. The esophagus runs behind.
Human digestive system - Esophagus: The esophagus, which passes food from the pharynx to the stomach, is about 25 cm (10 inches) in length; the width varies from to 2 cm (about 1 inch). The esophagus lies behind the trachea and heart and in front of the spinal column; it passes through the diaphragm before entering the stomach.
The esophagus contains four layers—the mucosa, .