The function of the pharynx , the esophagus and the stomach in the digestive system
The pharynx is a cavity extending from the mouth to the esophagus , It is a common cavity between the esophagus and the trachea , the pharynx is a common cavity between the digestive system and the conducting zone of the respiratory system .
The conducting zone includes the nose , the larynx , the trachea , the bronchi and the bronchioles , and their function is to filter , warm and moisten the air and conduct it into the lungs .
The human pharynx is divided into three sections which are the nasophaynx , the oropharynx and the laryngopharynx .
The esophagus is a muscular tube connecting to the stomach , and it allows the food to pass from the mouth to the stomach , The esophagus is usually from 18 t0 25 centimetres ( cm ) long , And it is behind the trachea and the heart, It passes through the diaphragm .
The esophagus empties into the cardia of the stomach , And during the swallowing the epiglottis prevents the food from going down the larynx .
The stomach is sac-like muscular organ , And it is a hollow , dilated part of the digestive system which located on the left side of the upper abdomen .
The stomach is located between the esophagus and the small intestine , And it has a relaxed near empty volume of about 45 to 75 millilitres , and it normally expands to hold about one litre of food .
The stomach secretes the gastric juice that makes the incomplete digestion of the proteins , The stomach receives the food from the esophagus , and enters the stomach through a muscular valve called the lower esophageal sphincter .
The stomach mixes the food by its gastric ( digestive ) juice to form a semi- liquid substance after few hours that can be digested easily , The stomach is divided into four sections beginning at the cardia , and each of them has different cells and functions .
The cardia is where the contents of the esophagus empty into the stomach , and the cardia is defined as the region following the z-line of the gastroesophageal junction .
The fundus is formed by the upper curvature of the stomach , the body is the main central region and the pylorus is the lower section of the stomach that facilitates emptying the contents into the small intestine .