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Oesophagus or food pipe
The oesophagus is a long muscular pipe that connects the buccal cavity to the stomach. Oesophagus is also termed as the food pipe.
 
It runs along the neck and the chest. It is about \(30\)\(cm\) in length. 
 
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Oesophagus
 
The food coming from the mouth moves down through the oesophagus by peristalsis
What is peristalsis?
When the food enters the oesophagus at the top end, the muscles in the wall of the oesophagus contracts and relax alternately to produce wave-like movements. This contracting and relaxing movement of the muscles of the oesophagus is called peristalsis.
 
The food is thus easily pushed down.  Peristalsis takes place throughout the alimentary canal and pushes the food downwards towards the stomach.
 
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Peristalsis
  
During vomiting, the food moves in the opposite direction, i.e. from the stomach to the mouth. The process is called anti-peristalsis in the food pipe.
Stomach
The stomach is a bag-like structure, which is thick-walled. It is a J shaped structure present on the left side of the abdomen. The stomach is the widest portion of the alimentary canal where the food is further digested. At one end, it collects food from the food pipe, and at the other, it opens into the small intestine.
 
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Stomach
 
For around \(3\)\(hrs\), the food is churned in the stomach. The food breakdown into smaller pieces, resulting in a semi-solid paste. The stomach's inner lining secretes mucous, hydrochloric acid (HCl) and digestive juices.  
  • The mucous protects the stomach's lining from the acidic environment.
  • The hydrochloric acid kills bacteria which enters along with the food from the mouth. The acid makes the medium in the stomach acidic and it is necessary for the action of the digestive juices on proteins in the stomach.
  • The lining of the stomach secretes digestive juices. This break down the proteins into simpler substances. The food that is partially digested then goes into the small intestine.
Reference:
https://commons.wikimedia.org/wiki/File:Figure_34_01_09.jpg