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Pyloric Sphincter: Location, Structure, and Function

Praseeda Shirodkar
Pyloric sphincter, an important part of the digestive system, opens and closes to allow or restrict the entry of food into the duodenum. Its proper functioning is crucial to the process of digestion. This story provides some information about the same, with the help of a diagram.
It is the physical and chemical composition of the meal that decides the rate at which the stomach is emptied. Fluids are known to empty faster than solids, carbohydrates faster than proteins, and proteins faster than fats.
The human digestive system has different parts which function together in the right manner, so as to maintain the digestive and overall health of an individual. The pyloric sphincter, a muscular tube in the shape of a walnut, situated at the stomach outlet, is one important part of the digestive system.
What is the pyloric sphincter? Where is it located? What are its functions? Read on to find this and more.
The pyloric sphincter is a sphincter muscle of the pylorus, a small circular opening between the stomach and the duodenum. It can also be referred to as a tough ring of smooth muscle that allows the entry of food into the small intestine.
It allows the entry or restricts food from passing through it by remaining open or closed. For two-thirds of the time, it remains open, allowing food to pass into the duodenum.
The pylorus (also known as pyloric part) has two parts, namely the pyloric antrum and the pyloric canal. The pyloric sphincter is located at the end of the pyloric canal which is the opening to the duodenum. It is the thickening of the circular layer of fibers in this canal that forms the pyloric sphincter.


The structure of the pyloric sphincter can be easily understood with the help of a labeled diagram, as shown below.


The pyloric sphincter carries out functions that are essential for the proper functioning of the human digestive system. They are as follows:
On being contracted, it holds the food in the stomach which is then broken down by the digestive juices into chyme (partially digested food in semi-liquid form). The sphincter relaxes or opens as soon as this is done, thus allowing the chyme to enter the duodenum and the digestion process continues. 
This chyme leaves the stomach in small squirts and not all at one time. More nutrients can be absorbed by the body when the food spends more time in the stomach. In this way, it regulates digestion.
On tightening after the chyme has passed, it helps in preventing the backflow or reflux of this broken down food back into the stomach. In short, it prevents regurgitation from the intestines back into the stomach. Thus, it prevents this problem which otherwise could have been painful. Moreover, a healthy sphincter makes sure that the contents of the digestive tract move in a single direction.

Associated Health Problems

A problem in the functioning of this valve can lead to serious complications. One such condition that could arise is pyloric stenosis wherein the valve is narrowed, making it difficult for the chyme to pass through. The valve can also interrupt the process of digestion by opening improperly or at the wrong time.
Those with stomach cancer usually experience blockages in the pylorus, however, there are other conditions that can cause the same problem.
If one is affected by problems related to the digestive system, he/she should visit the doctor who would conduct a series of tests to check whether it is due to a problem with the functioning of the pyloric sphincter. Techniques such as medical imaging and endoscopy prove beneficial to make definite conclusions.
The treatment would vary depending on the overall health of the patient and the cause of the problem. While pyloric stenosis can be treated with the help of medications, surgery is needed to remove cancerous growths.
Immediate medical intervention is a must when any health problems arise, so as to rule out the possibility of any further complications.