Question

What is the name of the first part of the small intestine? What controls the entry of food into the first part of the small intestine?

Answer 1

Hint: The small intestine is an organ present in the alimentary canal of the body that absorbs nutrients through food. The absorption of food occurs through the small finger-like projections found in the small intestine called villi.

Complete answer:
The first part of the small intestine is the duodenum. The small intestine consists of three parts that include the duodenum, jejunum, and the ileum. The duodenum is the shortest part where the finger-like projection called villi are present, these villi help in the absorption of food and nutrients. The food is taken from the mouth to the esophagus and then is carried to the stomach and then to the small intestine where most of the digestion takes place. The unidirectional flow of chyme (partially digested food along with stomach juices) from the stomach to the duodenum is overlooked by the pyloric sphincter. This ring of smooth muscles allows chyme to move out from the stomach only when it experiences peristaltic pressure (contractions) from the fundic and body region of the stomach indicating that the food has been appropriately mixed with the acids. The pyloric sphincter acts as a guard and allows the chyme to pass on to the duodenum bit by bit.
As all the chyme moves to the duodenum, the pressure in the latter increases due to peristalsis, forcing the pyloric sphincter shut. This does not allow the movement of intestinal juices into the stomach.

Note:
Though the pyloric sphincter is a small mass of smooth muscle, its malfunctioning can cause problems like Bile reflux, which is similar to acid reflux, and Gastroparesis, which causes difficulty in emptying the stomach.