|
The esophagus is about 10 inches in length.
Each end of it is closed off by a ring of muscle (sphincter). At the top
end, is the upper esophageal sphincter (UES), while at the bottom
is the lower esophageal sphincter (LES), also known as the gastroesophageal
junction, cardiac valve, or cardia. Usually, the UES
remains closed. However, when food enters the back of the throat the spincter
muscle relaxes and opens, allowing the food to enter the esophagus. The
UES then closes to prevent regurgitation into the throat. The esophagus
is lined with a protective mucous membrane and its walls are lined with
muscles that slowly squeeze the food through the esophageal passage -
a process known as peristalsis. When food reaches the end of the
esophagus, the LES opens to allow food to pass through into the stomach,
then closes to stop food or acidic gastric juice from the stomach
from backing up. If either of these sphincters malfunctions, it can lead
to a variety of digestive or gastric conditions, including achalasia,
heartburn and gastroesophageal reflux disease (GERD). It
takes about 2-3 seconds for food to pass through the esophagus and enter
the stomach.
NEXT: How
Food Is Digested In The Stomach.
|