Page 28 - E-book Digestive System

3. Stomach
The stomach (ventricle) is a muscular organ located on the left side of the
upper abdomen. The stomach receives food from the esophagus. When food
reaches the end of the esophagus, it enters the stomach through a muscular valve
called the lower esophageal valve. The stomach secretes acids and enzymes that
digest food. The stomach is composed of 3 parts, namely:
a.Cardiac, there is a cardiac sphincter muscle that will open if there is one
incoming food.
b. Fundus, is the middle part of the stomach
with the shape of arounded.
c. The pylorus, the lower part of the stomach
adjacent to the small intestine,
Near the pylorus there is a pyloric
sphincter which can move freely. Peristalsis is
the same as movement in the esophagus. The
stomach wall produces the hormone gastrin
and gastric juice which stimulates the stomach
wall to secrete sap stomach. Gastric juice contains hydrochloric acid (HCl), the
enzyme pepsin, lipase, and renin. Hydrochloric acid (HCl) functions to kill
germs that come along food, activates pepsinogen to pepsin, stimulates opens and
closes the pyloric sphincter, and stimulates secretion intestinal juice. Pepsin
functions to break down protein into peptones. Lipase functions to digest fat.
Renin functions to coagulate casein in milk.

Figure 11. Structure and anatomy stomatch

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