The stomach is a J-shaped muscular organ that is part of the digestive system. It acts as a bag to collect and store food, and uses digestive juices to break down food into smaller molecules that can be absorbed by the body. Food mixes with stomach acids and other juices to form chyme, which then exits the stomach through sphincter valves and enters the small intestine in small amounts to neutralize acid and accommodate the intestine's narrower size.

1. The stomach, a J- shaped muscular Internal organ or visera. it is part of the
digestive or gastrointestinal system .The stomach act as a bag for collection of
food and is responsible for breaking down of food before nutrients molecules
are absorbed into the body with the aid of digestive juices.

2. 1. The fundus or upper region
2. The body or main portion
3. The antrum or lower region

3. There is need to know how food is broken down in the stomach before nutrient molecules are
absorbed by the body with the aid of digestive juices.
 The fold in the lining of the stomach are called rugae, when the stomach is filled with food the
rugae stretch out and disappear
 The food mixes with hydrochloric acid (HCl) is secreted in the lining of the stomach and other
gastric juices to form a liquid mixture called chyme, which then passes through the remaining
portion of the digestive system.
 Entry into and exit from the stomach is controlled muscular valves called sphincters. These
valves ensure open and close to ensure that food can only move forward down the gut tube
 The cardiac sphincter(named for it proximity to the heart) is located between the esophagus
and the fundus ; also called the lower esophageal sphincter(LES), it keeps food from flowing
backward into the esophagus.
 The antrum diminishes off into the poly sphincter, which regulate the passage of food into the
small intestine. Only a small amount of chyme enters the intestine with each opening of the
sphincter for two important reasons.
1. First, the intestine is much narrower than the stomach and cannot hold as much as the stomach
can.
2. Second, the chyme is highly acidic and must be thoroughly neutralized as it leaves the
stomach.