The parts of the stomach
The stomach is part of the digestive system. It lies just under the diaphragm (the sheet of muscle just under your lungs). The top of the stomach is connected to the oesophagus (foodpipe). The other end of the stomach is connected to the first part of the small bowel, the duodenum.
The stomach has three main parts. The top is called the fundus. The middle is called the body of the stomach. The bottom is called the antrum or pylorus. There is a valve called a sphincter at each end of the stomach. The valve between the oesophagus and the top of the stomach is called the cardiac sphincter. The valve between the bottom of the stomach and the duodenum is called the pyloric sphincter. The stomach does several different jobs.
How the stomach mixes and breaks down food
The stomach is a muscular bag. Its main job is to mix up the food that is eaten and start breaking it down so that it can be easily digested. When food enters the stomach, the muscles of the stomach wall begin powerful contractions, which pass over the stomach in waves. These muscle contractions mix up the food and break it down until it is a thick liquid. This makes digestion in the duodenum easier.
Beginning the digestion of proteins
The lining of the stomach contains glands, which make and release (secrete) the stomach juices. The stomach juices contain an acid and a digestive enzyme called pepsin. These begin to flow as soon as we see or smell food, well before food even enters the stomach. The enzyme starts to break down (digest) proteins in the food so that the body can absorb them. The acid is needed for the enzyme to work properly. It also helps to kill bacteria that might be in the food and so helps to protect against food poisoning.
There are other glands in the stomach lining that make thick mucus. This mucus helps to protect the stomach lining from being damaged by the acid and protein digesting enzyme in the stomach juices....
Stomach Cancer Essay
Stomach Cancer also called gastric cancer refers to the growth of a cancerous tumor in the stomach. It can develop in any part of the stomach and grow along the stomach wall into the esophagus or small intestine. Stomach cancer is the second most common form of cancer
It also may extend through the stomach wall and spread to nearby lymph nodes and to organs such as the liver, pancreas and colon. Stomach cancer also may spread to distant organs, such as the lungs, the lymphnodes above the collar bone, and the ovaries. When stomach cancer spreads to an ovary, the tumor in the ovary is called a Krukenberg tumor.
Each year, about 24,000 people in the United States are diagnosed as suffering from stomach cancer.
The disease affects men twice as often as women, and is more common in Afro-American people than in Caucasian people. Stomach cancer is more common in Japan, Korea, parts of Eastern Europe, and Latin America than in the United States. People in these areas eat many foods that are preserved by drying, smoking, salting, or pickling. Scientists believe that eating foods preserved in these ways may play a role in the development of stomach cancer. On the other hand, fresh foods (especially fresh fruits and vegetables and properly frozen or refrigerated fresh foods) may protect against this disease.
Some studies suggest that a type of bacteria called Helicobacter pilori, which may cause stomach inflammation and ulcers, may be an important risk factor for this disease.
The overall five-year survival rate for people with stomach cancer in the United States is 22%. One reason for this is that most stomach cancers are found at an advanced stage. The outlook for survival is worse, if the cancer is in the upper part of the stomach.
In its early stage, stomach cancer has no specific...
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