The Digestive System

The lining of the stomach walls has ridges called rugae, which allow the stomach to expand and also help channel liquid internally. The lower oesophageal sphincter is a ring of smooth muscle that controls the entry of food from the oesophagus into the stomach. Once food has passed into the stomach, the sphincter closes to prevent the acidic stomach contents from coming back up.

The function of gastric acid is twofold 1) it kills most of the bacteria in food, stimulates hunger, and activates pepsinogen into pepsin, and 2) denatures the complex protein molecule as a precursor to protein digestion through enzyme action in the stomach and small intestines. Near the top of the pits, closest to the contents of the stomach, there are mucous-producing cells called goblet cells that help protect the stomach from self-digestion.

Waste products of digestion, including parts of food that are still too large, become stool. Digestion is important because your body needs nutrients from food and drink to work properly and stay healthy.

Protein Functions in the Human Body and in Our Cells

Mucous neck cells-Gastric glands in the upper part of the stomach contain mucous neck cells that secrete thin, acidic mucus that is much different from the mucus secreted by the goblet cells of the surface epithelium. The role of this mucus is not currently known.

Some ulcers can bleed very slowly so the person won’t recognize the loss of blood. Over time, the iron in your body will run out, which in turn, will cause anemia.

The much larger glands of the fundus and body of the stomach, the site of most chemical digestion, produce most of the gastric secretions.

One idea is that people with IBS have a large intestine (colon) that is sensitive to certain foods and stress. The immune system may also be involved.

The duodenum receives pancreatic enzymes from the pancreas and bile from the liver and gallbladder. These fluids, which enter the duodenum through an opening called the sphincter of Oddi, are important in aiding digestion and absorption.

Cholecystokinin (CCK) has most effect on the gall bladder, but it also decreases gastric emptying. In a different and rare manner, secretin, produced in the small intestine, has most effects on the pancreas, but will also diminish acid secretion in the stomach. Erosions, ulcers, and tumors can cause bleeding. When blood is in the stomach it starts the digestive process and turns black. When this happens, the person can have black stool or vomit.

But as we know, heartburn, indigestion, and acid reflux result from too little stomach acid rather than too much. The duodenum is the first segment of the small intestine, and the stomach releases food into it. Food enters the duodenum through the pyloric sphincter in amounts that the small intestine can digest. When full, the duodenum signals the stomach to stop emptying. In hypochlorhydria and achlorhydria, there is low or no gastric acid in the stomach, potentially leading to problems as the disinfectant properties of the gastric lumen are decreased.

The acid is required to separate vitamin B12 from food. Intrinsic factor is necessary for the absorption of vitamin B12 in the small intestine. Doctors can prescribe a way to overcome these problems if no gastric juice is made. Another potential problem with achlorhydria (no stomach acid) is bacterial overgrowth in the stomach.

Other symptoms are nausea, vomiting, diarrhea, bleeding caused by continual vomiting, and dehydration caused by the nausea and diarrhea. Another more serious complication is total blockage of the bile duct which leads to jaundice, which if it is not corrected naturally or by surgical procedure can be fatal, as it causes liver damage. The only long term solution is the removal of the gallbladder. Cholestasis is the blockage in the supply of bile into the digestive tract. It can be “intrahepatic” (the obstruction is in the liver) or “extrahepatic” (outside the liver).

Digestion begins in the mouth. When you chew your food it is mixed with saliva, which not only supplies moisture but also the carbohydrate-digesting enzyme, amylase. When you eat raw food, its enzymes work with the salivary amylase to begin digestion. High levels of circulating gastrin can also occur when the pH of the stomach is high (i.e. not acidic enough), for example, in pernicious anaemia or atrophic gastritis when the stomach lining is damaged and unable to produce and release acid, and during treatment with antacid drugs.

Without activated pepsin in the stomach, protein will pass into the small intestine in an undigested form. An enzyme called trypsin is present in the small intestine after we eat and does the same job as pepsin. It works in the basic environment of the intestine, where most nutrient absorption takes place. Other intestinal enzymes complete the digestion of proteins into individual amino acids, which are then absorbed into the bloodstream. Nevertheless, without the action of pepsin, digestion may be reduced.

does stomach acid enters the small intestine

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