Gastric Absorption

Gastric enzymes begin breaking down proteins, but the stomach wall is not well-adapted to absorb digestive

Oh, My Aching Stomach!

The food at the barbecue was so terrific that Perry W. didn't notice how much he was consuming —two burgers, three hot dogs, beans in a spicy sauce, loads of chips, several beers, and ice cream for dessert. Later, he paid for it, as a feeling of fullness became abdominal pain, then heartburn, as stomach contents backed up into his esophagus.

Perry found relief with an over-the-counter antacid product. Antacids raise the pH of the stomach within minutes. They usually include a compound containing either sodium, calcium, magnesium, or aluminum. Another ingredient in some products is simethicone, which breaks up gas bubbles in the digestive tract. If antacids do not help within a few minutes or they are used for longer than two weeks, a doctor should be consulted. The problem may be more serious than overeating.

Avoiding acid indigestion and heartburn is a more healthful approach than gorging and then reaching for medication—or even taking products that lower acid production before a large or spicy meal. Some tips:

• Avoid large meals. The more food, the more acid the stomach produces.

• Eat slowly so that stomach acid secretion is more gradual.

Do not lie down immediately after eating. Being upright enables gravity to help food move along the alimentary canal. If prone to indigestion or heartburn, avoid caffeine, which increases stomach acid secretion.

Cigarettes and alcohol irritate the stomach lining and relax the sphincter at the junction between the stomach and the esophagus. This makes it easier for food to return to the esophagus, causing heartburn. Do not eat acidic foods, such as citrus fruits and tomatoes, unless it is at least three hours before bedtime. Use a pillow that elevates the head six to eight inches above the stomach. ■

¡«■fll Phases of Gastric

Ml!H Secretion

Phase

Action

Cephalic phase

The sight, taste, smell, or thought of food triggers parasympathetic reflexes. Gastric juice is secreted in response.

Gastric phase

Food in stomach chemically and mechanically stimulates release of gastrin, which, in turn, stimulates secretion of gastric juice; reflex responses also stimulate gastric juice secretion.

Intestinal phase

As food enters the small intestine, it stimulates intestinal cells to release intestinal gastrin, which, in turn, promotes the secretion of gastric juice from the stomach wall.

products. The stomach absorbs only some water and certain salts, as well as certain lipid-soluble drugs. Most nutrients are absorbed in the small intestine. Alcohol, which is not a nutrient, is absorbed both in the small intestine and stomach. This is why the intoxicat ing effects of alcohol are felt soon after consuming alcoholic beverages.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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