Gastrointestinal tract

What is Small Intestine?

Picture of the Intestines
Diverticulosis occurs when pouches form on the intestinal wall. Journal of Lipid Research. It carries swallowed masses of chewed food along its length. In the large intestine , or colon, the gas volume is usually to cubic cm 6 to 12 cubic inches. J Natl Cancer Inst. Macrophages can be readily labelled experimentally through their phagocytosis of injected carbon particles. The cytoplasm is strongly acidophilic , is somewhat grainy in appearance, and is typically less-intensely stained in a "halo" zone midway between the nucleus and the cell membrane.

Digestive System Anatomy

Intestinal gas

A number of conditions can cause a failure in the process of absorption. These include illness, medication, trauma and genetically-linked conditions.

If you fail to absorb the nutrients in the food you eat, health issues arise. Some forms of malabsorption apply to most nutrients while others affect a particular one.

The most common form of malabsorption, celiac disease, occurs in people who cannot digest gluten, a protein found in wheat, barley and rye grains. However, malabsorption can occur as a result of obstruction or disease of the gall bladder, liver failure, pancreatic disease, abnormal bowel mobility, overgrowth of bacteria and many other maladies and anomalies.

The number one symptom of the malabsorption of protein is edema. Your ankles, feet and hands get noticeably swollen. Your shoes and rings feel tighter and your joints feel stiff. If you press a finger into the lower part of your shin, you leave an imprint in the skin that takes many minutes to return to its normal shape.

This demonstrates pitting edema. Malabsorption will cause you to lose weight, give you chronic diarrhea and abdominal distention. A child with celiac disease experiences a delay in growth. A variant of celiac symptoms can appear as a skin rash that has pustules and feels very itchy. Not all people with celiac disease experience a rash. In the case of protein malabsorption, a gluten-free diet needs to be followed.

You can probably get the protein you need from meat, poultry, fish, eggs and dairy. Carrying excess fluid around can place undue pressure on your heart and lungs. Diarrhea and weight loss will make you feel sluggish and weak. It connects the throat above with the stomach below. At the junction of the esophagus and stomach, there is a ringlike valve closing the passage between the two organs. However, as the food approaches the closed ring, the surrounding muscles relax and allow the food to pass.

The food then enters the stomach, which has three mechanical tasks to do. First, the stomach must store the swallowed food and liquid. This requires the muscle of the upper part of the stomach to relax and accept large volumes of swallowed material. The second job is to mix up the food, liquid, and digestive juice produced by the stomach. The lower part of the stomach mixes these materials by its muscle action. The third task of the stomach is to empty its contents slowly into the small intestine.

Several factors affect emptying of the stomach, including the nature of the food mainly its fat and protein content and the degree of muscle action of the emptying stomach and the next organ to receive the stomach contents the small intestine. As the food is digested in the small intestine and dissolved into the juices from the pancreas, liver, and intestine, the contents of the intestine are mixed and pushed forward to allow further digestion.

Glands of the digestive system are crucial to the process of digestion. They produce both the juices that break down the food and the hormones that help to control the process. The glands that act first are in the mouth--the salivary glands. Saliva produced by these glands contains an enzyme that begins to digest the starch from food into smaller molecules. The next set of digestive glands is in the stomach lining.

They produce stomach acid and an enzyme that digests protein. One of the unsolved puzzles of the digestive system is why the acid juice of the stomach does not dissolve the tissue of the stomach itself.

In most people, the stomach mucosa is able to resist the juice, although food and other tissues of the body cannot. After the stomach empties the food and its juice into the small intestine, the juices of two other digestive organs mix with the food to continue the process of digestion. One of these organs is the pancreas. It produces a juice that contains a wide array of enzymes to break down the carbohydrates, fat, and protein in our food.

Other enzymes that are active in the process come from glands in the wall of the intestine or even a part of that wall. The liver produces yet another digestive juice--bile. The bile is stored between meals in the gallbladder. At mealtime, it is squeezed out of the gallbladder into the bile ducts to reach the intestine and mix with the fat in our food. The bile acids dissolve the fat into the watery contents of the intestine, much like detergents that dissolve grease from a frying pan.

After the fat is dissolved, it is digested by enzymes from the pancreas and the lining of the intestine. How Is the Digestive Process Controlled?

A fascinating feature of the digestive system is that it contains its own regulators. The major hormones that control the functions of the digestive system are produced and released by cells in the mucosa of the stomach and small intestine. These hormones are released into the blood of the digestive tract, travel back to the heart and through the arteries, and return to the digestive system, where they stimulate digestive juices and cause organ movement.

The hormones that control digestion are gastrin, secretin, and cholecystokinin CCK: It is also necessary for the normal growth of the lining of the stomach, small intestine, and colon. It stimulates the stomach to produce pepsin, an enzyme that digests protein, and it also stimulates the liver to produce bile.

Two types of nerves help to control the action of the digestive system. Extrinsic outside nerves come to the digestive organs from the unconscious part of the brain or from the spinal cord. They release a chemical called acetylcholine and another called adrenaline. Acetylcholine causes the muscle of the digestive organs to squeeze with more force and increase the "push" of food and juice through the digestive tract.

Acetylcholine also causes the stomach and pancreas to produce more digestive juice. Adrenaline relaxes the muscle of the stomach and intestine and decreases the flow of blood to these organs.

Even more important, though, are the intrinsic inside nerves, which make up a very dense network embedded in the walls of the esophagus, stomach, small intestine, and colon. The intrinsic nerves are triggered to act when the walls of the hollow organs are stretched by food. They release many different substances that speed up or delay the movement of food and the production of juices by the digestive organs. Food and Nutrient Digestion - Overview.

Diet and Nutrition Info. Calories Burned by Exercise. Health Benefits of Activity. Low Calorie Cooking Ideas. Absorption and Transport of Nutrients Digested molecules of food, water and minerals from the diet, are absorbed from the cavity of the upper small intestine.

Hours The large, hollow organs of the digestive system contain muscle that enables their walls to move.

Conditions Topics