What organs are affected by diverticulitis? What are the names of the tissue layers of the stomach? What are dimensions of the small intestine? What are reasons to explain why the small intestine Where does the process of digestion begin?
Are nutrients absorbed from the large intestine? How do nutrients, absorbed by the small intestine, travel to the individual cells of the human body? Peristalsis is an involuntary muscular action that pushes food through your digestive system. It's an important part of the digestive process. If you were to watch this process on an X-ray, it would almost look like an ocean wave pushing food from one organ to the next.
In the first step of this journey, food moves down your food pipe esophagus. This takes it from your throat to your stomach. The gateway to your stomach is called the lower esophageal sphincter. This ring-like muscle opens and closes the passage between your esophagus and your stomach, as needed. During the digestive process, the sphincter relaxes and lets food pass into your stomach. Food goes through a significant part of the digestive process inside your stomach.
You may think of your stomach as a simple pouch. Bile is stored in the gallbladder until it is needed. The pancreas makes enzymes that help digest proteins, fats, and carbs. It also makes a substance that neutralizes stomach acid. These enzymes and bile travel through special pathways called ducts into the small intestine, where they help to break down food.
The liver also helps process nutrients in the bloodstream. From the small intestine, undigested food and some water travels to the large intestine through a muscular ring or valve that prevents food from returning to the small intestine.
By the time food reaches the large intestine, the work of absorbing nutrients is nearly finished. The large intestine's main job is to remove water from the undigested matter and form solid waste poop to be excreted. Reviewed by: Larissa Hirsch, MD. Larger text size Large text size Regular text size. What Is the Digestive System? Almost all animals have a tube-type digestive system in which food: enters the mouth passes through a long tube exits the body as feces poop through the anus Along the way, food is broken down into tiny molecules so that the body can absorb nutrients it needs: Protein must be broken down into amino acids.
Starches break down into simple sugars. Table sugar is another carbohydrate that must be digested to be useful. An enzyme in the lining of the small intestine digests table sugar into glucose and fructose, each of which can be absorbed from the intestinal cavity into the blood.
Milk contains yet another type of sugar, lactose, which is changed into absorbable molecules by an enzyme called lactase, also found in the intestinal lining. Foods such as meat, eggs, and beans consist of giant molecules of protein that must be digested by enzymes before they can be used to build and repair body tissues. An enzyme in the juice of the stomach starts the digestion of swallowed protein.
Further digestion of the protein is completed in the small intestine. Here, several enzymes from the pancreatic juice and the lining of the intestine carry out the breakdown of huge protein molecules into small molecules called amino acids. These small molecules can be absorbed from the hollow of the small intestine into the blood and then be carried to all parts of the body to build the walls and other parts of cells.
Fat molecules are a rich source of energy for the body. The first step in digestion of a fat such as butter is to dissolve it into the watery content of the intestinal cavity. The bile acids produced by the liver act as natural detergents to dissolve fat in water and allow the enzymes to break the large fat molecules into smaller molecules, some of which are fatty acids and cholesterol. The bile acids combine with the fatty acids and cholesterol and help these molecules to move into the cells of the mucosa.
In these cells the small molecules are formed back into large molecules, most of which pass into vessels called lymphatics near the intestine. These small vessels carry the reformed fat to the veins of the chest, and the blood carries the fat to storage depots in different parts of the body.
Another vital part of our food that is absorbed from the small intestine is the class of chemicals we call vitamins. The two different types of vitamins are classified by the fluid in which they can be dissolved: water-soluble vitamins all the B vitamins and vitamin C and fat-soluble vitamins vitamins A, D, E, and K. Water and salt. Most of the material absorbed from the cavity of the small intestine is water in which salt is dissolved.
The salt and water come from the food and liquid we swallow and the juices secreted by the many digestive glands. 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.
Two types of nerves help to control the action of the digestive system — extrinsic and intrinsic nerves. 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 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.
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