Bile is stored between meals in the gallbladder. At mealtime, it is squeezed out of the gallbladder, through the bile ducts, and into the intestine to mix with the fat in food. The bile acids dissolve fat into the watery contents of the intestine, much like detergents that dissolve grease from a frying pan.
After fat is dissolved, it is digested by enzymes from the pancreas and the lining of the intestine. Most digested molecules of food, as well as water and minerals, are absorbed through the small intestine.
The mucosa of the small intestine contains many folds that are covered with tiny fingerlike projections called villi. In turn, the villi are covered with microscopic projections called microvilli. These structures create a vast surface area through which nutrients can be absorbed. Specialized cells allow absorbed materials to cross the mucosa into the blood, where they are carried off in the bloodstream to other parts of the body for storage or further chemical change.
This part of the process varies with different types of nutrients. The Dietary Guidelines for Americans recommend that 45 to 65 percent of total daily calories be from carbohydrates. Foods rich in carbohydrates include bread, potatoes, dried peas and beans, rice, pasta, fruits, and vegetables. Many of these foods contain both starch and fiber. The digestible carbohydrates - starch and sugar - are broken into simpler molecules by enzymes in the saliva, in juice produced by the pancreas, and in the lining of the small intestine.
Fiber is undigestible and moves through the digestive tract without being broken down by enzymes. Many foods contain both soluble and insoluble fiber. Soluble fiber dissolves easily in water and takes on a soft, gel-like texture in the intestines. Insoluble fiber, on the other hand, passes essentially unchanged through the intestines.
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.
Then in the small intestine, several enzymes from the pancreatic juice and the lining of the intestine complete the breakdown of huge protein molecules into small molecules called amino acids. These small molecules can be absorbed through 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 intestine. The bile acids produced by the liver dissolve fat into tiny droplets and allow pancreatic and intestinal enzymes to break the large fat molecules into smaller ones.
Some of these small molecules are fatty acids and cholesterol. The bile acids combine with the fatty acids and cholesterol and help these molecules move into the cells of the mucosa. In these cells the small molecules are formed back into large ones, 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 food that is absorbed through the small intestine are vitamins. The two 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. Fat-soluble vitamins are stored in the liver and fatty tissue of the body, whereas water-soluble vitamins are not easily stored and excess amounts are flushed out in the urine.
Water and salt. Most of the material absorbed through the small intestine is water in which salt is dissolved. The salt and water come from the food and liquid you swallow and the juices secreted by the many digestive glands.
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. Both of these hormones work on the brain to help regulate the intake of food for energy. Together, nerves, hormones, the blood, and the organs of the digestive system conduct the complex tasks of digesting and absorbing nutrients from the foods and liquids you consume each day.
Search temple health. Your Digestive System. 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.
IFFGD is a nonprofit education and research organization. Our mission is to inform, assist, and support people affected by gastrointestinal disorders. Our original content is authored specifically for IFFGD readers, in response to your questions and concerns. If you found this article helpful, please consider supporting IFFGD with a small tax-deductible donation.
This information is in no way intended to replace the guidance of your doctor. All Rights Reserved. International Foundation for Gastrointestinal Disorders. GI Disorders. Upper GI Disorders. Lower GI Disorders. Bowel incontinence Chronic constipation Chronic diarrhea Dyssynergic defecation. Other GI Disorders. Abdominal adhesions Acute Hepatic Porphyria Anal fistulas Celiac disease Clostridium difficile Congenital sucrase-isomaltase deficiency.
Malabsorption Opioid Induced Constipation Radiation therapy injury Scleroderma Short bowel syndrome Superior mesenteric artery syndrome. Vovulus Rare diseases. Motility Disorders. Functional GI Disorders. The Digestive System. Reality Report from Miranda A. Why is digestion important When we eat such things as bread, meat, and vegetables, they are not in a form that the body can use as nourishment.
How is food digested Digestion involves the mixing of food, its movement through the digestive tract, and the chemical breakdown of the large molecules of food into smaller molecules. The third task of the stomach is to empty its contents slowly into the small intestine. The small intestine has 3 segments: the duodenum, the jejunum, and the ileum. Each part or section performs an important role in nutrient absorption.
Production of Digestive Juices The glands that act first are in the mouth — the salivary glands. Absorption and Transport of Nutrients Digested molecules of food, as well as water and minerals from the diet, are absorbed from the cavity of the upper small intestine.
Carbohydrates It is recommended that about 55 to 60 percent of total daily calories be from carbohydrates. Protein 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.
Fats Fat molecules are a rich source of energy for the body. Vitamins Another vital part of our food that is absorbed from the small intestine is the class of chemicals we call vitamins. How is the digestive process controlled?
Hormone Regulators A fascinating feature of the digestive system is that it contains its own regulators. The hormones that control digestion are gastrin, secretin, and cholecystokinin CCK : Gastrin causes the stomach to produce an acid for dissolving and digesting some foods.
It is also necessary for the normal growth of the lining of the stomach, small intestine, and colon. The gut and the brain are closely linked and can affect one another. Persevering with a balanced healthy diet during stressful times might help alleviate some of the symptoms of stress.
It is worth exploring ways to manage stress and there are a number of approaches and techniques described online and in books. A starting point could be the NHS Choices website, which has a section on recognising and managing stress. Poor hygiene can certainly increase your chance of getting food poisoning. Food poisoning is usually a short-lived illness but it can be very unpleasant while it lasts.
Always wash your hands after visiting the toilet and before handling food. Care should be taken with storage of food, particularly in hot weather. Certain foods, especially raw meat, must be kept covered, separated from other foods and well refrigerated.
While some of these are used to specify when the food will be at its best, it can be risky to eat meat after the stated date. When re-heating food, make sure it is hot all the way through e.
This is particularly important when using a microwave oven or a barbecue. All of us have short-lived gut problems from time to time. For the most part this settles down by itself and should give no cause for concern. However you should see your GP about:.
All these are especially true if you have a family history of significant gut illness. You should also see your GP if you have been taking a remedy obtain from a pharmacy for more than 2 weeks without experiencing any improvement to your symptoms. We fund life-saving research into diseases of the gut, liver and pancreas.
Champion our cause; help us fight digestive diseases and change the lives of millions of people in the UK by supporting our work today.
Skip to content Search Menu Donate. Healthy Eating and the Digestive System Download printable version. Overview 2. Digestive System 3. Healthy Eating 4. Food Hygiene 5. This information leaflet is about healthy eating To maintain good health, including a healthy digestive system, it is important to follow a balanced healthy diet that includes a range of foods.
Digestive System. The digestive system The Digestive System runs from the mouth to the anus and includes the stomach, the large and small intestines and a number of accessory organs, including the salivary glands, liver, gallbladder and pancreas. There are many different processes which contribute to a functioning and effective digestive system: Ingestion putting food in your mouth Mechanical digestion chewing and food being churned inside the digestive tract Chemical digestion digestive enzymes and substances breaking food down Absorption molecules passing from digestive system into the body Making and passing stools faeces Key components of the digestive system Mouth: the beginning of the digestive tract.
The components of the digestive system. Healthy Eating. Why is healthy eating important? What is a healthy diet? These include: Maintaining a fluid intake at around two litres per day. Monitoring portion sizes. It can be easy to get in the habit of large portion sizes. A rule of thumb for a meal is a fist-sized portion of carbohydrate and palm-sized portion of protein. Minimising fizzy or sugary drinks, including fruit juice.
Choose dilutable sugar-free squash, tea, coffee or water. Limiting alcohol intake to 14 weekly units for men and women. Avoiding or reducing intake of certain foods such as sweets, cakes, crisps, chocolate, processed meats. Eating at least two portions of fish per week, one of which should be oily eg mackerel, trout, sardines, kippers or fresh tuna.
Replacing saturated fat with polyunsaturated or mono-unsaturated fat. Can a vegetarian diet be healthy? Do I need to take vitamins or supplements? Food monitoring — how and why? Can stress affect my diet? Food Hygiene.
0コメント