The broken-down food is then absorbed into the bloodstream from the small intestine and the nutrients are carried to each cell in the body. The digestive tract begins at the mouth and ends at the anus. It is like a long muscular tube, up to 10 metres long, with digestive organs attached along the way.
A large reservoir of microbes, such as bacteria, live within the large intestine and, to a lesser degree, in vthe rest of the digestive system. These bacteria play an important role in healthy digestion. The exact types of bacteria are particular to each person. Other factors that influence the type of bacteria in your digestive system include where you live in the world, what health conditions you have and what medications you have received. Digestion begins in the mouth. The food is ground up by the teeth and moistened with saliva to make it easy to swallow.
Saliva also has a special chemical, called an enzyme, which starts breaking down carbohydrates into sugars. Once swallowed, muscular contractions of the oesophagus massage the ball of food down into the stomach.
The food passes through a sphincter, or small muscle ring, into the stomach. Here it is mixed with gastric juices. The stomach is a muscular bag and it churns the food to help break it down mechanically as well as chemically.
The food is then squeezed through a second sphincter into the first part of the small intestine, called the duodenum.
The body can then use them to build and nourish cells and to make energy. Digestion begins in the mouth, where food and liquids are taken in. It is completed in the small intestine. The digestive tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus.
It consists of the following:. Click Image to Enlarge. Parts of other organ systems, such as nerves and blood, also play a major role in the digestive process. Muscles propel food and liquid along the digestive tract in a wave-like movement. A soft flap of tissue called the epiglottis pronounced: ep-ih-GLAH-tus closes over the windpipe when we swallow to prevent choking. From the throat, food travels down a muscular tube in the chest called the esophagus pronounced: ih-SAH-fuh-gus. Waves of muscle contractions called peristalsis pronounced: per-uh-STALL-sus force food down through the esophagus to the stomach.
A person normally isn't aware of the movements of the esophagus, stomach, and intestine that take place as food passes through the digestive tract. At the end of the esophagus, a muscular ring or valve called a sphincter pronounced: SFINK-ter allows food to enter the stomach and then squeezes shut to keep food or fluid from flowing back up into the esophagus.
The stomach muscles churn and mix the food with digestive juices that have acids and enzymes, breaking it into much smaller, digestible pieces. An acidic environment is needed for the digestion that takes place in the stomach. By the time food is ready to leave the stomach, it has been processed into a thick liquid called chyme pronounced: kime.
A walnut-sized muscular valve at the outlet of the stomach called the pylorus pronounced: pie-LOR-us keeps chyme in the stomach until it reaches the right consistency to pass into the small intestine. Chyme is then squirted down into the small intestine, where digestion of food continues so the body can absorb the nutrients into the bloodstream.
The inner wall of the small intestine is covered with millions of microscopic, finger-like projections called villi pronounced: VIH-lie. The villi are the vehicles through which nutrients can be absorbed into the blood. The blood then brings these nutrients to the rest of the body. Each part of your digestive system helps to move food and liquid through your GI tract, break food and liquid into smaller parts, or both.
Once foods are broken into small enough parts, your body can absorb and move the nutrients to where they are needed. Your large intestine absorbs water, and the waste products of digestion become stool. Nerves and hormones help control the digestive process. Food moves through your GI tract by a process called peristalsis.
The large, hollow organs of your GI tract contain a layer of muscle that enables their walls to move. The movement pushes food and liquid through your GI tract and mixes the contents within each organ.
The muscle behind the food contracts and squeezes the food forward, while the muscle in front of the food relaxes to allow the food to move. Food starts to move through your GI tract when you eat. When you swallow, your tongue pushes the food into your throat. A small flap of tissue, called the epiglottis, folds over your windpipe to prevent choking and the food passes into your esophagus.
Once you begin swallowing, the process becomes automatic. Your brain signals the muscles of the esophagus and peristalsis begins. Lower esophageal sphincter. When food reaches the end of your esophagus, a ringlike muscle—called the lower esophageal sphincter —relaxes and lets food pass into your stomach.
After food enters your stomach, the stomach muscles mix the food and liquid with digestive juices. The stomach slowly empties its contents, called chyme , into your small intestine.
Small intestine. The muscles of the small intestine mix food with digestive juices from the pancreas, liver, and intestine, and push the mixture forward for further digestion. The walls of the small intestine absorb water and the digested nutrients into your bloodstream. As peristalsis continues, the waste products of the digestive process move into the large intestine.
Large intestine. Waste products from the digestive process include undigested parts of food, fluid, and older cells from the lining of your GI tract. The large intestine absorbs water and changes the waste from liquid into stool. Peristalsis helps move the stool into your rectum.
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