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digestive system Flashcards

Nothing ‘sits’ in your gut. Your digestive system is not a recycling centre that carefully separates your food into meat, vegetables, grains and so on and then processes them separately. You chew incoming food into a rough mash; it moves into the stomach for another round of mixing, mashing and marinating, and then travels through the intestine as a fairly homogenous paste. Nearly 7 meters in length, the small intestine is folded and curled around a small area in the abdominal cavity.

The pancreas is near the liver, and is the main source of enzymes for digesting fats (lipids) and proteins – the intestinal walls have enzymes that will digest polysaccharides. Pancreatic secretions from ductal cells contain bicarbonate ions and are alkaline in order to neutralize the acidic chyme that the stomach churns out. Control of the exocrine function of the pancreas are via the hormone gastrin, cholecystokinin and secretin, which are hormones secreted by cells in the stomach and duodenum, in response to distension and/or food and which causes secretion of pancreatic juices.

Hemorrhoids are the most common cause of bleeding in the digestive tract. Hemorrhoids are enlarged veins in the anal area which produces bright red blood that you see in the toilet or on the toilet paper. Researchers have not found out what exactly causes IBS. One idea is that people with IBS have a large intestine (colon) that is sensitive to certain foods and stress. The immune system may also be involved.

Stroma cells are strung along the GI tract and are part of the system that helps the body to know when to move food through the digestive system. The large intestine is divided into the cecum, colon, rectum, and anal canal. In its course, describes an arch which surrounds the convolutions of the small intestine.

And, hepatocytes store fat-soluble vitamins and excess substances such as glucose (sugar) for release when the body requires extra energy. The six major activities of the digestive system are ingestion, propulsion, mechanical breakdown, chemical digestion, absorption, and elimination. First, food is ingested, chewed, and swallowed. Next, muscular contractions propel it through the alimentary canal and physically break it down into tiny particles. Digestive fluids chemically break down the nutrients from food into molecules small enough for absorption.

The final step in digestion is the elimination of undigested food content and waste products. After food passes through the small intestine, the undigested food material enters the colon, where most of the water is reabsorbed.

Teeth chop food into small pieces, which are moistened by saliva before the tongue and other muscles push the food into the pharynx. Most of the nutrients are absorbed from the small intestine and moved into the blood stream via a system of small folds, called vili.

The amino acids are absorbed into the bloodstream through the small intestines. The steps in protein digestion are summarized in Figure 2 and Table 2. The digestion of carbohydrates begins in the mouth. The salivary enzyme amylase begins the breakdown of food starches into maltose, a disaccharide.

It has been estimated that there are over 500 species of bacteria present in the large intestine, and these friendly (commensal) bacteria perform a variety of functions. For example, undigested carbohydrates (fibre) are metabolised to short-chain fatty acids, and small amounts of vitamins, especially vitamin K and the vitamin B group, are produced for absorption into the blood. On reaching the end of the small intestine, all the digested food products, along with the minerals and vitamins that are useful to the body, should have been removed from the watery contents. What remains consists of the indigestible components of food such as cellulose from the consumption of plant-based foods.

The partially digested food enters the duodenum as a thick semi-liquid chyme. In the small intestine, the larger part of digestion takes place and this is helped by the secretions of bile, pancreatic juice and intestinal juice. An earthworm’s digestive system consists of a mouth, pharynx, esophagus, crop, gizzard, and intestine. The mouth is surrounded by strong lips, which act like a hand to grab pieces of dead grass, leaves, and weeds, with bits of soil to help chew.

These muscles allow the stomach to squeeze and churn the food during mechanical digestion. Also known as the gastrointestinal (GI) tract, the digestive system begins at the mouth, includes the esophagus, stomach, small intestine, large intestine (also known as the colon) and rectum, and ends at the anus. The entire system – from mouth to anus – is about 30 feet (9 meters) long, according to the American Society of Gastrointestinal Endoscopy (ASGE).

the body's process of eliminating indigestible

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