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The digestive system is

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Presentation on theme: "The digestive system is"— Presentation transcript:


2 The digestive system is
made of hollow organs joined in a long, twisting tube from the mouth to the anus—and other organs that help the body break down and absorb food. Functions: Ingestion Digestion Absorption Elimination

3 or to eat The first activity of the digestive system
is to take in food through the mouth. This process, called ingestion, has to take place before anything else can happen.

4 or to break down Digestion begins in the mouth with
mechanical (physical digestion). Teeth helped by the tongue and lips (cut, tear, chop, grind and push) chew the food; at the same time salivary glands produce enzymes (chemical digestion) in saliva to help break down food and swallow. The Human mouth can make up to three pints of saliva a day.

5 The food is pushed to the pharynx (throat).
Then into the esophagus (food tube); a smooth muscle that contracts automatically to push the food into the stomach. Digestion continues with churning and mixing actions in the stomach which produces a soup like mixture called chyme. The chyme then goes into the small intesitne. The average human stomach holds about 48 ounces of food matter. Food stays in the stomach for two to three hours before it is emptied into the small intestine.

6 Absorption is when nutrients pass through the cell membrane in the
small intestine into the blood or lymph capillaries. The liver produces a substance called bile, which is stored in the gall bladder and then squeezed out into the intestine. Bile goes to work on the fat in foods, dissolving it into a liquid the body can digest. The average human small intestine is about 1.5 to 2 inches wide. If you stretched it out, it would measure about 22 feet in length.

7 or to remove The food molecules that cannot be
digested or absorbed move into the large intestine where water is absorbed. Feces (brown solid waste) is then stored in the rectum briefly. Elimination or defecation is the removal of indigestible wastes (feces) through the anus.

8 Large Intestine According to a study from the Stanford
University School of Medicine, there are more than 5,800 different species and strains of bacteria in the human colon (large intestine). Most of them are benign or even beneficial. Some of them provide nutrients like vitamin K, and others keep the bad bacteria under control.

9 A Foods Tale Digestion of food begins in the mouth, with mechanical
breakdown of ingested material by chewing with your teeth. Additionally, food in the mouth is mixed with saliva, which contains a digesting enzyme, known as amylase. This begins the chemical breakdown of food better known as chemical digestion. After chewing, food is swallowed down the pharynx (throat), and enters the esophagus.

10 A Foods Tale The esophagus is a tube to transfer ingested
material from the mouth to the stomach – very little, if any, breakdown of food occurs in the esophagus.

11 A Foods Tale Food then passes into the stomach, where it is exposed
to acid, and additional enzymes promote protein and fat breakdown.

12 A Foods Tale Next, food passes into the small intestine, where
additional enzymes from the liver and pancreas are secreted and mixed with food, to further break down protein and carbohydrates, and to emulsify fats. Additionally, food absorption occurs in the small intestine. If breakdown of ingested material and absorption do not occur normally symptoms of food intolerance result (diarrhea or constipation).

13 A Foods Tale Finally, food passes into the
large intestine, where excess water is absorbed, and water is stored in the form of feces. Food can stay in the large intestine for a long time, up to 96 hours! Very little in the way of nutrients is absorbed by the colon – if absorption hasn’t occurred in the small intestine, those leftover nutrients will be broken down by the bacteria in the colon.

14 A Foods Tale The solid parts of the food which have not
been absorbed are stored in the rectum. When the rectum is full, the remains of the food are passed out (eliminated) of the body through the anus.


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