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Digestive system

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bob bobbyson

on 30 August 2013

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Transcript of Digestive system

The Digestive System!

By Rojaun Samuda
The Digestive System is one of the many organ systems in the body. Its main functions are to absorb and to digest. While the food passes through the digestive tract, nutrients are absorbed into the body. There are two types of digestion which are mechanical and chemical and they are show in the first stage of digestion which begins in the mouth.
Chemical Digestion in the Mouth
Chemical digestion in the mouth is achieved by saliva. Saliva is a liquid substance that is used to chemically break down food and to make it moist. Salivary glands around the mouth produce saliva and send it into the mouth. The saliva is able to break down food by using specialized proteins called enzymes.
The Mouth
In the mouth, there are two types of digestion occurring which are mechanical and chemical digestion. Mechanical digestion is caused by the teeth and chemical digestion is caused by saliva. Once the food is done being broken down within the mouth, the tongue pushes it towards the esophagus.
Mechanical Digestion in the Mouth
Mechanical digestion is done by the teeth. The teeth crush and crumble food to make it smaller. Each tooth is designed in a way so that it is able to break down food. Premolars are for mashing, incisors and canines are for shredding, and molars are for grinding up food.
FUN FACT: The average amount of teeth in a human adult is 32
The esophagus is a very long tube that transfers food from the mouth directly to the stomach. But, it also continues digestion. At this point, the food is called a bolus. The bolus moves to the stomach because it is being forced by involuntary muscle contractions within the esophagus continuing mechanical digestion. The bolus then enters the stomach.
Allen, Katy, Linda Berg, and Mark Taylor. Human Body Systems & Health. Austin: Holt, Rinehart, Winston, 2005. Print
Mechanical Digestion in the Stomach
Food in the stomach is broken down by involuntary muscle contractions within the stomach to break it into smaller pieces.
Chemical Digestion in the Stomach
Stomach cells secrete hydrochloric acid, pepsinogen, and other hormones that chemically digest the bolus. These chemicals make the bolus very pasty.
(Liver/Gallbladder, Pancreas)
The liver, a large reddish brown organ, produces a chemical called bile. The liver also stores nutrients and breaks down toxins. Bile is transferred from the gallbladder, a sac-shaped organ, for storage. On the way to the small intestine, the chyme is mixed with the bile, during peristalsis, to further break down the food. The pancreas, an oval organ behind the stomach, also produces digestive enzymes that intercept the chyme and break it down. These organs continue chemical digestion.
The stomach is a chamber located under the diaphragm in the upper abdominal cavity. It is divided into three regions: the fundus, body and the antrum. Once the bolus reaches the stomach, the stomach expands because of folds in the stomach wall call rugae. Like the mouth, the stomach does both mechanical and chemical digestion. After the bolus is done being digested by the stomach, it will go through the duodenum and goes into the small intestine in the form of a pulpy, acidic fluid called chyme.
FUN FACT: The largest organ in the body is the liver! WOW!
Small Intestine
In the small intestine, nutrients are absorbed from the chyme by tiny fingerlike projections called villi and are sent to the blood. The three parts of the small intestine, which are called the duodenum, jejunum, and ileum, all absorb nutrients and water more than they break down food. Therefore, the small intestine performs chemical and mechanical digestion. Chyme not absorbed enters the large intestine through the cecum.
FUN FACT: The small intestine is about 20 feet long!
Large intestine
The large intestine is about 4.9 feet long(app.5 ft) and 2.5 cm in diameter. Once the chyme enters the large intestine, water and salt are absorbed as it passes through. As more water is absorbed, the chyme is turned into a solid substance called feces, or stool. The large intestine, like the small intestine, also performs chemical and mechanical digestion.The stool is then transferred to the rectum.
Rectum and Anus
Once the feces leave the large intestine, it is stored in the rectum until it can be released. When it is ready to leave the body, it goes through a small opening called the anus. the"food" has now completed it's journey through the digestive tract.
The Digestive Tract
1. Mouth/Teeth
2. Salivary Glands
3. Pharynx
4. Esophagus
5. Stomach
6. Liver
7. Gallbladder
8. Pancreas
9. Small Intestine
10. Large Intestine
11. Rectum
12. Anus
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