Digestive System

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Digestive System:

Digestive System By : $akshi $ood Class : 10 th Roll no : 04

What is Digestive System:

What is Digestive System The system by which ingested food is acted upon by physical and chemical means to provide the body absorbable nutrients and to excrete waste products; in mammals the system includes the alimentary canal extending from mouth to anus and the hormones and enzymes assisting in digestion.

Four stages of food processing:

Four stages of food processing Ingestion : the act of eating/drinking . Digestion : the process of breaking food down into smaller molecules. Absorption :. cells absorb the small molecules of nutrients. Elimination : undigested material passes out of the body.

The Alimentary Canal:

The Alimentary Canal The human digestive system consists primarily of a tube called the alimentary canal. Each section of canal is specialized for a particular function of digestion. The alimentary canal is of 9m.

Major parts of alimentary canal:

Major parts of alimentary canal Mouth Pharynx Esophagus Stomach Small Intestine Large Intestine Rectum

Accessory Organs of Digestive System:

Accessory Organs of Digestive System Liver Pancreas Gall Bladder

Journey through the digestive system:

Journey through the digestive system Mouth The digestion begins through two methods: 1) Mechanical digestion-teeth and tongue cut, mash and grind food into smaller pieces. 2) Chemical digestion-salivary amylase breaks carbohydrates into sugar. Food is then pushed to pharynx.

Journey through the digestive system:

Journey through the digestive system Pharynx In the back of the mouth of the throat, food is shaped into ball of food called bolus. The bolus is then pushed into esophagus .

Journey through the digestive system:

Journey through the digestive system Esophagus It is a muscular, flexible tube about of foot long in which food enters from pharynx and then pushed into stomach.

Journey through the digestive system:

Journey through the digestive system Stomach An elastic, muscular sac where majority of digestion occurs. It hold about 2 cups when empty but can expand to more than 4 times that size, holding a complete meal and beverage. Gastric juice is secreted by stomach glands- is extremely acidic Mucus is also secreted Chyme is the mixture of gastric juice and food

Journey through the digestive system:

Journey through the digestive system Stomach ( cont. )  The esophageal sphincter at the top and pyloric sphincter at the bottom seal off the stomach while it churns. Fold in the stomach are called rugae. Food stays in the stomach for 2-5 hours. Food is then pushed into small intestine.

Journey through the digestive system:

Journey through the digestive system Small Intestine A long, narrow tube where most nutrients are absorbed About 20-25 feet long Divided into 3 parts: 1) Duodenum 2)Jejunum 3) Ileum

Journey through the digestive system:

Journey through the digestive system Liver The body’s largest organ Produces bile, which is stored in the gall bladder until needed and then secreted into the duodenum The liver is also the first stop for nutrients after they are absorbed by the small intestine; it filters out harmful substances before passing out some nutrients along to the rest of body and placing other nutrients in storage for later use.

Journey through the digestive system:

Journey through the digestive system Pancreas Produces pancreatic juice which includes insulin. Pancreatic juice is also secreted into the duodenum.

Journey through the digestive system:

Journey through the digestive system Small intestine It has huge surface area designed to maximize absorption of nutrients. Its interior wall is folded into small finger like projections called villi Food is then pushed into large intestine .

Journey through the digestive system:

Journey through the digestive system Large Intestine Also known as the colon Is wider and shorter than small intestine Main function is to absorb water

Journey through the digestive system:

Journey through the digestive system Appendix A vestigial organ near the junction of small and large intestines. Rectum Stores solid waste until elimination occurs Anus The exit from the digestive system

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