Isaac Han (8) Koh Huai Ze (10) Liu Shuyang (14) Ng Wei Kai (16)
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Transcript of Isaac Han (8) Koh Huai Ze (10) Liu Shuyang (14) Ng Wei Kai (16)
Isaac Han (8)Koh Huai Ze (10)Liu Shuyang (14)
Ng Wei Kai (16)
The Digestive System
The breakdown of food into smaller pieces to allow easy absorption into the blood stream Lipids are broken down into fatty acids Proteins are broken down into individual amino acids Carbohydrates are broken down into simple sugars
Digestion – A brief introduction
Foods that we eat must be broken down into smaller pieces before they can be absorbed into the blood and carried to cells throughout the body.
Our body requires these foods to build and nourish cells and to provide energy through respiration.
Digestion – Why it is Important?
The digestive system consists of: The digestive tract
A series of hollow organs joined in a long, twisting tube from the mouth to the anus
Other organs that help the body break down and absorb food
Liver Pancreas
The Digestive System
The Digestive TractConsists of: Mouth Esophagus Stomach Small Intestine Large Intestine (Colon) Rectum Anus
Holloworgans
These hollow organs contain a lining called the mucosa
In the mouth, stomach and small intestine, the mucosa contains tiny glands that produce digestive juices to help digest food
The digestive tract also contains a layer of smooth muscle that helps break down food and move it along the tract
The Digestive Tract
Liver, pancreas and gallbladder
“solid” digestive organs
The liver and pancreas produce digestive juices that reach the intestine through small tubes called ducts
The gallbladder stores the liver’s digestive juices until they are needed in the intestine
Other organs
Digestion involves making food with digestive juices, moving it through the digestive tract, and breaking it down into smaller molecules
It begins in the mouth, and is completed in the small intestine
How is food digested?
Beginning of the digestive system
Chews up food into smaller pieces to aid digestion
Lined with a mucous membrane
Produces saliva which breaks down some starch and fats in the food
Mouth
Esophagus Swallowed food is pushed into
the esophagus Connects the mouth with the
stomach belowLower esophageal sphincter Ring-like muscle Located at the junction of the
esophagus and stomach In charge of closing the
passage between the two organs
As food approaches it, it relaxes and allows the food to pass through to the stomach
Esophagus
Functions:1. Stores the swallowed
food and liquid – muscle of the upper part of the stomach relaxes to accept large volumes of swallowed material
2. Through a churning action, mixes the food and liquid with digestive juices produced by the stomach to digest them
3. Empty its contents slowly into the small intestine
Carbohydrates spend the least amount of time in the stomach, while proteins stay in the stomach longer, and fats the longest.
Stomach
Much of the digestion and absorption of food takes place here
Primary function: to absorb nutrients and minerals found in food
The mucosa of the small intestine contains many folds called villi
The villi are covered with microscopic projections called microvilli
The structures create a vast surface area for nutrients to be absorbed
Small Intestine
Absorbs water from the remaining indigestible food matter
Connects the small intestine to the rectum
Pass useless waste material from the body
About 1.5m long
Large Intestine
Receives waste matter from the large intestine
When gas or stool comes into the rectum, sensors will send a message to the brain
Act as a temporary storage site for waste matter before it is excreted from the body through the anus
Made up of muscular walls that are able to expand to hold waste material
Rectum
Disposes waste products out of the body
Anus
Produces a digestive juice that contains a wide array of enzymes* to break down the carbohydrate, protein and fat in food
Stores bile from the liver
*enzymes: substances that speed up chemical reactions in the body
Pancreas
Produces a digestive juice called bile
Bile is stored between meals in the gallbladder
At mealtime, it is squeezed out of the gallbladder into the intestine to mix with the fat in food to dissolve the fats and digest the dissolved fats.
Liver