Egyptian language school (Science – grade 4 – 2nd tem)
“Summary of lesson One”
The digestive system:
- The digestive system changes the large pieces of food into small pieces soluble in water.
- The digested food is carried by the blood to all body cells.
What do we mean by?
Digestion:it is the change of food from its complex form into a simple form to let the body benefit from it.
The digestive system consists of two main parts:
1-Digestive canal :.
It consists of :
- Mouth. 2. Pharynx. 3. Esophagus. 4. Stomach. 5. Small intestine.
6. Large intestine. 7. Rectum. 8. Anus.
2- Digestive canal supplementaries:
It consists of:
1-Salivary glands. 2- Liver 3- Pancreas.
First: the digestive canal:
- Mouth:it is a cavity contains:
- Teeth. b. Tongue c. Salivary glands which open in it.
Teeth:the adult has (32 teeth) 16 in each jaw .
The number of teeth in the childhood stage is (20 teeth) 10 in each jaw.
- Tongue:
Mixes the food with saliva and helps to swallow and taste the food.
- salivary glands:
they are 3 pairs which secrete saliva in the mouth that changes starch into sugar.
- The pharynx:
-It is a common cavity between trachea and esophagus.
- Esophagus:
-It is a muscular tube allows food to pass from pharynx to the stomach.
- Stomach:
- It is a muscular sac that secretes gastric juice which changes proteins into semi liquid substance.
- it secretes gastric juice which changes protein into semi- liquid substance.
5.Small intestine:
- It is along tube of 7 meters length.
- it consists of two parts which are:
a. Duodenum. b. ileum.
- It starts with duodenum at which both bile juice and pancreatic juice are poured where:
- Bile juice secreted by liver.
- Pancreatic juice secreted by pancreas.
- Duodenum leads to ileum where intestinal juice is poured and complete digestion of food takes place.
The function of the bile juice
-Bile juice helps in digestion of fats , where it changes it to emulsified fats (fatty emulsion).
Absorption process
-The digested food is absorbed from the wall of the small intestine to the blood to be carried to all the parts of the body.
Function of small intestine
- Completes the digestion of all types of food.
- Absorption of digested food.
6- Large intestine:
-It starts with the end of small intestine then rectum and ends with anus.
Function of large intestine
- It absorbs water from the undigested food ( food remains).
- Gets rid of the undigested food (wastes) through anus out of the body.
How do you keep your digestive system healthy?
- Chewing the food very well.
- Don’t eat a lot of food rich in fats such as junk food.
- Avoid eating foods that contains additives of taste, colour and flavor.
- Avoid buying food from traders. (G.R)
To avoid gastric diseases.
Give Reason
- The importance of water for the digestion.
Because,it helps to break down the complex food substances to simple substances to be useful for the body.
- The importance of food.
Because,1 . Carbohydrates and fats provide the body with energy.
2 . Proteins help the body to grow.
3 . vitamins protect the body from diseases.
- The small intestine is very important.
Because,it completes the digestion of all types of food and absorbs digested food.