Download The digestive system

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 :
1. Mouth. 2. Pharynx.
6. Large intestine.
3. Esophagus. 4. Stomach.
7. Rectum.
8. Anus.
5. Small intestine.
2- Digestive canal supplementaries:
It consists of:
1- Salivary glands.
2- Liver
3- Pancreas.
First: the digestive canal:
1. Mouth: it is a cavity contains:
a. 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.
2. The pharynx:
- It is a common cavity between trachea and esophagus.
3. Esophagus:
- It is a muscular tube allows food to pass from pharynx to the
stomach.
4. 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
1.
2.
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
1. It absorbs water from the undigested food ( food remains).
2. Gets rid of the undigested food (wastes) through anus out of the
body.
How do you keep your digestive system healthy?
1. Chewing the food very well.
2. Don’t eat a lot of food rich in fats such as junk food.
3. Avoid eating foods that contains additives of taste, colour and flavor.
4. Avoid buying food from traders.
To avoid gastric diseases.
(G.R)
Give Reason
1. 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.
2. 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.
3. The small intestine is very important.
Because, it completes the digestion of all types of food and absorbs
digested food.