Why do we need a digestive system ?
- Each cell in our body needs food to carry out its functions.
- The food required by every cell in our body is delivered by the blood system.
- The food is in very large particles .
- These large particles need to be broken down to smaller particles before they can fit in the blood or travel through the cell membrane.
The organs of the digestive system and their functions.
- Mouth - take in food ,crush food with the teeth Amylase is added to the food.
- Oesophagus - carry down food to the stomach.
- Stomach - churn the food . Add acid to the food.
- Small intestine - further digestion by enzymes absorption of digested food into the blood.
- Large intestine/Colon - water is absorbed into the blood. The waste is prepared for egestion.
- Salivary glands - make saliva ,which contains an enzyme ,amylase ,to break starch down to smaller sugars.
- Liver - produces liquid bile, which helps digest fats. Regulates the amount of each food in the blood.
- Gall bladder- stores bile from the liver until it is needed.
- Pancreas - makes enzymes to break down food.
The acid that is produced in the stomach is called hydrochloric acid.
The teeth and their functions.
- Incisors - cut and slice food.
- Canines - Grip and tear food
- Premolars - chew and grind food.
- Molars - chew and grind food.
What is an enzyme?
An enzyme is a chemical , found in living organisms , that speeds up chemical reactions.
One of the enzymes in the digestive system is amylase. Amylase breaks down large starch molecules inot smaller molecules of a sugar called maltose.
A second enzyme called maltase breaks down the maltose into glucose. Glucose molecules are small enough to be absorbed inot the blood and eventually inot the cells.
Peristalsis is a muscular movement that only occurs in the muscles of the digestive system. It is used to push the food along the system.
A system is a group of organs working together.