Physical and Chemical Digestion

Physical Digestion:
 -Is the breakdown of food by physical means.
 -Physical digestion starts when we use our knife and fork to brake down large substances.
 -Our teeth take over to grind food into small particles wich can be swallowed
 -Physical digestion also includes peristalsis which helps move food down the digestive tract and the muscular churning of food within the stomach which helps mix food substances with digestive juices and acid.


Chemical Digestion:
*   Why is chemical digestion needed?
- Chewing, churning, and mixing of food with digestive juices can only separate molecules from each other. These actions cannot split up molecules. Many nutrient molecules are too large to pass through cell membranes (i.e. they cannot be absorbed).- Molecules of water, vitamins, and minerals are small enough to be absorbed through the intestinal wall and into the blood stream.
- Proteins, carbohydrates, and fat molecules are too large and must be broken down further by chemical means. This is chemical digestion.

HOPE IT HELPS YOU!!!

Paulina Hernandez