Download Physical and Chemical Changes of Food in the Digestive Tract

Physical and Chemical Changes of Food in
the Digestive Tract
Prepared by: Mrs. Lucia Traya
7 Grade Science
WAMS
THE DIGESTIVE SYSTEM
Mouth- Physical digestion or change of food materials:
Teeth grind food down to smaller pieces
- Chemical digestion or change of food materials:
Enzymes in saliva called amylase breaks down some of
the food like starch before it travels down the esophagus.
Stomach- Physical digestion occurs when muscles in stomach churn
food.
- Chemical digestion occurs when stomach acids, gastric
juices, and enzymes break down food and breaking its
molecular structures forming another substance.
Small Intestines- Chemical digestion occurs to food materials due to
the chemical secretion/production of pancreatic
juices, bile a chemical substance produced by the
liver, as well as other enzymes that break down
food so it can be easily absorbed by the cells.
Large Intestines- Physical digestion occurs when the walls of the large
intestines absorb the water and minerals, and feces
the waste product of digestion is temporarily stored
then pushed out of through the anus.
X the Changes
Example
Breaking food into smaller pieces by the teeth
Hydrochloric acid breaking down the food in stomach
Removal of water from food materials in the large intestines
Breaking down food into starches when mixed with saliva
Pancreatic juices neutralize acid in the small intestines
Continual mixing of food materials in the intestine
Churning and mixing of food in the stomach
Water and digestive enzymes break down fats, proteins, and
carbohydrates into smaller molecules
Physical
Chemical
Summary:
When food enters the mouth, the process of chewing
mechanically/physically breaks food down into smaller
pieces. The act of chewing releases saliva from the salivary
glands in the mouth. Saliva contains enzymes that
chemically break down starch or carbohydrates in food.
When food travels to the stomach, it mixes with acids and
other enzymes that break down food chemically. The
muscles in the stomach physically churn the food.
When food enters the small intestine it comes in contact
with enzymes from the liver and pancreas.
These enzymes from the liver and pancreas work to break
down food chemically for easier absorption of nutrients into
into the villi of the walls of the small intestines.
Food materials that cannot be digested passes through the
Large intestine. The large intestine also absorbs water and
Minerals before it compacts the waste material for excretion
or removal through the anus.