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.

Example PhysicalChemical 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 X the Changes

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.

During which type of digestion where large molecules of carbohydrates or starch be broken down into simpler sugars? A.Mechanical digestion B.Physical digestion C.Chemical digestion D.A and B

Answer: C. Chemical digestion

Amylase is a type of enzyme present in our saliva, and it’s responsible for the chemical digestion of which type of food Molecules into simpler sugars? F. Protein G. Lipids H. Fats I. Carbohydrates

Answer: I. Carbohydrates

When the chemical composition of molecules in Food are broken down chemically, the atoms of various compounds from food rearrange to form another substances, and releasing organic and inorganic materials. Which of these list of compounds from food is an Organic material? A.Glucose ( C 6 H 12 O 6 ) B.Ammonia ( NH 3 ) C. Nitrate ( NO 3 ) D. B and C

Answer: A. Glucose ( C 6 H 12 O 6 )

As food is churned by the muscular force of the Stomach it will turn into a smoothie substance called Chyme. This process of digestion is known as – F. Physical digestion G. Chemical digestion H. Mechanical and Chemical digestion I. I need to study more about this…

Answer: F. Physical digestion

Acids, gastric juices and more enzymes continue to aid in the breaking down of food molecules in the stomach and small intestines. This digestion process is called – A.Mechanical digestion B.Physical digestion C.Chemical and Mechanical digestion D.Chemical digestion

Answer: D. Chemical digestion