Biology 38.2

38.2 The process of Digestion

Amylase

• Enzyme in saliva that breaks the chemical bonds in starches.

Esophagus

• Food tube connecting the mouth to the stomach.

Peristalsis

• Rhythmic muscular contractions that squeeze food through the esophagus into the stomach.

Stomach

• Large muscular sac that continues the mechanical and chemical digestion of food.

Chyme • Mixture of stomach fluids and food produced

in the stomach by contracting stomach muscles.

Small Intestine

• Digestive organ in which most chemical digestion takes place.

Pancreas• Gland that produces hormones that regulate

blood sugar; produces enzymes that break down carbohydrates, proteins, lipids, and nucleic acids; and produces sodium bicarbonate, a base that neutralizes stomach acid.

Liver

• Large organ just above the stomach that produces bile.

Villus

• Folded projection that increases the surface area of the walls of the small intestine.

Large Intestine

• Colon; organ that removes water from the undigested materials that pass through it.

Key Concept

• The digestive system includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. Several major accessory structures, including the salivary glands, the pancreas, and liver, add secretions to the digestive system.

Key Concept

• The function of the digestive system is to help convert foods into simpler molecules that can be absorbed and used by the cells of the body.