Digestive SystemHB&H Chapter 3.3

Pages 82-87

Functions

• Digestive system fills three roles…1. Breaks food down into molecules the body

can use2. Absorbs molecules into the blood3. Eliminates wastes from the body.

Digesting

• Digestion is the process by which you’re body breaks down food into nutrient molecules

• Occurs in two ways…– Mechanical– Chemical

Mechanical Digestion

• Physically breaking down food into smaller, manageable pieces– Chewing with teeth– Churning of the

stomach.

Chemical Digestion

• Chemicals produced by the body break food into chemical building blocks– Starch in bread is

broken down to sugar molecules

• Enzymes are proteins the speed up chemical reactions.

Chemical Digestion

• Chemical digestion occurs when…– Saliva mixes with food

in mouth– Digestive juices in the

stomach (such as Pepsin and hydrochloric acid) break food down into liquid form.

Down the Wrong Tube

• Esophagus is the muscular tube that leads from mouth to stomach and lungs

• Epiglottis is a flap of tissue that covers your wind pipe

Down the Hatch

• Lined with Mucus, which makes food easier to swallow– Helps protect from bacteria

• Muscles of esophagus contract to move food along, called Peristalsis.

Stomach

• Holds food until digested (mechanically & chemically)– Can hold about 2 liters

• Leads to small intestine• Coated with mucus – Cells are replaced

quickly.

Exit Pass

What are 2 of the 3 functions of the digestive system?