Digestive System

Function• Break down food into particles

the body can use

• Particles are absorbed into blood and carried throughout body

• Wastes are removed from the body

Organs Involved

1. Mouth

2. Esophagus

3. Stomach

4. Pancreas

5. Liver

6. Gallbladder

7. Small Intestine

8. Large Intestine

9. Rectum

• Digestion-process where body breaks down food

• 2 Kinds:1) Mechanical-physically broken down

2) Chemical-chemicals break food down

–Enzymes-proteins that speed up chemical reactions in the body

»Pepsin-breaks down protein

»Amylase-breaks down starch

• Absorption-nutrients pass though wall of digestive system into blood. The circulatory system will then carry the nutrients to the cells of the body.

• Saliva-fluid released by mouth; contains enzymes

The Mouth• Mechanical digestion starts with

teeth

• Saliva mixes with food moistening

• Chemical digestion also starts breaking down starch into sugar

• Salivary Glands-produce Saliva

Esophagus• Muscular tube that connects mouth

to stomach, lined with mucus

• 2 openings at back of mouth-one to trachea, one for esophagus

• Epiglottis-flap covering trachea

• Peristalsis-involuntary waves of muscle contractions to push food along

Stomach• J-shaped Pouch

• Mechanical digestion occurs here when strong muscles squeeze food. MOST mechanical digestion occurs here.

• Chemical digestion occurs at same time-acids and other chemicals break down food

Stomach cont…• Contains hydrochloric acid-a very strong

acid which would burn through clothing but without this acid, your stomach would not work properly.

• Has a mucus lining-coats and protects your stomach

• Your stomach produces a new lining every 2 days.

Stomach cont…• Heartburn is when some of the

stomach acid starts to move back up the esophagus causing a burning sensation in chest.

• Stomach ulcer-when a person produces too much stomach acid and it burns a hole in the stomach lining.

Small Intestine• Most chemical digestion occurs and

absorption of nutrients takes place

• Covered with villi-tiny finger shaped structures with capillaries inside

• Capillaries inside villi pick up nutrients so blood can carry to rest of body

Cross Section of Small Intestine

Liver, Gallbladder and Pancreas(Food does not pass through these organs)

• Liver-largest and heaviest internal organ inside the body

–Produces bile-substance that breaks down fat

• Gallbladder-stores bile

• Pancreas-produces chemicals that break down starches, proteins and fats

Large Intestine• Removes water from undigested

material

• Contains helpful bacteria that produce vitamins

Large Intestine Cont…

Rectum

• Waste is compressed into a solid form

• “Holding tank” for wastes until they can be removed

• Removed from the body through the anus-a muscular opening at the end of the rectum