The Digestive System

3.5 & 3.6

Stages of Food Processing

• ingestion

• digestion

• absorption

• egestion

Ingestion

• teeth: physical breakdown of food• salivary glands: amylase in saliva

breaks down starch (chemical digestion)

• tongue: forms bolus, pushes it back to pharynx

• esophagus: peristalsis moves bolus down http://www.youtube.com/watch?v=h0E9ITyRlh0

Digestion (Stomach)

Digestion (Stomach)

• gastric juices: hydrochloric acid + enzymes (e.g., pepsin)

• mucus: protects lining of stomach from damage

• chyme = partly digested food, water, and gastric juice that enters the small intestine

Digestion (Duodenum)

Digestion (Duodenum)

• bile (produced in liver, stored in gall bladder): emulsifies fat

• lipase, amylase, trypsin (produced in pancreas): digest fat, starch, protein

• maltase, peptidases (produced in duodenum): digest maltose, polypeptides

Absorption (Small Intestine)

Small Intestine

• up to 7 metres in length (25 cm of which is duodenum), 2.5 cm wide

• villi & microvilli increase surface area for absorption

Large Intestine

• 1.5 metres long, 5 cm in diameter

• absorbs water• helpful bacteria

produces vitamins K and B

Egestion

Animations

• Process of digestion:• http://www.youtube.com/watch?v=Z7xK

YNz9AS0• Animation & Quiz:• http://highered.mcgraw-hill.com/sites/00

72495855/student_view0/chapter26/animation__organs_of_digestion.html

Is it Art?