Digestive System

Digestive System

Getting Ready Activity

Materials: (per pair)1 piece of paper1 pen

Instructions:• Going back and forth between you and your

partner, try to map the journey that food takes as it goes through the digestive system

• Be as detailed as possible (try to mention at least 8 organs)

• You have one minute to complete the activity

Language Connection• The digestive tract is often called the ‘gastrointestinal’ tract,

or GI tract for short• Gastro (greek) = stomach• Intestinal = intestines

Gastric – of or relating to the stomachGastronomy – study of the culture of foodGastric bypass – surgery that bypasses the stomachGastroenteritis – inflammation (infection) of the stomach

Digestive System• The organ system that is made up of the mouth,

esophagus, stomach, intestines, liver, pancreas, and gall bladder

• The system that takes in (ingestion), breaks up (digestion), absorbs (absorption), and eliminates wastes (egestion)

The GI Tract

• Essentially one long tube with two openings (mouth and anus) with accessory organs

• Gastrointestinal tract:Mouth Esophagus Stomach Small Intestine

Large Intestine Rectum Anus

• Accessory organs:Salivary glandsLivergall bladderpancreas

Tissues of the Digestive System• The entire digestive tract is lined with epithelial tissue• Goblet cells secrete mucus• Mucus protects the tract from digestive enzymes, and

lubricates the passage for the food• The tract also contains

muscle which allows the food to be pushed alongthe tract (peristalsis)

Warning... Gross video ahead

Mouth• Starting point of digestion• Mechanical digestion:

Mouth and Tongue – break apartFood

• Chemical digestion:Saliva – Saliva contains enzymes that break

down food. Saliva also lubricates the food.• Once broken up, the food (now a bolus) is swallowed

Esophagus• Long tube surrounded by muscle• The muscle contracts and relaxes

to push food along toward the stomach (peristalsis)

Stomach• Muscular organ that holds and churns food to continue

the process of digestion• Strong acids (Hydrochloric acid HCl) and enzymes are

secreted in the stomach to digest food• Acid that splashes up into the esophagus is the cause of

heartburn

Small Intestines• Small intestine is actually quite long – approximately 6m• Partially digested food that leaves the stomach is further

digested• Nutrients are absorbed

Large Intestines (Colon)• Large intestine are about 1.5m in length, but larger in

diameter than S. Intestine• Water is reabsorbed• Trillions of bacteria live in

your colon• They provide you with

vitamins (K, and biotin)

Warning – Frog picture ahead