1. 3.3 DIGESTIVE SYSTEM

2. Digestive System One long muscular tube
Approximately 10 m in length (adult)
Generally a one-way tract
Break down the food we eat into small molecules that can be metabolized (used for energy) by individual cells in our body
We must eat food that contains nutrients
Ex: Carbohydrates, lipids, proteins, vitamins, minerals, water

3. Digestive System 4 processes Ingestion – taking in of food
Digestion – breakdown of food into small components
Absorption – cells soak up digested material
Egestion – elimination of waste from the body

4. Digestive System - Structure

5. MOUTH Structure Function Teeth, tongue, salivary glands, saliva
Teeth and tongue mechanically break down food
Salivary glands secrete enzymes that break apart the food. Saliva softens food

6. ESOPHOGUS Structure Function Muscular tube connecting mouth to stomach
Smooth muscle tissue contracts/relaxes to move food slowly along
Peristalsis – Rhythmic contractions independent of gravity

7. STOMACH Structure Function Muscular bag that can stretch
3 muscle layers
Muscle layers contract and mix food with gastric juices (HCl, mucous)

8. SMALL INTESTINE Structure Function 7m long, 2.5cm wide
Duodenum, jejunum, ileum
Folded to increase surface area
Digestion of food is completed here
Nutrients are absorbed into the blood stream

9. LARGE INTESTINE Structure Function 1.5m long, 8cm wide
The lining absorbs water from any indigestible food
Solid matter excreted as feces from anus

10. RECTUM Structure Function 12 cm long Begins at end of sigmoid colon
temporary storage for feces
When urge to defecate, rectum shortens and expels feces
If urge is ignored, feces moves back up colon where more water is absorbed and constipation occurs

11. ANUS Structure Function External opening of the rectum
Comprised of 2 sphincters
Inner sphincter is involuntary
Outer sphincter is voluntary
Control the exit of feces during defecation

12. ACCESSORY ORGANS Liver Gallbladder Pancreas
produce/ release chemicals that aid in the breakdown of food

13. Homework
P 82 # 3-5
Digestive CROSSWORD
Digestive System WKST