1. Digestive system

2. Function of the digestive system
Supply chemical energy
Ex. Sugars are broken down to make ATP
Supply organic molecules
Need proteins so they can make their own proteins to catalyze reactions in the cell
Supply essential nutrients
Your body needs calcium to help build bones

3. Draw the outline of a person now!

4. Food is pushed along by peristalsis, rhythmic contractions of muscles in the wall of the canal
Valves called sphincters regulate the movement of material between compartments

5. The first stage- In the oral cavity
Mechanical - Teeth chew food
Chemical – Salivary glands: deliver saliva to lubricate food
Amylase – an enzyme that hydrolyzes starch
Mucin – glycoprotein that protects lining of mouth
Buffers
Antibacterial agents (ex. Lysozyme)

6. Pharynx and esophagus
The esophagus conducts food from the pharynx down to the stomach by peristalsis
Swallowing causes the epiglottis to block entry to the trachea, and the bolus is guided by the larynx, the upper part of the respiratory tract
Coughing occurs when the swallowing reflex fails and food or liquids reach the windpipe

7. Draw the oral cavity, pharynx and Esophagus
Put notes next to the structures and also determine what is broken down in this part of the digestive system
(use figure 887 for help)

8. Draw the stomach Add notes using page 886 Address these questions
What is the main function of the stomach
What is digested in the stomach
What are the enzymes and what are their functions

9. Stomach
The stomach stores food and secretes gastric juice, which converts a meal to acid chyme

10. Stomach – Gastric juice
HCl
Parietal cells secrete hydrogen and chloride ions separately
Pepsin
Chief cells secrete inactive pepsinogen - activated to pepsin when mixed with HCl
Mucus protects gastric juices from harming the stomach cells

11. Small intestine Main site of digestion and absorption
Digests lipids, proteins, carbohydrates and nucleic acids

12. Small intestine - Duodenum
Pancreatic secretions include
Bicarbonate
Neutralizes acidity
Enzymes
Trypsin
Chyotrypsin
*activated when in the duodnum
Gallbladder secretions
Bile (made in liver)
Digestion of lipids
Epithelial lining secretions
Digestive enzymes

13. Small intestines – jejunum and ileum
Absorption of nutrients and water
Able to do this because of the large surface area

14. Draw the small and large intestine
Address the Following
What is the main function
What is digested
What are the enzymes and what are their functions (if there are any)

15. Large intestine
Main function is to recover water