This document discusses the human digestive system and nutrient absorption. It describes the key functions of the mouth, esophagus, stomach, liver, pancreas, small intestine and large intestine. The mouth mechanically breaks down food and adds saliva. The stomach initiates protein digestion with hydrochloric acid and pepsin. The liver and pancreas produce bile salts and digestive enzymes that aid in digestion in the small intestine, where most nutrients are absorbed. The large intestine absorbs water and hosts bacterial fermentation.

1. Nutrition, Gas Exchange, &
Circulation: Bioenergetics

2. Bioenergetics

3. Important Nutrients

4. Food Guide Pyramid

5. Work It!

6. Nutritional Information
http://www.wholefoodsmarket.com/healthinfo/lifestyle_women.html

7. How Organisms make Energy

8. The Goal of
Digestion

9. The Human Digestive System

10. The Art of Swallowing

11. Super Spit..for Real!!

12. A Close look at the Stomach

13. Important Organs

14. Nutrient
Absorption in
the Small
Intestine

15. Surface area to Volume…
A Fundamental Constraint of Biological
Systems

16. Nutrient Breakdown

17. The Flow of Nutrients

18. Functions of Digestive Organs
• Mouth: Foodstuffs are broken down mechanically by chewing and saliva is added as a
lubricant. In some species, saliva contains amylase, an enzyme that digests starch.
• Esophagus: A simple conduit between the mouth and stomach - clearly important but only
marginally interesting compared to other regions of the tube. .Parastalsis
• Stomach: Where the real action begins - enzymatic digestion of proteins (pepsin) initiated
(HCl) and foodstuffs reduced to liquid form.
• Liver: The center of metabolic activity in the body - its major role in the digestive process is to
provide bile salts to the small intestine, which are critical for digestion and absorption of fats.
• Pancreas: Important roles as both an endocrine and exocrine organ - provides a potent mixture
of digestive enzymes (pancreatic fluid) to the small intestine which are critical for digestion of
fats, carbohydrates and protein.
• Small Intestine: The most exciting place to be in the entire digestive system - this is where the
final stages of chemical enzymatic digestion occur and where almost almost all nutrients are
absorbed.
• Large Intestine: Major differences among species in extent and importance - in all animals
water is absorbed, bacterial fermentation takes place and feces are formed. In carnivores, that's
about the extent of it, but in herbivores like the horse, the large intestine is huge and of critical
importance for utilization of cellulose.

19. Recap

20. Comparative Anatomy: Vertebrates

21. Comparative Anatomy: Inverts