1. Human digestive system
After chewing and swallowing, it takes 5 to 10 seconds for food to pass down the esophagus to the stomach, where it spends 2 to 6 hours being partially digested.
Final digestion and nutrient absorption occur in the small intestine over a period of 5 to 6 hours.
In 12 to 24 hours, any undigested material passes through the large intestine, and feces are expelled through the anus.

2. The Digestive System How is food digested?
Purpose of the Digestive system:
Breaks down food into substances that cells can absorb and use.
How is food digested?
Breaking down of food into smaller piece
The mixing of food
Movement through the digestive tract
Chemical breakdown of the large molecules of food into smaller molecules

3. Nutrition Process by which organisms obtain and utilize their food.
There are two parts to Nutrition:
1. Ingestion- process of taking food into the digestive system so that it may be hydrolized or digested.
2. Digestion- the breakdown of food (either chemically or mechanically) in order to utilize nutrients

4. Types of Nutrients Micronutrients- vitamins, minerals, & water
Macronutrients- proteins, lipids, carbohydrates, etc…

5. Mouth Mechanical digestion - teeth Chemical digestion – saliva
Chewing mixes the food with saliva, from salivary glands around the mouth and face, to make it moist and easy to swallow = BOLUS
Enzymes in the saliva begin digestion of carbohydrates.
Epiglottis – flap of cartilage that blocks trachea when swallowing

6. Esophagus Muscular tube
It moves food by waves of muscle contraction called peristalsis.
Physically moving the food along to the stomach.
Mechanical Digestion

7. Stomach
The stomach lining produces strong digestive juices (HCl, pepsin)– chemical digestion
These create chemical reactions in the stomach, breaking down and dissolving its nutrients = CHYME
Digests proteins and fats in the stomach
Peristalsis = mechanical digestion

8. Small Intestine
Enzymes continue the chemical reactions on the food – chemical digestion
The nutrients are broken down small enough to pass through the lining of the small intestine, and into the blood (diffusion).
Digests proteins, fats, and carbohydrates.
Peristalsis = mechanical digestion

9. Absorption by Small Intestines
Absorption through villi & microvilli
finger-like projections
increase surface area for absorption

10. VILLI

11. Pancreas Accessory organ Food does not go through the pancreas
Produces chemicals to help break down macromolecules = chemical digestion
Also produces insulin = helps control blood sugar levels

12. Liver
Produces bile to help digest fat – Mechanical Digestion, fats are broken into smaller “fat globules”
Bile is stored in the Gall Bladder and released into the small intestine

13. Large intestines (colon)
Function
re-absorb water
(NO DIGESTION)
use ~9 liters of water every day in digestive juices
> 90% of water reabsorbed
not enough water absorbed
diarrhea
too much water absorbed
constipation

14. Large Intestine Solid materials pass through the large intestine.
These are undigestible solids (fibers).
Water is absorbed.
Vitamins K and B are reabsorbed with the water.
Rectum- solid wastes exit the body.

15. You’ve got company!
Living in the large intestine is a community of helpful bacteria
Escherichia coli (E. coli)
produce vitamins
vitamin K; B vitamins
generate gases
by-product of bacterial metabolism
methane, hydrogen sulfide