1. Digestive System

2. Digestive System
The digestive system breaks down food both mechanically and chemically in order to release nutrient that the body’s cells can absorb and use.

3. Mouth & Salivary Glands
Teeth grind, hold, tear and chew
Tongue moves food, aids in swallowing = forms a bolus (ball of food)
Pharynx receives food (also air from nose)
Salivary glands-secrete saliva which contains enzymes (breaks down food more)
(mechanical digestion)
(chemical digestion)

4. Esophagus Muscular tube connecting mouth to stomach
Peristalsis (wave-like contractions) push food down
(mechanical digestion)

5. Stomach
Acidic environment (digestive juice containing enzymes breaks down food)
Sphincters at start and end of stomach are muscles that control movement of food in/out of stomach
Muscle layers contract to churn and mix food
Mucus part of stomach lining = protects the stomach from digestive juices
Some absorption occurs here (water, alcohol and aspirin)
(chemical digestion)
(mechanical digestion)

6. Small Intestines
7m long & large surface area due to finger-like projections called villi (where nutrients are absorbed into the blood)
Where most of the nutrient absorption occurs
Site of chemical digestion (including protein & carbohydrate digestion)
Fat digestion starts here (aided by liver and pancreas)
Pancreatic juices from pancreas & bile from liver enter here

7. Side note: Celiac Disease
Autoimmune disease: cannot eat gluten
Villi that lines small intestines are damaged by gluten protein
Prevents nutrient absorption.

8. Accessory Organs
Organs that are involved in digestion, but are not part of the continuous muscular tube of the digestive tract
Include:
Liver
Gall bladder
Pancreas
Do not directly digest food themselves… only contribute to the process!

9. Liver Produces bile for fat digestion in intestines
Stores carbohydrates & eliminates harmful substances (detoxifier)

10. Gall Bladder Stores and concentrates bile from liver
Releases bile into small intestine

11. Pancreas
Produces pancreatic juice contains enzymes to digest nutrients.
Makes bicarbonate to help lower acidity of stomach
Pancreatic juices enter the small intestine at its upper part.
Releases hormones to control blood sugar levels.

12. Large Intestines (Colon)
1.5m long
Food is no longer broken down by this point.
Absorbs water (mostly), vitamins and minerals
Secretes mucus to help with movement of food
Stores unused solid material till brain tells it to be voided
32 hours for food to pass!

13. Rectum Final straight portion of the large intestine
Stores solid waste and controls its release