1. THE DIGESTIVE SYSTEM
The digestive system is the organ system that takes in food, digests it, and excretes the remaining waste.
The digestive system is made up of the digestive tract and accessory organs.
Nelson Science
The parts of the digestive system in humans are shown in the diagram below.
digestive system

2. Parts of the Human Digestive System
Mouth:
teeth and tongue – mechanically digest food
saliva – chemical digestion and softens food
bolus (ball of chewed food) swallowed
(O)esophagus:
long tube that connects mouth to stomach
food passes down the tube by involuntary contraction of smooth muscles called peristalsis

3. 3. Stomach:
muscles contract and continue churning food in mechanical digestion
contains special cells that secrete digestive enzymes and acids to break down food chemically
lined with mucus to protect it from acids

4. 4. Intestines:
divided into 2 parts:
Small Intestine:
~ 6 m long
more digestion of food occurs here
where absorption of nutrients happens
Large Intestine (Colon):
1.5 m long but larger than small intestine
water gets absorbed
solid material left is waste to be removed as feces

5. Rectum:
holding area for feces until ready to pass out of system
6. Anus:
sphincter (ring of muscles) that opens to allow feces to exit digestive system
only opens when rectum is full
7. Accessory Organs:
other organs that supply digestive enzymes to the small intestine that help in digestion
pancreas – produces insulin and glucagon to control blood sugar levels
liver - produces bile to help in digestion
gall bladder – stores and releases bile into small intestine