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

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. 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. 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

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