1. Digestive Function
Digestive system: the organ system that processes food and then voids it
Ingestion: intake of food
Digestion: mechanical, chemical breakdown of food so it is useable by body
Absorption: uptake of nutrients to be delivered by the blood and lymph
Defecation: voiding of undigested residue

2. Digestion location
Mesenteries: loose connective tissue that suspend the intestine and stomach, this causes freedom of movement while processing food
Most of digestion process occurs under the diaphragm in the stomach and intestine

3. Mouth Oral cavity: most of the mechanical processing occurs here
Process of chewing mixes food with saliva that contains enzymes that break down simple starches to be absorbed by vessels in cheek wall (Bolus)
Know the lingual Papillae
Function and types of teeth, fig 25.6

4. Swallowing
The pharynx starts the process as food passes the upper esophageal sphincter closes, allowing food to enter esophagus without air
As food passes through the esophagus smooth muscle that surrounds the esophagus contract in a wave like motion called peristalsis to push food down

5. Stomach The main function is to mix bolus with stomach acid (Chyme)
Chemical and mechanical digestion occur in the stomach
J-shaped organ with the lesser and greater curvature
Broken down into 4 regions cardiac, fundus, corpus, and pyloric

6. Stomach The walls made of several types of cells
Mucous cells: produce thick mucus layer that protects tissue from stomach acid
Stem cells: cells that are in constant production to replace cells that die
Parietal cell: produce acid, intrinsic factor
Chief cells: produce pepsinogen
Enteroendocrine cells: produce hormones that regulate digestion

7. Secretions Stomach acid: high concentration HCl with a Ph of 0.8
Pepsinogen: activated by HCl and changes into pepsin to digest protein
Intrinsic factor: key for Vit B12 uptake

8. Vomiting Vomiting: forceful ejection of chyme
Controlled by the emetic center found in the medulla oblongata
Nausea: sense of stomach discomfort
Retching: precedes vomiting, thoracic expansion and abdominal contraction dilates esophagus and relaxes lower esophageal sphincter, chyme travels up but settles in stomach

9. Vomiting
Vomiting occurs when abdominal contraction and thoracic pressure force the upper esophageal sphincter open
Projectile vomiting: is the sudden onset of vomiting without nausea and retching