1. Mouth:
* Chewing: Teeth break down food into smaller pieces, increasing surface area for digestion.
* Saliva: Contains enzymes (like amylase) that begin the breakdown of carbohydrates.
2. Esophagus:
* Peristalsis: Muscular contractions move food down the esophagus to the stomach.
3. Stomach:
* Churning: Muscle contractions mix food with gastric juices.
* Gastric Juices: Contain hydrochloric acid (HCl) to break down proteins and enzymes like pepsin for further protein breakdown.
* Partially Digested Food: The stomach releases a thick liquid called chyme into the small intestine.
4. Small Intestine:
* Nutrient Absorption: The majority of nutrient absorption occurs here.
* Duodenum: The first part, receives chyme from the stomach, and receives bile from the liver and pancreatic enzymes from the pancreas.
* Jejunum: The middle section, where most nutrient absorption takes place.
* Ileum: The final section, absorbs vitamin B12 and bile salts.
* Enzymes: Enzymes from the pancreas (amylase, lipase, protease) further break down carbohydrates, fats, and proteins.
* Bile: Produced by the liver and stored in the gallbladder, bile emulsifies fats, aiding in their digestion.
5. Large Intestine (Colon):
* Water Absorption: Most of the remaining water is absorbed here.
* Waste Processing: Undigested food and bacteria are processed into feces.
6. Rectum:
* Feces Storage: Stores waste before elimination.
7. Anus:
* Elimination: The final exit point for waste.
Important Note: The liver, gallbladder, and pancreas are vital for digestion, but food does not directly pass through them. These organs produce and release substances (bile, enzymes) that aid in digestion in the small intestine.
