Digestive System Lecture Notes
1. Overview
The digestive system, also called the gastrointestinal (GI) tract or alimentary canal, is a long tube through
which food passes and is broken down for absorption into the body. It includes the mouth, pharynx,
esophagus, stomach, small intestine, large intestine, rectum, and anus.
2. Major Organs and Functions
- Mouth: Begins mechanical digestion through chewing and chemical digestion via saliva.
- Pharynx and Esophagus: Transport food from the mouth to the stomach.
- Stomach: Stores food and mixes it with gastric juices for digestion.
- Small Intestine: Major site for digestion and absorption of nutrients.
- Large Intestine: Absorbs water and electrolytes; forms and stores feces.
- Rectum and Anus: Control the elimination of feces.
3. Digestive Processes
The key processes include ingestion, propulsion, mechanical digestion, chemical digestion, absorption, and
defecation. Enzymes, acids, and muscular contractions help in the transformation of food.
4. Accessory Organs
The liver, pancreas, and gallbladder are not part of the GI tract but aid digestion.
- Liver: Produces bile for fat digestion.
- Gallbladder: Stores and concentrates bile.
- Pancreas: Secretes enzymes for digestion of carbohydrates, proteins, and fats.
5. Common Disorders
- Gastroesophageal reflux disease (GERD)
- Peptic ulcers
- Irritable bowel syndrome (IBS)
- Inflammatory bowel diseases (e.g., Crohn's disease and ulcerative colitis)
Digestive System Lecture Notes
6. Diagram of the Alimentary Canal