Overview
This lecture focuses on the functional anatomy of the digestive system, summarizing the main organs, their roles, and key processes involved in digestion.
Digestive System Overview
- The digestive system breaks down food, absorbs nutrients, and eliminates waste.
- It is divided into the alimentary canal (GI tract) and accessory organs.
Alimentary Canal (GI Tract)
- The alimentary canal includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.
- Food is mechanically and chemically broken down as it moves through these organs.
- Peristalsis is the wave-like muscle contraction that moves food along the tract.
Accessory Digestive Organs
- Accessory organs include the salivary glands, liver, gallbladder, and pancreas.
- These organs secrete enzymes and fluids that aid in digestion but do not directly contact food in most cases.
Major Digestive Processes
- Ingestion is the act of taking food into the mouth.
- Propulsion moves food through the digestive tract, mainly via peristalsis.
- Mechanical digestion physically breaks down food, such as chewing and stomach churning.
- Chemical digestion uses enzymes to break food into smaller molecules.
- Absorption is the movement of nutrients from the GI tract into the blood or lymph.
- Defecation is the elimination of indigestible substances as feces.
Key Terms & Definitions
- Alimentary canal — the continuous tube from mouth to anus where digestion occurs.
- Accessory organs — organs that aid digestion by producing enzymes and fluids.
- Peristalsis — muscle contractions that push food through the digestive tract.
- Mechanical digestion — physical breakdown of food into smaller pieces.
- Chemical digestion — enzymatic breakdown of food into absorbable molecules.
- Absorption — process by which nutrients enter the blood or lymph.
- Defecation — expulsion of undigested waste from the body.
Action Items / Next Steps
- Review the anatomy and functions of each major organ in the digestive system.
- Study the sequence and role of each digestive process.
- Prepare for quiz on digestive system structure and function.