Digestive System Overview

Overview of the Digestive System

• The digestive system is a complex process by which the body breaks down and absorbs nutrients from food.
• It involves the coordination of multiple organs and enzymes to convert food into energy and nutrients.

Organs of the Digestive System

• Mouth:
  • Food is broken down mechanically by chewing and chemically by salivary enzymes.
  • Saliva contains amylase, which breaks down carbohydrates.
• Esophagus:
  • A muscular tube that transports food to the stomach.
  • Uses peristalsis (muscular contractions) to move food.
• Stomach:
  • A sac-like organ that secretes digestive enzymes and acids.
  • Gastric juices break down proteins and fats.
  • Churning action mixes food with stomach secretions.
• Small Intestine:
  • A long, thin tube where most nutrient absorption occurs.
  • Walls are lined with finger-like projections (villi) that increase surface area.
• Pancreas:
  • Produces digestive enzymes and hormones (e.g., insulin).
  • Secretions enter the small intestine to aid in nutrient absorption.
• Liver:
  • Produces bile, which emulsifies fats and aids in fat absorption.
  • Filters blood and detoxifies the body.
• Gallbladder:
  • Stores and concentrates bile from the liver.
  • Releases bile into the small intestine to aid in fat absorption.
• Large Intestine:
  • Also known as the colon, it absorbs water and electrolytes.
  • Houses a diverse community of gut bacteria (microbiome).

The Digestive Process

• Ingestion: Food is taken into the mouth.
• Mechanical digestion: Food is broken down into smaller pieces by chewing and grinding.
• Chemical digestion: Enzymes break down food into smaller molecules (e.g., carbohydrates, proteins, fats).
• Absorption: Nutrients are absorbed into the bloodstream through the walls of the small intestine.
• Elimination: Waste products are eliminated from the body through the anus.

Other Important Concepts

• Gastrointestinal motility: The movement of food through the digestive system.
• Gastrointestinal hormones: Hormones that regulate digestion, such as gastrin and secretin.
• Microbiome: The community of microorganisms that inhabit the digestive system.