Digestion Process

Introduction

• New teeth allow for consumption of solid foods.

Digestion Begins in the Mouth

• Teeth grind food.
• Salivary glands under the tongue release saliva for breakdown and lubrication.

Journey Through the Gut

• Total journey takes about 12-13 hours.
• Food moves from the stomach to the small intestine and then to the large intestine.
• Peristalsis: Waves of contracting muscles that move food through the digestive tract.
  • Powerful enough to allow eating upside down.

Stomach

• Food enters through the top via a hole.
• The stomach is a muscular bag that churns, squashes, and squeezes food into liquid.
• Acids in the stomach help break down food.
• The stomach lining has mucus to protect itself from digestive acids, preventing ulcers.
• After 1 hour, food passes through the pyloric sphincter into the small intestine.

Small Intestine

• An 11-foot coiled tube where most nutrient absorption occurs.
• Lined with villi: tiny projections that increase surface area for absorption.
• Pancreas releases juice to neutralize stomach acid.
• Bile from the liver emulsifies fats into smaller droplets for easier absorption.
• After 1.5 hours, most nutrients are absorbed.

Large Intestine

• Food enters through the ileocecal sphincter.
• Remaining material is waste and dead gut cells.
• Main function: extract water from waste.
• Hosts beneficial bacteria that produce enzymes to break down complex carbohydrates.

Conclusion

• After about 12 hours, waste is expelled from the body.