Digestive System Overview

Human Food Consumption

• Humans consume 1 to 2.7 kg of food daily.
• Approximately 365 kg annually per person.
• Over a lifetime, more than 28,800 kg.

Digestive System Composition

• Comprised of ten organs covering nine meters.
• Contains over 20 specialized cell types.
• Functions to transform food into nutrients and energy.

Main Components

1. Gastrointestinal Tract
   • Twisting channel with an internal surface area of 30-40 square meters.
   • Comparable to half a badminton court.
2. Pancreas, Gallbladder, Liver
   • Break down food with special juices.
3. Enzymes, Hormones, Nerves, Blood
   • Collaborate to break down food and modulate digestion.
4. Mesentery
   • Supports and positions digestive organs in the abdomen.

Digestive Process

Initial Stage

• Begins before food reaches the tongue.
• Mouth glands produce saliva (1.5 liters daily).
• Chewing and saliva form food into a bolus.
• Saliva enzymes break down starch.

Esophagus

• 25 cm long tube.
• Peristalsis: Muscular contractions propel bolus to stomach.

Stomach

• Muscular walls break bolus into chunks.
• Hormones trigger release of acids and enzymes.
• Pancreas, liver, gallbladder prepare digestive juices and bile.

Small Intestine

• Chyme Formation: Bolus becomes frothy liquid after 3 hours in stomach.
• Duodenum: Bile dissolves fats for digestion by pancreatic and intestinal juices.
• Enzymes breakdown fats into fatty acids, proteins into amino acids, carbohydrates into glucose.
• Jejunum and Ileum: Villi increase absorption surface area.
• Nutrients absorbed into bloodstream.

Large Intestine (Colon)

• Processes leftover fiber, water, dead cells.
• Drains remaining fluid, forms stool.
• Stool moves into rectum.
• Expelled through the anus.

Digestion Duration

• Entire process lasts 30 to 40 hours.