Functions of the Digestive System

Function of Digestive System

• Ingestion is the first process of taking food and liquid into the mouth.
• The Gastrointestinal Tract (GIT) and accessory organs secrete approximately 7 liters of water, acid, enzymes, and buffers into the lumen of GIT daily.

Mixing and Propulsion

• Involuntary contraction and relaxation of smooth muscles achieve mixing of food and secretion through peristalsis movement.

Digestion

• There are two types of digestion: mechanical digestion (occurs in GIT organs) and chemical digestion (occurs through enzymes and secretions).

Absorption

• Digested substances are absorbed and pass into the blood and lymph.

Defecation

• Undigested substances, wastes, sloughed cells, and bacteria are expelled through the anus.

Gastric Juice Components

• Hydrochloric acid is secreted from parietal cells, providing an acidic medium and killing bacteria.
• Pepsin is secreted from chief cells for protein digestion.
• Mucus is secreted from epithelial cells.

Digestive Enzyme Secretion

• Enzymes help digest carbohydrates, fats, and proteins.
• Absorption of water, electrolytes, metals, and nutrients occurs.

Large Intestine

Anatomy

• The large intestine is divided into the following parts:
  • Caecum: connected to the small intestine by the ileocecal sphincter, with a small vermiform appendix.
  • Colon: consisting of:
    • Ascending colon.