Anatomy and Physiology: The Digestive System

Digestive System Structure and Function

Digestive system

The digestive system serves to supply constant nutrients which provide energy and building blocks to every body cell. This is achieved by the breaking down of food into small enough particles to pass through the cell membrane, known as digestion; and transference of these small particles to the circulatory system to be carried around the body, known as absorption.tmp696775

Organisation of the digestive system:

Two group of organs:

  • Digestive tract – a continuous passageway through the body
    • Mouth
      • Receives food
      • Prepares food for digestion using teeth and tongue
      • Begins digestion of starch using saliva
    • Pharynx (throat)
      • Swallowing reflex
    • Esophagus
      • Muscular tube carrying food to the stomach
    • Stomach
      • Storage pouch
      • Digestive organ using gastric juice
      • Churn food before it enters the small intestine
    • Small intestine
      • Receives digestive juices from liver and pancreas for digestion
      • Absorbs digested food through its walls
    • Large intestine
      • Storage and elimination of undigested waste
      • Reabsorption of water


  • Accessory Organs – release substances into the digestive tract through ducts
    • Liver
      • Production of bile
        • Breaks up fats
        • Aids fat absorption from small intestine
    • Gallbladder
      • Stores bile from the liver
    • Pancreas
      • Produces enzymes to digest fats, proteins, carbohydrates and nucleic acid
      • Produces alkaline fluid to neutralise stomach acids to protect the digestive tract