1. Functions of Gastrointestinal System

• Most of the food that is available consists of complex, large macromolecules, which are not directly usable as building blocks or energy resources
• We need to digest
  • to process food to convert complex molecules into amino acids, fatty acids, and simple sugars which we absorb into the blood stream
  • to extract and absorb vitamins, minerals and water from food and drinks
• Ingested food has to be mechanically processed, solubilised and moistened
  • Enzymes, HCl, bile, water and mucus need to be secreted and it all needs to be mixed and moved along

Main Processes

Ingestion

• Eating

Digestion

• Uptake, mechanical and chemical break down of food
• Location: partly in Mouth, mostly in Stomach and the Small Intestine

Secretion

• Enzymes and Bile into GI Duct
• Location: Mouth, Stomach, Small Intestine and Large Intestine

Absorption

• Uptake of products of digestion, water, minerals and vitamins into the blood stream
• Location: Small Intestine and Large Intestine

Motility

• Generation of movement throughout the tract
• The movements produced in the system serve several purposes:
  • To aid the breakdown of food
  • give the overall movement of the contents a preferred direction
  • help to knead the chyme