THE GASTOINTESTINAL
SYSTEM
BY Nyakallo Motlalane
Objectives
• Describe the digestive system
• Describe the functions if the digestive system
• Identify the organs of the alimentary canal
Introduction to the digestive system
• The digestive system describes the alimentary canal, its
accessory organs and a variety of digestive processes that
prepare food eaten in the diet for absorption.
• It is the digestive tract or passageway of the gastrointestinal
system that leads from the mouth to the anus.
Digestive processes
• Ingestion: taking food into the alimentary canal
• Propulsion: this mixes and moves the food along the alimentary tract
• Mechanical digestion: mastication or chewing
• Chemical digestion: food broken down by enzymes present in
secretions produced by the glands and accessory organs
• Absorption: digested food pass through some walls of the organs into
the blood and lymph capillaries for circulation and use by body cells.
• Elimination: undigested food cannot be absorbed and gets excreted
from the alimentary canal as faeces.
What breaks down in the alimentary canal?
• The digestive system breaks down food into simple nutrients such as
carbohydrates in the mouth by salivary amylase , fats once it reaches
the small intestines by the pancreas and proteins
• These can the be absorbed into the blood, so the body can use them
for energy, growth and repair.
Organs of the digestive system