This is a collective name used to describe the
alimentary canal, some accessory
organs and a variety of digestive processes, which take place at different
levels in the canal to prepare food eaten in the diet form for absorption.
alimentary canal, some accessory
organs and a variety of digestive processes, which take place at different
levels in the canal to prepare food eaten in the diet form for absorption.
The activity in the digestive system that aid absorption
of food [nutrients] includes
of food [nutrients] includes
1. Ingestion
2. Propulsion
3. Digestion
4. Absorption and
5. Elimination.
Alimentary Canal: this starts from the mouth
and continues through the pharynx, oesophagus, stomach, small and large
intestine, rectum and anus.
and continues through the pharynx, oesophagus, stomach, small and large
intestine, rectum and anus.
Accessory glands: these include the salivary
glands, the pancreas and the liver. Most of these glands synthesis digestive
enzymes that are involved in the chemical breakdown of food.
glands, the pancreas and the liver. Most of these glands synthesis digestive
enzymes that are involved in the chemical breakdown of food.
Metabolism: this is the sum total of
chemical activities in the body. It consist of two groups of processes-
Anabolism and Catabolism.
chemical activities in the body. It consist of two groups of processes-
Anabolism and Catabolism.
The activity in the digestive system can be grouped
under five main heading.
under five main heading.
1. Ingestion:
This is the taking of food into the alimentary canal
This is the taking of food into the alimentary canal
2.Propulsion:
This mixes and moves the contents alone the alimentary tract.
This mixes and moves the contents alone the alimentary tract.
3. Absorption: The uptake of nutrient molecules into the epitheliac
cells of the digestive tract and then into the blood stream or hymph.
cells of the digestive tract and then into the blood stream or hymph.
4. Digestion: This is the process where
the digested food could pass through the walls of some organs of the alimentary
canal into the blood and lymph capillaries for ciculaiton and use by the cells.
the digested food could pass through the walls of some organs of the alimentary
canal into the blood and lymph capillaries for ciculaiton and use by the cells.
5. Elimination:Food substance that have
been eaten but cannot be digested and absorbed are excreted from the alimentary
canal as faeces by defection
been eaten but cannot be digested and absorbed are excreted from the alimentary
canal as faeces by defection
Characteristic of the gastrointestinal wall
(Intestinal layers)
(Intestinal layers)
1. Serosa
2.A longitudinal muscle layer
3.A circular muscle layer
4.Submucosa
5. Muccus
