THE
DIGESTIVE
SYSTEM
, DIGESTIVE SYSTEM
• Has a general structure which is modified at different levels to provide for the
2 occurring at each level.
processes
• Breaks down the foods eaten until they are in a form suitable for absorption: amino
acids, mineral salts, fat and vitamins.
• Chemical substances which effect these changes are secreted into the canal by
specialised glands, some
• in the walls of the canal
• outside the canal with ducts leading into it.
,• Activities in the digestive system are:
1. Ingestion: process of taking food into the alimentary tract.
2. 3
Propulsion: moves the contents along the alimentary tract.
3. Digestion: Consists of:
mechanical breakdown of food by, e.g. mastication (chewing)
chemical digestion of food by enzymes present in secretions produced by glands & accessory
organs of the digestive system.
4. Absorption: process by which digested food substances pass through the walls
of some organs of the alimentary canal into the blood and lymph capillaries for
circulation round the body.
5. Elimination: Excretion of food substances which have been eaten but cannot be
digested and absorbed.
, 4
ORGANS OF THE DIGESTIVE SYSTEM
DIGESTIVE
SYSTEM
, DIGESTIVE SYSTEM
• Has a general structure which is modified at different levels to provide for the
2 occurring at each level.
processes
• Breaks down the foods eaten until they are in a form suitable for absorption: amino
acids, mineral salts, fat and vitamins.
• Chemical substances which effect these changes are secreted into the canal by
specialised glands, some
• in the walls of the canal
• outside the canal with ducts leading into it.
,• Activities in the digestive system are:
1. Ingestion: process of taking food into the alimentary tract.
2. 3
Propulsion: moves the contents along the alimentary tract.
3. Digestion: Consists of:
mechanical breakdown of food by, e.g. mastication (chewing)
chemical digestion of food by enzymes present in secretions produced by glands & accessory
organs of the digestive system.
4. Absorption: process by which digested food substances pass through the walls
of some organs of the alimentary canal into the blood and lymph capillaries for
circulation round the body.
5. Elimination: Excretion of food substances which have been eaten but cannot be
digested and absorbed.
, 4
ORGANS OF THE DIGESTIVE SYSTEM
