The main function of the digestive system is to break down food into mole-
cules small enough for the body to absorb. The nutrients are absorbed in the
body and used for energy. Our digestive system goes through eight basic
How long is the average digestive system?
-Mark off 3 inches (7 cm) of string to represent your mouth.
-Add 10 inches (25 cm) for your esophagus.
-Add 6 inches (15 cm) for your stomach.
-Add 18 feet (5.5 m) for your small intestine.
-Add 5 feet (1.5 m) more for your large intestine.
! Ingestion â¨ The first function of the digestive system is ingestion, or the intake of food.
The mouth is responsible for this function, as it is the orifice through which
all food enters the body. The mouth and stomach are also responsible for
the storage of food as it is waiting to be digested. This storage capacity al-
lows the body to eat only a few times each day and to ingest more food than
it can process at one time.
! ! !
Absorption â¨ Once food has been reduced to its building blocks, it is ready for the body
to absorb. Absorption begins in the stomach with simple molecules like wa-
ter and alcohol being absorbed directly into the bloodstream. Most absorp-
tion takes place in the walls of the small intestine, which are densely folded
to maximize the surface area in contact with digested food. Small blood and
lymphatic vessels in the intestinal wall pick up the molecules and carry
them to the rest of the body. The large intestine is also involved in the ab-
sorption of water and vitamins B and K before feces leave the body. â¨ ! Excretion â¨ The final function of the digestive system is...