The
Digestive SystemThe digestive system is a group of organs that
break down the chemical components of food, through the use of
digestive juices, into tiny nutrients which can be absorbed to
generate energy for the body. This system also builds and replaces
cells and tissues, which are constantly dying. Digestion begins
in the mouth with the teeth, which chew the food into small particles.
The tongue, a powerful muscle, detects "good" and "bad"
flavors in food and manipulates the food between the teeth for
chewing. Saliva, a watery fluid which lubricates chewing and swallowing,
begins the process of digestion. The digestive system begins in
the mouth, continues in the pharynx (throat) and esophagus and
into the stomach, small and large intestines, the rectum and the
anus. Food is chewed, pulped and mixed with saliva to become a
soft mass which will easily travel down the esophagus. The tongue
traps the food and forces it into the throat, which is a mass
of muscles and tissues which transports food into the "gut"
area for final processing and distribution. The throat closes
the top of the breathing pipes, but if the food accidentally enters
these pipes, it goes down the "wrong way" and must be
coughed up before the body chokes or asphyxiates. As food passes
through the body, it is mixed with an unbelievable amount of chemicals,
which break it down into small units that can be absorbed into
the blood and lymph systems. Some is used for energy, some as
building blocks for tissues and cells, and some is stored for
future or emergency use. The liver and the pancreas also secrete
digestive juices that break down food as it passes through the
digestive ducts. Not all that we eat can be digested, so the waste
is disposed of in an efficient way.