The digestive system is a series of hollow organs joined
in a long, twisting tube from the mouth to the anus. Inside
this tube is a lining called the mucosa. In the mouth, stomach, and small
intestine, the mucosa contains tiny glands that produce juices to help
digest food. In addition, there are two solid organs, the liver and pancreas,
involved in digestion. These organs produce digestive juices that reach
the intestine though small tubes. Parts of other organ systems such as
nerves and blood also play major roles in digestion.
The digestive system is involved in the process by
which food and fluids are broken down into smaller molecules that can
be absorbed into the blood and carried to cells throughout the body, building
and nourishing them, and providing the energy the body requires. It also
plays an important role in the excretion of toxic chemicals, pathogens,
and by-products of the digestive processes, and in balancing the absorption
and secretion of electrolytes and water.
The small intestine's mucosal cells have many special
systems that ensure the absorption of carbohydrates, protein, fats, vitamins,
water, and salt, making it one of the most important parts of the digestive
system. Digested molecules of food, as well as water and minerals, are
absorbed from the small intestine. The absorbed materials cross the mucosa
into the blood and are carried by the bloodstream to other parts of the
body for storage or further chemical change, providing the nourishment
the body needs in order to function. This part of the process varies with
different types of nutrients.
The small intestine (bowel) is divided into three parts:
the duodenum, jejunum,
and ileum. It is the longest part of the
digestive tract, beginning with the duodenum, which is connected to the
stomach, and ending with the ileocecal valve, which is connected to the
large intestine (colon). The jejunum follows the duodenum as the next
section of the small intestine, making up two-fifths of its length. After
the jejunum is the ileum, with no distinct point at which one ends and
the other begins. The ileum is narrower than the jejunum and its wall
is thinner. The ileocecal valve is the point at which the small intestine
ends and the large intestine begins. This valve prevents the backflow
of contents from the large intestine into the ileum.
This information
is provided as a general educational service
and is not intended to recommend any particular treatment plan
or to replace the advice of physicians. It is important that patients
seek and rely on the advice of a healthcare professional
about their individual medical conditions.
Inside
this tube is a lining called the mucosa. In the mouth, stomach, and small
intestine, the mucosa contains tiny glands that produce juices to help
digest food. In addition, there are two solid organs, the liver and pancreas,
involved in digestion. These organs produce digestive juices that reach
the intestine though small tubes. Parts of other organ systems such as
nerves and blood also play major roles in digestion. 