It is important to understand that the small intestinal walls are made up of
circular folds (or villi) called plicae circulares. The mucosa folds itself into
these villi or microvilli to increase the absorption surface of the intestines.
These appear like ripples or waves that allow the body maximum potential for
digesting and absorbing its nutrition.
There are glands called Lieberkuhns at the base of many of the villi (in
the duodenum), which secrete digestive hormones and enzymes.
Jejunum
The second portion of the small intestine is approximately 8 feet long. The
duodenum and jejunum make up two-fifths of the small intestines. Digestive
enzymes from the duodenum are now acting upon most of the food particles.
Absorption of vital nutrients is now taking place as the digestive enzymes
break down the food particles to their simplest form.
Ileum
The third portion is approximately 15 to 30 feet long and comprises the lower
three-fifths of the small intestine. Most of the by-products of digestion now
have become amino acids (building blocks), monosaccharides (fuels), fatty
acids (oil and fuel), glycerol, vitamins and minerals. These are now being
absorbed or mixed with water to continue on their way out into the colon.
This liquid mixture now passes into the first part of the large bowel known as
the cecum, which is the first section of the ascending portion.
PANCREAS
The pancreas is both an endocrine gland and an exocrine gland and is located
in a horizontal position behind the stomach in front of the first and second
lumbar vertebrae. The head of the pancreas is attached to the duodenum
(small intestines) and the tail of the pancreas reaches to the spleen.
The body of the pancreas has many exocrine glands, which have their
own ducts all leading into the main pancreatic duct, which joins the common
bile duct. The common bile duct empties into the duodenum (the first portion
of the small intestines). All through the exocrine gland tissue are masses of