THE ILEUM
The ileum is the final section of the small intestine in most higher vertebrates,
including mammals, reptiles, and birds. In fish, the divisions of the small intestine are
not as clear and the terms posterior intestine or distal intestine may be used instead
of ileum.
The ileum follows the duodenum and jejunum and is separated from the cecum by
the ileocecal valve (ICV). In humans, the ileum is about 2–4 m long, and the pH is
usually between 7 and 8 (neutral or slightly alkaline).
Differences between jejunum and ileum
There is no line of demarcation between the jejunum and the ileum. There are,
however, subtle differences between the two.
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The ileum has more fat inside the mesentery than the jejunum
The ileum has a mesenteric and an anti-mesenteric vascular supply, while the
jejunum has only a mesenteric vasculature
BILE
Liver in the upper abdomen secretes bile
a.
Liver detoxifies blood by removing poisonous substances , destroys old red blood
cells, converts Hb bilirubin (present in bile), produces bile , produces urea from amino
groups and ammonia
b.
Gall bladder stores bile
c.
Secreted into small intestine by bile duct
RESPONSIBILITY
The ileum is responsible for absorption of fats, and bile salts. The pores in the ileum are
slightly bigger than those in the jejunum and allow vitamin B12, vitamins dissolved in
fatty liquids, electrolytes, bile salts and water to soak through the walls and into the
blood stream.
Where the ileum joins the large intestine is a valve, called the ileocecal valve, which
prevents the back flow of materials into the small intestine. By the time material reaches
this point, it has a rather pasty consistency.
STRUCTURE OF THE ILEUM
The villi increase the surface area of the ileum for the absorption. The villi are finger like
projections into the lumen of the gut. The villi increase the available surface area by ten
times.
The crypts contain the secretory cells of intestinal secretion.
Mucosa is a mucus secreting membrane.
The circular and longitudinal muscles combine to create the contractions known as
peristalsis that maintains the movement of chyme along the alimentary canal.
The serosa is a tough outer membrane composed of collagen.
DIAGRAMS OF THE ILEUM