Page 160 - The Cell in 40 Topics

ne feature of the stomach’s mucus is that it contributes to the
bone marrow that produces blood. It ensures that vitamin B ,
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which is of enormous importance to the body, reaches the
marrow. When we examine the journey that vitamin B undertakes before
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it reaches the marrow, and the role played by this in the stomach mucosa,
we shall see yet another miracle taking place at the microscopic level.
After entering the human body, vitamin B makes a long journey
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through the digestive system. It finally enters the bloodstream from the
small intestine and reaches the bone marrow cells (Figure 127).
The absorption of vitamin B takes place in the small intestine.
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However, no digestive cell in the small intestine is able to trap the vitamin.
There is a special group of cells in one small region of the small intestine
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that has solely been charged with capturing vitamin B . This group of
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cells dedicates their lives, in a most miraculous manner, to trapping this vi-
tamin. These cells identify and seize vitamin B from among trillions of
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molecules. How do these cells identify it, and how do they distinguish it
from so many other substances? Why do they feel themselves obliged to
capture vitamin B ?
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