Page 136 - The Miracle of the Blood and Heart

THE MIRACLE OF THE
BLOOD AND HEART

pores, it still permits no substances to pass through it. The
main element enabling nutrients to enter the tissues is blood
pressure. Thanks to the force of blood pressure, nutrients are
able to reach the requisite locations. However, there is also the
possibility that the level of substances "pumped" to the tissues
by means of blood pressure will be greater than normal.
Excessive fluids in the tissues will lead to edema. In order to
prevent this, albumin enters the equation as a competitor to
blood pressure, pulling liquid back into the blood. Because of

its higher concentration of albumin, the blood absorbs water
just like a sponge. Were it not for albumin, the body would
swell up like a dry sponge left to soak in water.
In the brain, however, substances in the blood need to pass
through the vessel walls in a rather different way. The brain is
a very sensitive organ, and if the substances in the blood were

The brain is afforded Brain
very special protection. capillary
Substances in the blood
Endothelial
pass through the so- cells
called brain/blood barri-
Water, oxygen
er after being subjected
or glucose
to a special inspection.
The endothelial cells in
the capillary walls con- Astrocytes
stitute a literally impass-
able barrier. Substances Nerve
in the blood can reach cells
the brain cells in ques-
Cerebrospinal
tion only if they are able
fluid
to pass through it.
Blood flow

Harun
Yahya

134