Special Control Mechanisms

Nutrients have to cross from the arteries through the artery wall, in order to penetrate into the necessary tissues. Although the artery wall has very small pores, no substance can penetrate it by itself. It is the blood pressure that facilitates this penetration. However, nutrients crossing over into the tissues in larger quantities than necessary causes inflammation in the tissues. Therefore, there is a special mechanism instituted for balancing blood pressure and withdrawing fluid back to the blood. This is the responsibility of albumin, which is larger than the pores in the artery wall and numerous enough in the blood to suck up the water like a sponge. If there were no albumin in the body, it would swell like a dry bean left in water.

If a blood clot (left) forms in the coronary veins of the heart and continues to enlarge, it leads to a heart attack. In some situations due to blood pressure, heart tissue is ruptured. Blood gushes out of the heart as if spraying from a hose (right).

On the contrary, materials in the blood should not enter the tissues of the brain uncontrolled, since unwanted substances can severely damage nerve cells (neurons). Therefore, the brain is protected against all possible scenarios of harm. Dense cell layers close off pores. All substances are required to pass through these layers as if passing through a security checkpoint, which facilitates a balanced flow of nutrients into the most sensitive organ of the whole body.