Small is not only beautiful but also essential to life! We take food to supply nutrition to our body. How and from where this nutrition is received by the tissue cells of our body? Do you know? We all know that our heart pumps blood from the body organs to the lungs, and then returns the purified blood back to the body organs. But there is also a microcirculation existing at a microlevel between arteries, arterioles and the venules, veins! The components of this circulation are the Capillaries. Only through the walls of these capillaries, the nutrition is received by the tissue cells!
Section of a capillary tube
These capillary tubes do not empty their blood contents directly into the tissue cells. Then how does this wonderful transfer of nutrition take place? Large nutritive particles present in the blood of the capillary move through the cells of the capillary wall (called endothelial cells) onto the interstitial fluid found between the capillary and the tissue cells! From there they move on into the tissue cells! Smaller nutritive particles, gases like Oxygen, water and ions move to the interstitial fluid through the space present between the capillary wall cells! Likewise, waste products, like Carbon-di-oxide from tissue cells move into the capillary blood passing through the interstitial fluid and then through the capillary wall.
These capillaries are also newly formed at the sites of a wounds to supply nutrition to the newly forming cells in the process of wound repair and healing! You shall find that only less capillaries are formed in the heart of persons having Cardiovascular risk factors like smoking, and also in those already having Coronary Heart Disease!
This ultimate wonder network of these capillaries is thus really essential for maintaining the human life! Even the brain gets nutrition from the special capillary networks! That means that every function of our body is dependent on it!
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