1. Physiology of microcirculation

3. microcirculation The microcirculation is a term used to describe the small vessels in the vasculature which are embedded within organs and are responsible for the distribution of blood within tissues; as opposed to larger vessels in the macrocirculation which transport blood to and from the organs. The vessels on the arterial side of the microcirculation are called the arterioles, which are well innervated, are surrounded by smooth muscle cells, and are 10-100 µm in diameter. Arterioles carry the blood to the capillaries, which are not innervated, have no smooth muscle, and are about 5-8 µm in diameter. Blood flows out of the capillaries into the venules, which have little smooth muscle and are 10-200 µm. The blood flows from venules into the veins. In addition to these blood vessels, the microcirculation also includes lymphatic capillaries and collecting ducts. The main functions of the microcirculation include the regulation of 1. blood flow and tissue perfusion 2. blood pressure, 3. tissue fluid (swelling or edema), 4. delivery of oxygen and other nutrients and removal of CO2 and other metabolic waste products, and 5. body temperature. The microcirculation also has an important role in inflammation.arteriolescapillariesvenulesblood pressurefluidbody temperature

4. microcirculation Most vessels of the microcirculation are lined by flattened cells, the endothelium and many are surrounded by contractile cells the smooth muscle or pericytes. The endothelium provides a smooth surface for the flow of blood and regulates the movement of water and dissolved materials in the plasma between the blood and the tissues. The endothelium also produce molecules that discourage the blood from clotting unless there is a leak. The smooth muscle cells can contract and decrease the size of the arterioles and thereby regulate blood flow and blood pressure.endotheliumsmooth musclepericytes

5. Transport of substances through capillary membrane Substances are transported through capillary membrane are lipid soluble as O2 or CO2 and water-soluble as ions or glucose. At arterial end of capillary pressure is higher than interstitial fluid pressure, which causes filtration. At venous end of capillary plasma colloid osmotic pressure is lower than interstitial pressure, which cause reabsorbtion.

6. Types of capillary 1. Somatic. 2. Visceral 3. Sinusoidal

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