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Friday, November 9, 2012

About capillaries in the human body

About capillaries in the human body
Capillaries a channel very precise, like hair diameter ranges between 0.007 - 0.014 mm, ranging along the filament between 0.5 - 1 mm, and consists Jdraha of layer Mobiles one, numbering ten billion Rite, and length combined about 80 thousand kilometers. The combined area of ​​approximately 500 square meters
The key to the blood circulatory system, linking small arteries veins are small, and have permeability that facilitate the spread of nutrients and waste and gases between the blood in the capillaries and the fluid surrounding the cells of the body interstitial fluid
And an extensive network of pipelines is very narrow, allowing a narrow diameter of the blood flow and slow so that it can perform its function exchange of gases and nutrients.
Functions capillaries
Capillaries has the following functions:
- The exchange of gas exchange gases between the blood and tissues of the body- The exchange of nutrients nutrients and quotients metabolism between blood and body- Filter and purify the blood of toxins and waste wastes across whiskers gathered in college known as "kippah renal"- Create peripheral resistance to blood flow- Contribute to the preservation of the venous return and Hesel heart and arterial pressure
Blood pressure in the capillaries:
Blood pressure in the capillaries is not static, or similar, is on the arterial side about 40 mm Hg, and gradually reduce as we head toward the venous end becomes in the middle of 30 mm Hg, and decreased at the venous end of up to 15 mm Hg.
The pressure in the capillaries depends on case of arterioles nutrients, and veins, enlarging arterioles increases blood pressure in the capillaries, and contrast, the narrowing of veins related Balsairat raises blood pressure within Cgarat.
There are several factors that affect the pressure inside the capillaries:
- Neurological factors: Vatharh constrictor nerves bristles lead to higher pressure inside
- Chemical agents:
A - a hormone anti urinating A.D.H. Strait of filaments and thus raise blood pressure withinB - quotients metabolism such as carbon dioxide or histamine and acid milk telangiectasia فتخفض blood pressure withinT - adrenaline and Nord epinephrine Biqan relieved the pressure inside capillariesW - acetylcholine expanded filaments decreases pressure inside
- Factors mechanism:
A - Qatar arterioles: extend arterioles leads to the flow of a large amount of blood it were expandedB - venous pressure: increased pressure on the veins prevents the flow of blood from the capillaries, relieved the pressure in the capillariesT - gravity: reduce the pressure in the capillaries highest level of the heart, and raise the pressure in the capillaries below the level of the heart
- Physical factors:
A - warmth works on extended by low pressure insideB - cold working on Tadhagaha and pressure rises inside

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