Blood Capillaries; their function and management
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Basic Information[edit | edit source]
| Veličina | Hodnota | Značka / Vzorec |
|---|---|---|
| Length | 750 μm | l |
| Diameter | 3 μm | r |
| Surface area | 14 000 μm2 | 2 × π × r × l |
| Surface area including venules involved in substance exchange | 25 000 μm2 | |
| Total number | 40 × 109 | |
| Total area | 1000 m2 |
The capillary wall is formed of an endothelial layer, the basement membrane, and isolated pericytes that wrap around endothelial cells. Pericytes can regulate the lumen of the blood vessel. At rest, only 25-35% of the capillaris are active. The capillaries are not evenly distributed throughout the body (from 300-400 per mm3 in transverse striated muscles to 2500 - 3000 per mm3 in the myocardium).
Substance and gas exchange occurs at the level of the capillaries. The degree of permeability is affected by the distribution of the endothelium . There are three different types of layouts:
- Continuous endothelium lining,
- Fenestrated endothelium – permeable to water and small hydrophilic molecules,
- Discontinuous endothelium – fully permeable to all plasma components
By filtering the plasma through the capillary wall, tissue fluid is formed.
Links[edit | edit source]
Related Articles[edit | edit source]
Reference[edit | edit source]
- TROJAN, Stanislav, et al. Lékařská fyziologie. 4., přeprac. a uprav vydání. Praha : Grada Publishing, a.s, 2003. 772 s. ISBN 80-247-0512-5.
- LÜLLMANN-RAUCH, Renate. Histologie. 1. vydání. Praha : Grada, 2012. 576 s. ISBN 978-80-247-3729-4.
