Search results
Results From The WOW.Com Content Network
A capillary is a small blood vessel, from 5 to 10 micrometres in diameter, and is part of the microcirculation system. Capillaries are microvessels and the smallest blood vessels in the body. They are composed of only the tunica intima (the innermost layer of an artery or vein), consisting of a thin wall of simple squamous endothelial cells. [2]
x is the thickness of the barrier; Different types of capillaries allow the diffusion of different molecules. The surface charge of endothelial cells at points of diffusivity can determine which type of molecule can diffuse through the capillary walls. If the surface is hydrophilic, it will allow water and charged molecules to pass through.
It ranges from a diameter of about 30–25 millimeters for the aorta [24] to only about 5 micrometers (0,005 mm) for the capillaries. [25] Vasoconstriction is the constriction of blood vessels (narrowing, becoming smaller in cross-sectional area) by contracting the vascular smooth muscle in the vessel walls.
Lymph capillaries or lymphatic capillaries are tiny, thin-walled microvessels located in the spaces between cells (except in the central nervous system and non-vascular tissues) which serve to drain and process extracellular fluid. Upon entering the lumen of a lymphatic capillary, the collected fluid is known as lymph.
The capillary length can then be worked out the same way except that the thickness of the film, must be taken into account as the bubble has a hollow center, unlike the droplet which is a solid. Instead of thinking of a droplet where each side is λ c {\displaystyle \lambda _{c}} as in the above derivation, for a bubble m {\displaystyle m} is now
In particular, static capillary surfaces with gravity absent have constant mean curvature, so that a minimal surface is a special case of static capillary surface. They are also of practical interest for fluid management in space (or other environments free of body forces ), where both flow and static configuration are often dominated by ...
The converse argument is that generally artery walls are thicker and more muscular than veins as the blood passing through is of a higher pressure. This means that it would take longer for any oxygen to diffuse through to the cells in the tunica adventitia and the tunica media, causing them to need a more extensive vasa vasorum.
Blood exits the glomerular capillaries by an efferent arteriole instead of a venule, as is seen in the majority of capillary systems (Fig. 4). [ 3 ] This provides tighter control over the blood flow through the glomerulus, since arterioles dilate and constrict more readily than venules, owing to their thick circular smooth muscle layer ( tunica ...