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Capillary action of water (polar) compared to mercury (non-polar), in each case with respect to a polar surface such as glass (≡Si–OH). Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of external forces like gravity.
Water potential is the potential energy of water per unit volume relative to pure water in reference conditions. Water potential quantifies the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure and matrix effects such as capillary action (which is caused by surface tension).
The decrease in surface tension increases the wettability of the capillary walls, making it easier for the fluid to flow through the capillary. Heat also effects the viscosity of a fluid inside a capillary. An increase in heat decreases the viscosity of the lumenal fluid. A good example of this action can be observed in the human body during ...
Diffusion through the capillary walls depends on the permeability of the endothelial cells forming the capillary walls, which may be continuous, discontinuous, and fenestrated. [4] The Starling equation describes the roles of hydrostatic and osmotic pressures (the so-called Starling forces ) in the movement of fluid across capillary endothelium .
Capillary rise or fall in a tube. Jurin's law , or capillary rise , is the simplest analysis of capillary action —the induced motion of liquids in small channels [ 1 ] —and states that the maximum height of a liquid in a capillary tube is inversely proportional to the tube's diameter .
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. Capillaries are microvessels and the smallest blood vessels in the body.
In equations, the symbol Q is sometimes used to represent perfusion when referring to cardiac output. However, this terminology can be a source of confusion since both cardiac output and the symbol Q refer to flow (volume per unit time, for example, L/min), whereas perfusion is measured as flow per unit tissue mass (mL/(min·g)). [citation needed]
The equation is derived for capillary flow in a cylindrical tube in the absence of a gravitational field, but is sufficiently accurate in many cases when the capillary force is still significantly greater than the gravitational force. In his paper from 1921 Washburn applies Poiseuille's Law for fluid motion in a circular tube.