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A Lindbergh perfusion pump, c. 1935, an early device for simulating natural perfusion. Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, [1] usually referring to the delivery of blood to a capillary bed in tissue. Perfusion may also refer to fixation via perfusion, used in histological ...
The diffusion constant need to be updated to the relative diffusion constant between two diffusing molecules. This estimation is especially useful in studying the interaction between a small molecule and a larger molecule such as a protein. The effective diffusion constant is dominated by the smaller one whose diffusion constant can be used ...
The exchange of dissolved gases between the blood and tissues is controlled by perfusion and to a lesser extent by diffusion, particularly in heterogeneous tissues. The distribution of blood flow to the tissues is variable and subject to a variety of influences.
Diffusion is the first and most important mechanism that allows the flow of small molecules across capillaries. The process depends on the difference of gradients between the interstitium and blood, with molecules moving to low concentrated spaces from high concentrated ones. [8]
The concept of diffusion is widely used in many fields, including physics (particle diffusion), chemistry, biology, sociology, economics, statistics, data science, and finance (diffusion of people, ideas, data and price values). The central idea of diffusion, however, is common to all of these: a substance or collection undergoing diffusion ...
The assumption that perfusion is the limiting mechanism leads to a model comprising a group of tissues with varied rates of perfusion, but supplied by blood of approximately equivalent gas concentration. It is also assumed that there is no gas transfer between tissue compartments by diffusion.
Dispersive mass flux is analogous to diffusion, and it can also be described using Fick's first law: J = − E d c d x , {\displaystyle J=-E{\frac {dc}{dx}},} where c is mass concentration of the species being dispersed, E is the dispersion coefficient, and x is the position in the direction of the concentration gradient.
Forced diffusion occurs because of the action of some external force; Diffusion can be caused by temperature gradients (thermal diffusion) Diffusion can be caused by differences in chemical potential; This can be compared to Fick's law of diffusion, for a species A in a binary mixture consisting of A and B: