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Vasoactivity can vary between persons because of genetic and epigenetic differences, and it can be impaired by pathosis and by age. This makes the topic of haemodynamic response (including vascular compliance and vascular resistance ) a matter of medical and pharmacologic complexity beyond mere hydraulic considerations (which are complex enough ...
In most contexts a mention of rate of fluid flow is likely to refer to the volumetric rate. In hydrometry, the volumetric flow rate is known as discharge. Volumetric flow rate should not be confused with volumetric flux, as defined by Darcy's law and represented by the symbol q, with units of m 3 /(m 2 ·s), that is, m·s −1.
In fluid dynamics, the Hagen–Poiseuille equation is a physical law that gives the pressure drop in a fluid flowing through a long cylindrical pipe. The assumptions of the equation are that the flow is laminar viscous and incompressible and the flow is through a constant circular cross-section that is substantially longer than its diameter.
Δp is the pressure difference between the two ends, L is the length of pipe, μ is the dynamic viscosity, Q is the volumetric flow rate, R is the pipe radius, A is the cross-sectional area of pipe. The equation does not hold close to the pipe entrance. [8]: 3 The equation fails in the limit of low viscosity, wide and/or short pipe.
The V/Q ratio can therefore be defined as the ratio of the amount of air reaching the alveoli per minute to the amount of blood reaching the alveoli per minute—a ratio of volumetric flow rates. These two variables, V and Q, constitute the main determinants of the blood oxygen (O 2 ) and carbon dioxide (CO 2 ) concentration.
In fluid dynamics, the volumetric flux is the rate of volume flow across a unit area (m 3 ·s −1 ·m −2), and has dimensions of distance/time (volume/(time*area)) - equivalent to mean velocity. The density of a particular property in a fluid's volume, multiplied with the volumetric flux of the fluid, thus defines the advective flux of that ...
In Fowler's original study, the anatomic dead space was 156 ± 28 mL (n=45 males) or 26% of their tidal volume. [4] Despite the flexibility of the trachea and smaller conducting airways, their overall volume (i.e. the anatomic dead space) changes little with bronchoconstriction or when breathing hard during exercise. [4] [6]
For a given lung volume, the transpulmonary pressure is equal and opposite to the elastic recoil pressure of the lung. The transpulmonary pressure vs volume curve of inhalation (usually plotted as volume as a function of pressure) is different from that of exhalation, the difference being described as hysteresis. Lung volume at any given ...