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  2. Mass flow (life sciences) - Wikipedia

    en.wikipedia.org/wiki/Mass_flow_(life_sciences)

    In the life sciences, mass flow, also known as mass transfer and bulk flow, is the movement of fluids down a pressure or temperature gradient. [1] As such, mass flow is a subject of study in both fluid dynamics and biology. Examples of mass flow include blood circulation and transport of water in vascular plant tissues. Mass flow is not to be ...

  3. Pressure flow hypothesis - Wikipedia

    en.wikipedia.org/wiki/Pressure_Flow_Hypothesis

    According to the hypothesis, the high concentration of organic substances, particularly sugar, inside the phloem at a source such as a leaf creates a diffusion gradient (osmotic gradient) that draws water into the cells from the adjacent xylem. This creates turgor pressure, also called hydrostatic pressure, in the phloem. The hypothesis states ...

  4. Pressure gradient - Wikipedia

    en.wikipedia.org/wiki/Pressure_gradient

    The horizontal pressure gradient is a two-dimensional vector resulting from the projection of the pressure gradient onto a local horizontal plane. Near the Earth's surface, this horizontal pressure gradient force is directed from higher toward lower pressure. Its particular orientation at any one time and place depends strongly on the weather ...

  5. Venous return - Wikipedia

    en.wikipedia.org/wiki/Venous_return

    Venous return curves showing the normal curve when the mean systemic filling pressure (Psf) is 7 mm Hg and the effect of altering the Psf to 3.5, 7, or 14 mm Hg. Hemodynamically, venous return (VR) to the heart from the venous vascular beds is determined by a pressure gradient (venous pressure - right atrial pressure) and venous resistance (RV ...

  6. Tonicity - Wikipedia

    en.wikipedia.org/wiki/Tonicity

    In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane-impermeable solutes across a cell membrane which determine the direction and extent of osmotic flux .

  7. Pulsatile flow - Wikipedia

    en.wikipedia.org/wiki/Pulsatile_flow

    is the angular frequency of the first harmonic of a Fourier series of an oscillatory pressure gradient, n: are the natural numbers, P' n: is the pressure gradient magnitude for the frequency nω, ρ: is the fluid density, μ: is the dynamic viscosity, R: is the pipe radius, J 0 (·) is the Bessel function of first kind and order zero, i: is the ...

  8. Transpulmonary pressure - Wikipedia

    en.wikipedia.org/wiki/Transpulmonary_pressure

    Transpulmonary pressure is the difference between the alveolar pressure and the intrapleural pressure in the pleural cavity. During human ventilation, air flows because of pressure gradients. P tp = P alv – P ip. Where P tp is transpulmonary pressure, P alv is alveolar pressure, and P ip is intrapleural pressure.

  9. Turgor pressure - Wikipedia

    en.wikipedia.org/wiki/Turgor_pressure

    Turgor pressure within the stomata regulates when the stomata can open and close, which plays a role in transpiration rates of the plant. This is also important because this function regulates water loss within the plant. Lower turgor pressure can mean that the cell has a low water concentration and closing the stomata would help to preserve water.