Mass flow (life sciences)
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In the
blood circulation and transport of water
in vascular plant tissues. Mass flow is not to be confused with diffusion which depends on concentration gradients within a medium rather than pressure gradients of the medium itself.
Plant biology
In general, bulk flow in plant biology typically refers to the movement of water from the soil up through the plant to the leaf tissue through xylem, but can also be applied to the transport of larger solutes (e.g. sucrose) through the phloem.
Xylem
According to
hydrogen bonding combined with the high water pressure of the plant's substrate and low pressure of the extreme tissues (usually leaves).[2]
As in blood circulation in animals,
which?] do, however, have physiological mechanisms to reestablish the capillary action within their cells [clarification needed][citation needed
].
Phloem
Solute flow is driven by a difference in hydraulic pressure created from the unloading of solutes in the sink tissues.[4] That is, as solutes are off-loaded into sink cells (by active or passive transport), the density of the phloem liquid decreases locally, creating a pressure gradient.
See also
- Countercurrent exchange
- Pounds Per Hour
- Fluid Dynamics
- Mass flow rate
- Hemorheology
- Flying and gliding animals
References
- ^ Moyes & Schulte (2008). Principles of Animal Physiology. Pearson Benjamin Cummings. San Francisco, California
- ISBN 978-1605353531.
- ^ Pockman, W.T., Sperry, J.S., & O'Leary, J.W. 1995. Sustained and significant negative water pressure in xylem. 'Nature' 378: 715-716
- ISBN 978-0-387-78341-3.