Biological complexity: osmotic presdsure controls (Introduction)

by David Turell , Friday, November 03, 2023, 21:04 (176 days ago) @ David Turell

A new way to measure in cells:

https://phys.org/news/2023-11-visualize-osmotic-pressure-tissue.html

"In order to survive, organisms must control the pressure inside them, from the single-cell level to tissues and organs. Measuring these pressures in living cells and tissues in physiological conditions is a challenge.

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"When molecules dissolved in water are separated into different compartments, water has the tendency to flow from one compartment to another to equilibrate their concentrations, a process known as osmosis. If some molecules cannot cross the membrane that separates them, a pressure imbalance—osmotic pressure—builds up between compartments.

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"Our cells are constantly moving molecules in and out to prevent the pressure build-up from crushing them. To do so, they use molecular pumps that allow them to keep the pressure in check. This osmotic pressure affects many aspects of cells' lives and even sets their size.

"When cells team up to build our tissues and organs, they, too, face a pressure problem: Our vascular system, or organs such as the pancreas or liver, contain fluid-filled cavities known as lumens that are essential for their function. If cells fail to control osmotic pressure, these lumens may collapse or explode, with potentially catastrophic consequences for the organ.

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"For this pressure sensor, they introduced a water droplet into an oil droplet that permits water to flow through. When these "double-droplets" were exposed to salt solutions of different concentrations, water flowed in and out of the internal water droplet, changing its volume, until pressures were equilibrated. The researchers showed that the osmotic pressure can be measured by simply checking the droplet size. They then introduced these double-droplets into living cells and tissues using glass microcapillaries to reveal their osmotic pressure.

"'It turns out that cells in animal tissues have the same osmotic pressure as plant cells but, unlike plants, they must balance it constantly with their environment to avoid exploding, since they do not have rigid cell walls," Campàs said.

"With this simple concept, this ingenious method now allows scientists to "see" osmotic pressure in a wide range of settings. "We know that several physical processes affect the working of our bodies," Campàs said. "In particular, osmotic pressure is known to play a fundamental role in the building of organs during embryogenesis, and also in the maintenance of healthy adult organs. With this new technique, we now can study how osmotic pressure impacts all these processes directly in living tissues.'"

Comment: the first cells that existed must have had osmotic pressure controls. Only by d eseign.