cell volume homeostasis

Definition

Target type: biologicalprocess

Any process involved in maintaining the steady state of a cell's volume. The cell's volume refers to the three-dimensional space occupied by a cell. [GOC:dph, GOC:go_curators, GOC:tb]

Cell volume homeostasis is a critical process that ensures cells maintain a stable internal volume despite fluctuations in the extracellular environment. This delicate balance is essential for normal cellular function and survival. Cells are constantly exchanging water and solutes with their surroundings, which can lead to changes in volume. To counteract these changes, cells employ a complex array of mechanisms that regulate the movement of water and solutes across their plasma membranes.

The key players in cell volume homeostasis are:

- **Aquaporins:** These transmembrane proteins facilitate the rapid movement of water across the cell membrane, acting as water channels. Their expression and activity are regulated by a variety of factors, including osmotic stress, hormones, and growth factors.

- **Ion pumps and transporters:** These proteins actively transport ions across the cell membrane, creating electrochemical gradients that drive the movement of water and other solutes. Examples include the sodium-potassium pump, which maintains the electrochemical gradient across the plasma membrane, and the sodium-hydrogen exchanger, which regulates intracellular pH.

- **Osmolytes:** These small organic molecules are accumulated or released by cells to adjust their osmotic pressure. Examples include amino acids, sugars, and polyols.

When cells are exposed to a hypotonic environment (lower solute concentration than the cell interior), water rushes into the cell, causing it to swell. To counteract this swelling, cells activate mechanisms that increase the efflux of water and solutes, such as:

- **Aquaporin activation:** Increases water permeability of the plasma membrane.

- **Ion pump activation:** Expels ions, such as sodium, potassium, and chloride, out of the cell.

- **Osmolyte release:** Cells release osmolytes, reducing intracellular osmotic pressure.

Conversely, in a hypertonic environment (higher solute concentration than the cell interior), water moves out of the cell, causing it to shrink. To counteract shrinkage, cells activate mechanisms that increase the influx of water and solutes, such as:

- **Aquaporin inhibition:** Decreases water permeability of the plasma membrane.

- **Ion pump activation:** Pumps ions, such as sodium, potassium, and chloride, into the cell.

- **Osmolyte accumulation:** Cells accumulate osmolytes, increasing intracellular osmotic pressure.

Disruptions in cell volume homeostasis can lead to a variety of cellular pathologies, including:

- **Cell swelling:** Can damage organelles and disrupt normal cellular function.

- **Cell shrinkage:** Can lead to cell death and tissue damage.

- **Water imbalance:** Can contribute to diseases such as edema and dehydration.

The intricate regulation of cell volume homeostasis is essential for maintaining normal cellular function and tissue integrity.'
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Proteins (13)

Compounds (86)