Solvent drag

Solvent drag refers to the phenomenon where solutes are carried along with the flow of water across a semi-permeable membrane. This process is particularly significant in the physiology of the kidney and the intestine.

Overview

Solvent drag occurs when water moves across a semi-permeable membrane, carrying with it dissolved substances. This process is driven by osmotic pressure and is a key mechanism in the absorption and secretion of fluids in the body.

In the kidney, solvent drag contributes to the reabsorption of sodium and chloride ions in the proximal tubule. Similarly, in the intestine, solvent drag is responsible for the absorption of nutrients and electrolytes.

Mechanism

The mechanism of solvent drag involves the movement of water across a semi-permeable membrane due to osmotic pressure. This movement of water carries with it dissolved substances, such as ions and nutrients.

In the kidney, the osmotic pressure is created by the active transport of sodium ions out of the proximal tubule cells into the interstitial fluid. This creates a concentration gradient that drives the movement of water, along with other solutes, out of the tubule and into the interstitial fluid.

In the intestine, the osmotic pressure is created by the active transport of nutrients and electrolytes into the intestinal cells. This creates a concentration gradient that drives the movement of water, along with other solutes, into the cells and then into the bloodstream.

Clinical significance

Solvent drag plays a crucial role in the body's ability to maintain homeostasis. Any disruption in this process can lead to a variety of health issues, including dehydration, electrolyte imbalance, and kidney disease.

For example, in conditions such as diarrhea, the rapid movement of water out of the body can lead to dehydration and electrolyte imbalance. Similarly, in kidney disease, the impaired reabsorption of solutes can lead to an accumulation of waste products in the blood.

See also

• Osmosis
• Active transport
• Passive transport
• Kidney function
• Intestinal absorption

References

Solvent drag Resources
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