Solvent drag, also known as bulk transport, is a phenomenon primarily in renal physiology

Renal physiology

Renal physiology is the study of the physiology of the kidney. This encompasses all functions of the kidney, including reabsorption of glucose, amino acids, and other small molecules; regulation of sodium, potassium, and other electrolytes; regulation of fluid balance and blood pressure;...

, but it also occurs in gastrointestinal physiology. It is when solute

Solution

In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...

s in the ultrafiltrate are transported back from the renal tubule by the flow of water rather than specifically by ion pumps or other membrane transport proteins.

It generally occurs in the paracellular, rather than transcellular, pathway across the tubular cells.

It is seen e.g. in the passive transport in renal sodium reabsorption

Renal sodium reabsorption

Renal reabsorption of sodium is a part of renal physiology. It uses Na-H antiport, Na-glucose symport, sodium ion channels . It is stimulated by angiotensin II and aldosterone, and inhibited by atrial natriuretic peptide....

, renal chloride reabsorption

Renal chloride reabsorption

Renal reabsorption of chloride is a part of renal physiology, in order not to lose too much chloride in the urine.-Overview table:...

 as well as renal urea handling

Renal urea handling

Renal urea handling is the part of renal physiology that deals with the reabsorption and secretion of urea. Movement of large amounts of urea across cell membranes is made possible by urea transporter proteins....

.