Self-regulating glomerular filtration rate to prevent changes in renal excretion

2021-04-30 10:18 PM

Special control mechanisms and changes in blood pressure still have significant effects on water and salt excretion; This is called multiple urinary pressure or sodium urinary pressure, and it is very important in regulating body fluids and blood pressure.

Although the kidney's auto-regulating mechanisms are not perfect, they prevent potentially large changes in glomerular filtration and renal excretion of water and solutes that would occur with changes. in blood pressure. One can understand the importance of self-regulating dosing by considering the relative magnitude of glomerular filtration, tubular reabsorption, and renal excretion and changes in renal excretion. is possible without automatic air conditioning.

Normally, the glomerular filtration rate is about 180 L / day and the tubular reabsorption is 178.5 L / day, leaving 1.5 L / day of the liquid to be excreted in the urine. In the absence of self-correction, a relatively small increase in blood pressure (100-125 mm Hg) will cause a similar 25 percent increase in glomerular filtration rate (from about 180-225 L / day). If the tubular reabsorption remains constant at 178.5 L / day, the urine flow will increase to 46.5 L / day (the difference between the glomerular filtration rate and tubular reabsorption) the total increase in the water. Primary is more than 30 times. Because the total volume of the plasma is only about 3 litres, such a change will rapidly deplete the volume of blood.

In fact, changes in arterial pressure often have more or less effect on urine volume for two reasons: (1) self-regulation of the kidneys preventing large changes in glomerular filtration rate than would otherwise occur. in addition, and (2) there are additional adaptive mechanisms in the renal tubules that increase their rate of reabsorption as the glomerular filtration rate increases, a phenomenon known as glomerular-tubular balance.

Even with special control mechanisms, changes in blood pressure have significant effects on water and salt excretion; This is called multiple urinary pressure or sodium urinary pressure, and it is very important in regulating body fluids and blood pressure.


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