Question

The concentration of glucose in plasma is $100mg/100ml$, and the GFR is $125ml/\min .$ How much glucose is filtered per minute?

Answer 1

Hint: Glomerular filtration rate (GFR) represents the flow of plasma from the glomerulus into Bowman’s space over a specified period and is the chief measure of kidney function. Use this formula, Filtered load of a substance = plasma concentration x GFR of the substance to unravel this problem.

Complete answer:
Let's discuss and find the solution.
Glucose is an example of an actively reabsorbed substance that's not regulated by the kidneys. The conventional plasma concentration of glucose is $100mg$ of glucose for each $100ml$ of plasma. Because glucose is freely filterable at the glomerulus. Within the plasma it passes into capsular glomeruli at the identical concentration. Accordingly, $100mg$ of glucose arc present in every $100ml$ of plasma filtered. With $125ml$ of plasma normally being filtered each minute, average \[GFR\text{ }=\text{ }125\text{ }mL/min\] .glucose of $125mg$ pass into the membrane with this filtrate every minute. The amount of any substance filtered per minute. It referred to as its filtered load, are often calculated as follows:
A substance filtered load is = plasma concentration x GFR of the substance
$\therefore $ Filtered load of glucose = \[100\text{ }mg/100\text{ }mL\text{ }\times \text{ }125\text{ }mL/min\]
 $=125mg/\min $
Hence, \[125\text{ }ml\] of glucose is filtered per minute.
At a relentless GFR, the filtered load of glucose is directly proportional to the plasma glucose concentration. Doubling the plasma glucose concentration to\[200\text{ }mg/100\text{ }ml\] doubles the filtered load of glucose to\[250\text{ }mg/min\] , and so on.

Note: Alternative method: All of the glucose presents is filtered by glomerulus. Therefore all of the glucose that outreach glomerular in one minute with \[125\text{ }ml\] of plasma (as GFR is\[125ml/min\] ) is filtered that is to say \[100\text{ }ml\] of plasma contains \[100\text{ }mg\] of glucose. \[125\text{ }ml\] of plasma that's being filtered will contain \[125\text{ }mg\] of glucose. Hence, \[125\text{ }ml\] of glucose is filtered per minute.