Question

Blood flow to the kidneys is typically 1,200 ml/min. Urine flow and glomerular filtration rates are 1.5 ml/min and 125 ml/min, respectively. [6 points] (a) What percentage of the blood entering the kidneys is filtered every minute? (b) What fraction of the total blood flow is filtered every minute? (c) About how long does it take to filter all the blood in the body if disease causes the glomerular filtration rate to decrease by a factor of two? What would be an adverse consequence of the lengthened filtration time?

Answer 1

Given that

Renal blood flow = 1200ml

Urine flow = 1.5ml/min

Glomerular filtrtae rate = 125ml

1) percentage of blood entering the kidney is filtered every minute = Glomerular filtrtae rate (ml/min)/ Renal blood flow(ml/min) *100

percentage of blood entering the kidney is filtered every minute = 125ml/min / 1200ml/min *100

                                                                                         = 125/12 = 10.4 %

2)Fraction of blood filtered every minute = GFR /Renal blood flow = 125/12000 = 0.1

3)When the GFR is decreased by a factor of 2

New GFR = old GFR - Old GFR /2 = 125- 125/2 = 62.5 Ml/min

Total volume of blood in the Body = 5Liters

62.5 ml is filtered by the kidney in on minute

so, the time taken to filtrate 5 liter will be = 5Liters/62.5ml = 5000ml/62.5 = 80minutes = 1 hour and 20minute

4)when the filtration time is prolonged, the amount of blood filtered per minute by the kidney (GFR ) will reduces.

So, that the metabolic waste in the blood cannot be filtered faster, it will produce somany metabolic diseases.

Blood levels of creatinine, ammonia , increases .THi swill eventually lead to kidney failure and patient need to be undergo dialysis