Question

The pressure exerted by plasma protein and blood is 27 mmHg and 50 mmHg respectively. What will be the pressure favouring the glomerular filtration?

• A. 77 mmHg
• B. 23 mmHg
• C. 27 mmHg
• D. 32 mmHg

Answer 1

Answer: (B)

23 mmHg

• Blood flowing through the glomerular capillaries as well as the filtrate in Bowman's space exerts a hydrostatic pressure. As the blood pressure in the glomerulus goes up, this hydrostatic pressure in the glomerulus goes up as well. This favors an increase in the glomerular filtration rate because this pressure forces more blood to be filtered by the glomerulus per unit of time. But the pressure exerted by plasma proteins within the glomerulus (oncotic pressure) tries to hold water back in the glomerulus.
  
• Hence, pressure favoring glomerular filtration = pressure exerted by blood - pressure exerted by plasma protein
  = 50 mm Hg - 27 mm Hg = $23mmHg$