Question

Which of the following defines the net filtration pressure (NFP)?
(a) $BCOP-\left( GHP+CHP \right) $
(b) $GHP-\left( BCOP+CHP \right) $
(c) $\left( BCOP+GHP \right) -CHP$
(d) $\left( GHP-CHP \right) +BCOP$

Answer 1

Hint: A net filtration pressure (NFP) arises from the sum of all the forces, both osmotic and hydrostatic. It is the total pressure which encourages filtration. NFP is equal to the force pushing minus the force resisting.

Complete step by step answer:
The pressure produced due to the presence of plasma protein is blood colloid osmotic pressure (BCOP). It is an osmotic force.
Net Filtration pressure $\left( NFP \right) = GHP-\left( BCOP+CHP \right) $
The pressure produced due to the presence of fluid in the capsule of Bowman is capsular hydrostatic pressure (CHP). It is a force that is hydrostatic.
The glomerular hydrostatic pressure (GHP) provided by narrow different arterioles is pressurized. It is a force that is hydrostatic.
NFP defines rates of filtration through the kidney.
When the hydrostatic pressure produced by the heart forces water and solutes through the filtration membrane, the filtrate is produced by the glomerulus. Glomerular filtration is a passive operation, as filtrate is not formed by cellular energy on the filtration membrane. It is directly proportional to increased permeability and NFP. NFP rises as permeability rises; NFP decreases as permeability decreases.
So, the correct answer is, ‘$GHP-\left( BCOP+CHP \right) $’.

Note: In maintaining osmotic pressure both in the glomerulus and systemically, the proper concentration of solutes in the blood is important. There are cases in which too much protein moves through the filtrate of the kidney through the filtration slits. This excess protein in the filtrate causes circulating plasma proteins to be deficient. Together, blood colloid osmotic pressure decreases, leading to a rise in the amount of urine that could lead to dehydration. As they increase in size or number, renal calculi (kidney stones) appear to decrease NFP because they block the outward flow of urine from the kidney and build back pressure in the renal tubules and collecting ducts. Capsular hydrostatic pressure (CHP) would be increased by the backpressure.