Question

Given that the average glomerular capillary pressure is about 55 mmHg, plasma oncotic pressure is about 28 mmHg, and hydrostatic pressure within Bowman’s space is 20 mmHg, ultrafiltrate oncotic pressure is 0 mmHg, the GFR is 120 mL/min and each kidney weighs 125 g, define a filtration coefficient and find its magnitude.

Answer 1

Answer:

6.856ml/min/mmHg

Explanation:

We define the coefficient of filteration as Kf, which is a measure between the product of hydraulic conductivity and the surface area of the glomeruar capillatries. We can write it as,

$Kf= \frac{GFR}{ \Omega}$

Where $\Omega$ is the Net filteration pressure,

Here we know as well that the Net filteration pressure is

$\Omega = \alpha-\beta-\rho+\epsilon$

Where

$\alpha =$ The hydrostatic pressure of capillaries

$\beta =$ The oncotic pressure in capillaries

$\rho =$The hydrostatic pressure in bowman capsue

$\epsilon =$The oncotic pressure of ultrafilterate.

$\Omega=55-28-20+0$

$\Omega=7$

$Kf=\frac{120}{7}$

Kf=17.14 ml/min/mmHg of filteration pressure

Each kidney weighs 125 gm so both weigh 250gms.

Expressing it for per 100 gm of kidney:

$Kf_{100}= (17.14 /250)*100\\Kf_{100}=6.856ml/min/mmHg$