Changes

The glomerular filtration rate or GFR is the amount of fluid filtered from the capillaries into the Bowmans capsule per unit time.  The GFR can be expressed as the following formula:

The glomerular filtration rate or GFR is the amount of fluid filtered from the capillaries into the Bowmans capsule per unit time.  The GFR can be expressed as the following formula:

'''GFR = K_f x net filtration pressure'''

<center><big>'''GFR = K_f x net filtration pressure'''</big></center>

   

   

K_f = the filtration coefficent

K_f = the filtration coefficent

K_f can furthermore be expressed by the following formula

K_f can furthermore be expressed by the following formula

'''K_f = membrane permeability x filtration area'''

<center><big>'''K_f = membrane permeability x filtration area'''</big></center>

The GFR is practically proportional to metabolic body mass.  Therefore the bigger the animal the greater the GFR.  

The GFR is practically proportional to metabolic body mass.  Therefore the bigger the animal the greater the GFR.  

'''The following formula helps us to understand GFR and how various factors affect it.  Whilst reading this article you may find it useful to refer back to it:'''

'''The following formula helps us to understand GFR and how various factors affect it.  Whilst reading this article you may find it useful to refer back to it:'''

  <big>'''Q = (PA - PE) &#247; R'''</big>

<center><big>'''Q = (PA - PE) &#247; R'''</big></center>

  '''Q''' = Flow, '''PA''' = Pressure in afferent arteriole, '''PE''' = Pressure in efferent arteriole, '''R''' = Resistance

'''Q''' = Flow, '''PA''' = Pressure in afferent arteriole, '''PE''' = Pressure in efferent arteriole, '''R''' = Resistance

There are two major forces opposing GFR.  These are the hydrostatic pressure in the Bowmans space and the plasma protein osmotic pressure.  These are not under physiological control. The filtration coefficient is also beyond the realms of physiological control.  On the other hand the hydrostatic pressure in the capillaries and the renal blood flow are under physiological regulation and adjust filtration according to the bodies needs.   

There are two major forces opposing GFR.  These are the hydrostatic pressure in the Bowmans space and the plasma protein osmotic pressure.  These are not under physiological control. The filtration coefficient is also beyond the realms of physiological control.  On the other hand the hydrostatic pressure in the capillaries and the renal blood flow are under physiological regulation and adjust filtration according to the bodies needs.