Determinants of gfr
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Determinants of GFR. GFR = Capillary filtration coefficient X Net filtration pressure. Increased glomerular Capillary filtration coefficient increases GFR. Probably not a primary mechanism for day-to-day regulation of GFR.

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Determinants of GFR

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Determinants of gfr

Determinants of GFR

  • GFR = Capillary filtration coefficient X Net filtration pressure.

  • Increased glomerular Capillary filtration coefficient increases GFR.

    • Probably not a primary mechanism for day-to-day regulation of GFR.

    • Glomerular Capillary filtration coefficient is changed in some disease states such as diabetes millitus.


Determinants of gfr1

Determinants of GFR

  • GFR = Capillary filtration coefficient X Net filtration pressure.

  • Increased hydrostatic pressure in Bowman’s capsule decreases GFR (inverse is also true).

    • Normally, not a primary mechanism for day-to-day regulation of GFR.

    • Hydrostatic pressure in Bowman’s capsule can change in some pathologic conditions such as obstruction of the urinary tract.

Guyton’s Textbook of Medical Physiology 26-12


Determinants of gfr2

Determinants of GFR

  • GFR = Capillary filtration coefficient X Net filtration pressure.

  • Increased glomerular capillary colloid osmotic pressure decreases GFR.

    • Two factors regulate glomerular capillary colloid osmotic pressure:

      • Arterial plasma colloid osmotic pressure.

      • Filtration fraction.

Guyton’s Textbook of Medical Physiology 26-12 & 13


Determinants of gfr3

Determinants of GFR

  • Increased glomerular capillary colloid osmotic pressure decreases GFR (cont.)

    • Filtration fraction = GFR/renal blood flow

    • Such that, a lower rate of blood flow into the glomerulus causes an increase in the filtration fraction

      • decreased plasma volume with constant filtration volume increasing the protein concentration.

      • results in an increase in Glomerular colloid osmotic pressure which tends to decrease GFR.

        • inverse is also true.


Determinants of gfr4

Determinants of GFR

  • GFR = Capillary filtration coefficient X Net filtration pressure.

  • Increased glomerular capillary hydrostatic pressure increases GFR.

    • Three variables determine the glomerular hydrostatic pressure.

  • Arterial pressure.

  • Afferent arterial resistance.

  • Efferent arterial resistance.

Guyton’s Textbook of Medical Physiology 26-12


Determinants of gfr5

Determinants of GFR

  • Increased arterial pressureincreases glomerular capillary hydrostatic pressure resulting in increased GFR.

Sherwood’s Human Physiology 14-10 & 14-11 5th Ed & 14-9 & 14-10 6th Ed


Determinants of gfr6

Determinants of GFR

  • Increased afferent arterial resistancedecreases blood flow to the glomerular capillary resulting in decreased glomerular capillary hydrostatic pressure and reduced GFR.

Sherwood’s Human Physiology 14-10 & 14-11 5th Ed & 14-9 & 14-10 6th Ed


Determinants of gfr7

Determinants of GFR

  • Decreased afferent arterial resistance(dilation) _increases_ glomerular capillary hydrostatic pressure and GFR.

Sherwood’s Human Physiology 14-10 & 14-11 5th Ed & 14-9 & 14-10 6th Ed


Determinants of gfr8

Determinants of GFR

  • Moderate increases in efferent arterial resistance(constriction) increase glomerular capillary hydrostatic pressure and slightly increases GFR.

Guyton’s Textbook of Medical Physiology 26-12


Determinants of gfr9

Determinants of GFR

  • A severe increase in efferent arterial resistance (constriction)increases glomerular capillary hydrostatic pressure, but also increases the colloid osmotic pressure (due to the decreased renal blood flow). This results in a net decrease in GFR.

Guyton’s Textbook of Medical Physiology 26-14


Renal blood flow

Renal blood flow

  • The Kidneys get ~22% of the cardiac output.

    • Greater than what is needed to supply kidneys with nutrients and remove waste products.

    • Great volume is necessary to supply enough plasma for high GFRs.

    • The renal cortex receives most of the blood.

    • The renal medulla receives only 1-2% of the blood.

  • Renal blood flow is determined by the pressure gradient across the renal vasculature divided by the total renal vascular resistance.


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