Physiology
ANAESTHESIA AND INTENSIVE CARE MEDICINE 10:6 271 © 2009 Elsevier Ltd.
All rights reserved.
Renal blood flow,
glomerular filtration and
plasma clearance
John C Atherton
Abstract
Homeostatic and excretory functions of the kidney depend on blood...
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Physiology
ANAESTHESIA AND INTENSIVE CARE MEDICINE 10:6 271 © 2009 Elsevier Ltd.
All rights reserved.
Renal blood flow,
glomerular filtration and
plasma clearance
John C Atherton
Abstract
Homeostatic and excretory functions of the kidney depend on blood flow
(~25% cardiac output) and glomerular ultrafiltration (~20% renal plasma
flow).
Blood flow distribution is not uniform, with only 10% reaching the
medulla.
Selectivity of ultrafiltration is related to molecular size, shape
and electrostatic charge of molecules, and structure of the glomerular
capillary barrier with its negatively charged glycoproteins.
Ultrafiltration,
determined by the balance between hydrostatic and colloid osmotic pressures (Starling forces) in the glomerular capillary and Bowman’s space,
occurs along the length of the capillary: hydrostatic pressure is relatively unchanged and always exceeds plasma colloid osmotic pressure
plus pressure in Bowman’s space.
Ultrafiltration is influenced by changes
in renal
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