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Blood Pressure Physiology (view source)
Revision as of 10:32, 26 October 2010
, 10:32, 26 October 2010→Kidney and Fluid Balance Mechanisms
==Kidney and Fluid Balance Mechanisms==
==Kidney and Fluid Balance Mechanisms==
The kidneys help to regulate the blood pressure by increasing (when blood pressure falls) or decreasing (when blood pressure rises) the blood volume, and also by the renin-angiotensin system described above. The kidney-fluid system is the main method of the long-term control of blood pressure.
The kidneys help to regulate the blood pressure by increasing (when blood pressure falls) or decreasing (when blood pressure rises) the blood volume, and also by the renin-angiotensin system described above. The kidney-fluid system is the main method of the long-term control of blood pressure. In additiion to the RAAS sytem, renal blood flow is regulated by:
*Pressure Diuresis: As arteriolar blood pressure increases, so flow through the kidneys also increases and this increases filtration rate and urinary output
*Pressure Natriuresis: If renal perfusion pressure is increased then sodium excretion increases i.e. sodium excretion increases when blood pressure increases. If more sodium is excreted less water is reabsorbed therefore the ECF volume decreases and blood pressure decreases. The actual mechanism is not clear but it is thought to involve a direct effect of the pressure on the renal interstitium.
== Local Regulators of Blood Flow ==
== Local Regulators of Blood Flow ==