查看“︁腎血流量”︁的源代码

'''腎血流量'''（{{lang-en|Renal blood flow}}，[[縮寫]]：'''RBF'''），在[[腎]]的[[腎生理學|生理學]]，是表示每單位時間輸送到腎臟的血液體積。在人類中，腎臟一起接受大約[[心輸出量]](cardiac output)的22％，在一位70公斤的成年男性達<1.1升/分鐘>。RBF是和'''腎血漿流量'''(RPF)密切相關，即表示每單位時間輸送到腎臟的血漿體積。

雖然腎血流量這個術語通常適用於[[动脉]]血液遞送到腎臟，RBF及RPF可用於量化的每單位時間流出腎臟的[[靜脈]]血液體積。在這樣的背景下，這些術語通常賦予標誌來表示動脈或靜脈的血液或血漿的流動，如在RBF<sub>a</sub>、 RBF<sub>v</sub>、RPF<sub>a</sub>，及RPF<sub>v</sub>。然而在生理上、這些值的差異是可以忽略的，使得動脈血流及靜脈血流通常假定是相等的。

==腎血漿流量==
腎血漿流量是每單位時間到達的腎臟的[[血浆]]體積。腎血漿流量由下列的[[菲克原理]](Fick principle)表示出：

:<math>RPF = \frac{U_x V}{P_a - P_v}</math>
<!--
This is essentially a [[conservation of mass]] equation which balances the renal inputs (the [[renal artery]]) and the renal outputs (the [[renal vein]] and [[ureter]]). Put simply, a non-metabolizable solute entering the kidney via the renal artery has two points of exit, the renal vein and the ureter. The mass entering through the artery per unit time must equal the mass exiting through the vein and ureter per unit time:-->

:<math>RPF_a \times P_a = RPF_v \times P_v + U_x \times V</math>
<!--
where ''P<sub>a</sub>'' is the arterial plasma concentration of the substance, ''P<sub>v</sub>'' is its venous plasma concentration, ''U<sub>x</sub>'' is its [[urine]] concentration, and ''V'' is the urine flow rate. The product of flow and concentration gives mass per unit time.

As mentioned previously, the difference between arterial and venous blood flow is negligible, so ''RPF<sub>a</sub>'' is assumed to be equal to ''RPF<sub>v</sub>'', thus-->

:<math>RPF \times P_a = RPF \times P_v + U_x V</math>

<!--Rearranging yields the previous equation for RPF:-->

:<math>RPF = \frac{U_x V}{P_a - P_v}</math>

==量測==
{{main|PAH清除率}}

''P<sub>v</sub>''值很難從病患中獲得。<!--In practice, [[PAH clearance]] is used instead to calculate the [[effective renal plasma flow]] (eRPF). PAH ([[para-aminohippurate|''para''-aminohippurate]]) is freely filtered and it is not reabsorbed within the nephron. Although freely filtered not all PAH crosses into the primary urine within Bowman's capsule. PAH remaining in the vasa recta or peritubular capillaries is taken up actively by epithelial cells of the proximal convoluted tubule and secreted into the tubular lumen. In this way PAH, at low doses, is completely cleared from the blood during a single pass through the kidney. Accordingly, the venous plasma concentration of PAH is approximately zero. Setting ''P<sub>v</sub>'' to zero in the equation for RPF yields-->

:<math>eRPF = \frac{U_x}{P_a} V</math>
<!--
which is the equation for [[renal clearance]]. For PAH, this is commonly represented as-->

:<math>eRPF = \frac{U_{PAH}}{P_{PAH}} V</math>
<!--
Since the venous plasma concentration of PAH is not exactly zero (in fact, it is usually 10% of the PAH arterial plasma concentration), eRPF usually underestimates RPF by approximately 10%. This margin of error is generally acceptable considering the ease with which PAH infusion allows eRPF to be measured.

Finally, renal blood flow (RBF) can be calculated from a patient's RPF and [[hematocrit]] using the following equation:-->

:<math>RBF = \frac{RPF}{1-Hct} </math>

==自動調節及腎衰竭==<!--
If the kidney is methodologically per-fused at moderate pressures (90–220&nbsp;mm Hg performed on an experimental animal; in this case, a dog), then, there is a proportionate increase of:
 -Renal Vascular Resistance
Along with the increase in pressure.
At low perfusion pressures, [[Angiotensin]] II may act by constricting the efferent arterioles, thus mainlining the GFR and playing a role in autoregulation of Renal Blood Flow.<ref>{{cite book|last1=Ganong|title=Ganong's Review of Medical Physiology|date=2012-01-01|url=https://archive.org/details/ganongsmedicalph0000barr|publisher=TATA McGRAW HILL|isbn=978-1-25-902753-6|pages=[https://archive.org/details/ganongsmedicalph0000barr/page/678 678]|edition=24}}</ref>
Patients with poor renal perfusion caused by drugs that inhibit angiotensin-converting enzyme face [[Renal failure]].<ref>{{cite book|last1=Ganong|title=Ganong's Review of Medical Physiology|date=2012-01-01|url=https://archive.org/details/ganongsmedicalph0000barr|publisher=TATA McGRAW HILL|isbn=978-1-25-902753-6|pages=[https://archive.org/details/ganongsmedicalph0000barr/page/678 678]|edition=24}}</ref>
-->
==參考文獻==
{{refbegin}}
* {{cite book | author=Boron, Walter F., Boulpaep, Emile L. | year=2005 | title=Medical Physiology: A Cellular and Molecular Approach | url=https://archive.org/details/medicalphysiolog0000boro | publisher=Elsevier/Saunders | location=Philadelphia, PA | isbn=1-4160-2328-3}}
* {{cite book | author=Eaton, Douglas C., Pooler, John P. | year=2004 | title=Vander's Renal Physiology | url=https://archive.org/details/vandersrenalphys0000eato | edition=8th edition | publisher=Lange Medical Books/McGraw-Hill | isbn=0-07-135728-9}}
{{refend}}

==外部連結==
* [https://web.archive.org/web/20131224113404/http://web.squ.edu.om/med-Lib/MED_CD/E_CDs/anesthesia/site/content/v02/020586r00.htm Renal Clearance Techniques]

{{renal physiology}}

{{DEFAULTSORT:Renal Blood Flow}}
[[Category:肾脏生理学]]