WordNet

cause to flow; "The artist flowed the washes on the paper"
the amount of fluid that flows in a given time (同)flow_rate, rate of flow
any uninterrupted stream or discharge
cover or swamp with water
the act of flowing or streaming; continuous progression (同)stream
the motion characteristic of fluids (liquids or gases) (同)flowing
move or progress freely as if in a stream; "The crowd flowed out of the stadium" (同)flux
be abundantly present; "The champagne flowed at the wedding"
(physical chemistry) a fourth state of matter distinct from solid or liquid or gas and present in stars and fusion reactors; a gas becomes a plasma when it is heated until the atoms lose all their electrons, leaving a highly electrified collection of nuclei and free electrons; "particles in space exist in the form of a plasma"
a green slightly translucent variety of chalcedony used as a gemstone
the colorless watery fluid of the blood and lymph that contains no cells, but in which the blood cells (erythrocytes, leukocytes, and thrombocytes) are suspended (同)plasm, blood_plasma

PrepTutorEJDIC

《副詞巳句始を伴って》〈気体・液体・電気などが〉『流れる』 / 《副詞[句]を伴って》〈言葉・人々などず〉流れるように続く / 〈心・場所などが〉(…で)いっぱいになる,満ちあふれる《+『with』+『名』》 / 《副詞[句]を伴って》〈髪・服などが〉長く垂れる;風になびく / 〈潮が〉満ちる / (…から)生じる,発生する《+『from』+『名』》 / 〈C〉《単数形で》(気体・液体・電気などの)『流れ』《+『of』+『名』》 / 〈C〉《単数形で》(言葉・人などの)絶え間のない(よどみのない)流れ《+『of』+『名』》 / 〈C〉《単数形で》(…の)洪水,はんらん《+『of』+『名』》 / 〈U〉《the flow》満ち潮,上げ潮
(また『blood plasma』)血漿,リンパ漿 / 原形質
腎臓の
流れる / 流ちょうな / ゆるやにかに垂れた

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/26 08:38:21」(JST)

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Parameter	Value
renal blood flow	RBF=1000 ml/min
hematocrit	HCT=40%
renal plasma flow	RPF=600 ml/min
filtration fraction	FF=20%
glomerular filtration rate	GFR=120 ml/min
urine flow rate	V=1 mL/min

Sodium	Inulin	Creatinine	PAH
S_Na=150 mEq/L	S_In=1 mg/mL	S_Cr=0.01 mg/ml	S_PAH=
U_Na=710 mEq/L	U_In=150 mg/mL	U_Cr=1.25 mg/mL	U_PAH=
C_Na=5 mL/min	C_In=150 ml/min	C_Cr=125 mL/min	C_PAH=420 ml/min
			ER=90%
			ERPF=540 ml/min

Introduction

In the physiology of the kidney, renal blood flow (RBF) is the volume of blood delivered to the kidneys per unit time. In humans, the kidneys together receive roughly 22% of cardiac output, amounting to 1.1 L/min in a 70-kg adult male. RBF is closely related to renal plasma flow (RPF), which is the volume of blood plasma delivered to the kidneys per unit time.

While the terms generally apply to arterial blood delivered to the kidneys, both RBF and RPF can be used to quantify the volume of venous blood exiting the kidneys per unit time. In this context, the terms are commonly given subscripts to refer to arterial or venous blood or plasma flow, as in RBF_a, RBF_v, RPF_a, and RPF_v. Physiologically, however, the differences in these values are negligible so that arterial flow and venous flow are often assumed equal.

Renal plasma flow

Renal plasma flow is the volume of plasma that reaches the kidneys per unit time. Renal plasma flow is given by the Fick principle:

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:

where P_a is the arterial plasma concentration of the substance, P_v is its venous plasma concentration, U_x 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_a is assumed to be equal to RPF_v, thus

Rearranging yields the previous equation for RPF:

Measuring

Values of P_v are difficult to obtain in patients. In practice, PAH clearance is used instead to calculate the effective renal plasma flow (eRPF). PAH (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_v to zero in the equation for RPF yields

which is the equation for renal clearance. For PAH, this is commonly represented as

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:

Autoregulation and Renal Failure

If the kidney is methodologically per-fused at moderate pressures (90-220 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.^[1] Patients with poor renal perfusion caused by drugs that inhibit angiotensin-converting enzyme face Renal failure.^[2]

References

^ Ganong. Ganong's Review of Medical Physiology (24 ed.). TATA McGRAW HILL. p. 678. ISBN 978-1-25-902753-6.
^ Ganong. Ganong's Review of Medical Physiology (24 ed.). TATA McGRAW HILL. p. 678. ISBN 978-1-25-902753-6.

Bibliography

Boron, Walter F., Boulpaep, Emile L. (2005). Medical Physiology: A Cellular and Molecular Approach. Philadelphia, PA: Elsevier/Saunders. ISBN 1-4160-2328-3.
Eaton, Douglas C., Pooler, John P. (2004). Vander's Renal Physiology (8th edition ed.). Lange Medical Books/McGraw-Hill. ISBN 0-07-135728-9.

External links

Renal Clearance Techniques

UpToDate Contents

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1. Chapter 2D：GFRと腎血漿流量の調節 chapter 2d regulation of gfr and renal plasma flow
2. Chapter 2E：腎循環の臨床的評価 chapter 2e clinical evaluation of the renal circulation
3. Chapter 2A：糸球体の解剖学的構造および機能 chapter 2a glomerular anatomy and function
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