WordNet

submit (a report, etc.) to someone in authority; "submit a bill to a legislative body"
the income or profit arising from such transactions as the sale of land or other property; "the average return was about 5%" (同)issue, take, takings, proceeds, yield, payoff
a coming to or returning home; "on his return from Australia we gave him a welcoming party" (同)homecoming
a reciprocal group action; "in return we gave them as good as we got" (同)paying back, getting even
(American football) the act of running back the ball after a kickoff or punt or interception or fumble
a tennis stroke that sends the ball back to the other player; "he won the point on a cross-court return"
the act of going back to a prior location; "they set out on their return to the base camp"
the occurrence of a change in direction back in the opposite direction (同)coming back
bring back to the point of departure (同)take_back, bring back
go or come back to place, condition, or activity where one has been before; "return to your native land"; "the professor returned to his teaching position after serving as Dean"
make a return; "return a kickback"
return in kind; "return a compliment"; "return her love"
return to a previous position; in mathematics; "The point returned to the interior of the figure"
of or contained in or performing the function of the veins; "venous inflammation"; "venous blood as contrasted with arterial blood"; "venous circulation"
tending to return to an earlier state (同)reverting
tending to be turned back (同)reversive

PrepTutorEJDIC

(…から元の場所・状態などに)『帰る』,戻る《+from+名+to+『名』》 / 再び起こる,再発する / (元の持ち主・場所・状態に)…‘を'『返す』,戻す《+『名』+『to』+『名』》 / (同じようなやり方で)(…に対して)…‘を'『お返しする』,…‘で'こたえる《+『名』+『for』+『名』》 / …‘を'公式に報告する,答申する / 〈利子・利益など〉‘を'生む,生ずる / (国会議員などに)…‘を'選出する / 《しばしば引用節を従えて》…‘と'言葉を返す,返答する / 〈C〉(…から…べ)『帰って来ること』,帰還《+『from』+『名』+『to』+『名』》 / 〈U〉〈C〉(…が)再び起ること(来ること);(病気の)再発《+『of』+『名』》 / 〈U〉(…を)戻すこと,(…の)返却《+『fo』+『名』》 / 〈U〉〈C〉(…に対する)返礼,返報《+『for』+『名』》 / 〈C〉公式の報告[書],答申,(所得の)申告 / 〈C〉《しばしば複数形で》収入;利潤 / 《英》(国会議員などの)選挙 / 《米》『帰りの』;《英》往復の(《米》round・trip)) / 返しの,返報の
静脈[血]の / 葉脈の多い

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/05/26 15:34:15」(JST)

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[Wiki en表示]

Venous return is the rate of blood flow back to the heart. It normally limits cardiac output.

Superposition of the cardiac function curve and venous return curve is used in one hemodynamic model.^[1]

Physiology

Venous return (VR) is the flow of blood back to the heart. Under steady-state conditions, venous return must equal cardiac output (Q)^[2] when averaged over time because the cardiovascular system is essentially a closed loop. Otherwise, blood would accumulate in either the systemic or pulmonary circulations. Although cardiac output and venous return are interdependent, each can be independently regulated.

The circulatory system is made up of two circulations (pulmonary and systemic) situated in series between the right ventricle (RV) and left ventricle (LV). Balance is achieved, in large part, by the Frank–Starling mechanism. For example, if systemic venous return is suddenly increased (e.g., changing from upright to supine position), right ventricular preload increases leading to an increase in stroke volume and pulmonary blood flow. The left ventricle experiences an increase in pulmonary venous return, which in turn increases left ventricular preload and stroke volume by the Frank–Starling mechanism. In this way, an increase in venous return can lead to a matched increase in cardiac output.

Hemodynamically, venous return (VR) to the heart from the venous vascular beds is determined by a pressure gradient (venous pressure - right atrial pressure) and venous resistance (RV). Therefore, increases in venous pressure or decreases in right atrial pressure or venous resistance will lead to an increase in venous return, except when changes are brought about altered body posture (see below). Although the above relationship is true for the hemodynamic factors that determine the flow of blood from the veins back to the heart, it is important not to lose sight of the fact that blood flow through the entire systemic circulation represents both the cardiac output and the venous return, which are equal in the steady-state because the circulatory system is closed. Therefore, one could just as well say that venous return is determined by the mean aortic pressure minus the mean right atrial pressure, divided by the resistance of the entire systemic circulation (i.e., the systemic vascular resistance).^[3]

It is often suggested that venous return dictates cardiac output, effected through the Frank Starling mechanism. However, as noted above it is clear that, equally, cardiac output must dictate venous return since over any period of time both must necessarily be equal. Similarly, the concept of mean systemic filling pressure, the hypothetical driving pressure for venous return, is difficult to localise and impossible to measure in the physiological state. Furthermore, the Ohmic formulation used to describe venous return ignores the critical venous parameter, capacitance. It is confusion about these terms that has led some physiologists to suggest that the emphasis on 'venous return' be turned instead to more measurable and direct influences on cardiac output such as end diastolic pressure and volume which can be causally related to cardiac output and through which the influences of volume status, venous capacitance, ventricular compliance and venodilating therapies can be understood.^[4]

Factors affecting venous return mechanism

Musculovenous pump: Rhythmical contraction of limb muscles as occurs during normal locomotory activity (walking, running, swimming) promotes venous return by the muscle pump mechanism.
Decreased venous capacitance: Sympathetic activation of veins decreases venous compliance, increases venomotor tone, increases central venous pressure and promotes venous return indirectly by augmenting cardiac output through the Frank-Starling mechanism, which increases the total blood flow through the circulatory system.
Respiratory pump: During inspiration, the intrathoracic pressure is negative (suction of air into the lungs), and abdominal pressure is positive (compression of abdominal organs by diaphragm). This makes a pressure gradient between the infra- and supradiaphragmatic parts of v. cava inferior, "pulling" the blood towards the right atrium and increasing venous return.
Vena cava compression: An increase in the resistance of the vena cava, as occurs when the thoracic vena cava becomes compressed during a Valsalva maneuver or during late pregnancy, decreases return.
Gravity: The effects of gravity on venous return seem paradoxical because when a person stands up, hydrostatic forces cause the right atrial pressure to decrease and the venous pressure in the dependent limbs to increase. This increases the pressure gradient for venous return from the dependent limbs to the right atrium; however, venous return actually decreases. The reason for this is when a person initially stands, cardiac output and arterial pressure decrease (because right atrial pressure falls). The flow through the entire systemic circulation falls because arterial pressure falls more than right atrial pressure; therefore the pressure gradient driving flow throughout the entire circulatory system is decreased.
Pumping action of the heart: During the cardiac cycle right atrial pressure changes alter central venous pressure (CVP), because there is no valve between the heart's atria and the large veins. CVP reflects right atrial pressure. Therefore right atrial pressure also alters venous return.

References

^ Brengelmann GL (March 2003). "A critical analysis of the view that right atrial pressure determines venous return". J. Appl. Physiol. 94 (3): 849–59. doi:10.1152/japplphysiol.00868.2002. PMID 12391065.
^ "Cardiac Basic Physiology".
^ Klabunde, Richard E. "Venous Return - Hemodynamics". Cardiovascular Physiology Concepts. Retrieved 8 March 2011.
^ Reddi; Carpenter (2005). J Appl Physiol 98 http://jap.physiology.org/cgi/content/full/98/1/356#BIBL |url= missing title (help). Cite uses deprecated parameters (help)

UpToDate Contents

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English Journal

The Effects of Phenylephrine on Cardiac Output and Venous Return Depend on the Position of the Heart on the Frank Starling Relationship.

Cannesson M, Jian Z, Chen G, Vu TQ, Hatib F.Source1University of California Irvine.
Journal of applied physiology (Bethesda, Md. : 1985).J Appl Physiol.2012 May 3. [Epub ahead of print]
Introduction: Phenylephrine is daily used during anesthesia for treating hypotension. However, the effects of phenylephrine on cardiac output (CO) are not clear. We hypothesized that the impact of phenylephrine on cardiac output is related to preload dependency. Methods: Eight pigs were studied at a
PMID 22556399

Effect of an acute consumption of a moderate amount of ethanol on plasma endocannabinoid levels in humans.

Feuerecker M, Hauer D, Gresset T, Lassas S, Kaufmann I, Vogeser M, Briegel J, Hornuss C, Choukèr A, Schelling G.SourceCorresponding author: matthias.feuerecker@med.uni-muenchen.de.
Alcohol and alcoholism (Oxford, Oxfordshire).Alcohol Alcohol.2012 May;47(3):226-32. Epub 2012 Jan 24.
AIMS: Animal experiments have shown that the endocannabinoid system (ECS) plays an important role in the regulation of ethanol intake. We investigated these effects in healthy volunteers who consumed a moderate amount of ethanol (red wine) and measured plasma levels of the endocannabinoids (ECs) ana
PMID 22278319

Japanese Journal

下腿の間欠的空気圧迫法が血液透析中の末梢循環および全身の循環動態に及ぼす影響

安藤誠,前島愛子,角田朋美,辻田知圭子,藤井佑希,福島正樹
日本透析医学会雑誌 = Journal of Japanese Society for Dialysis Therapy 44(7), 629-635, 2011-07-28
【目的】下肢の循環不全がひき起こす深部静脈血栓症の理学的予防法として用いられる間欠的空気圧迫法（IPC）は機械的圧迫により下肢からの静脈還流を増加させる．われわれは，下腿のIPCが血液透析（HD）中の末梢循環および全身の循環動態に及ぼす影響について検討した．【方法】末梢循環はパルスオキシメータの原理を応用した灌流指標（PI）を用いて下肢末梢で評価し，全身の循環動態は，連続的ヘマトクリット測定装置に …
NAID 10029407285

総肺静脈還流異常症(TAPVR) (特集これが大切! 1カ月以内の新生児疾患) -- (見落としてはならない重症疾患・対応に迷う疾患)

中西敏雄
小児科診療 74(4), 593-597, 2011-04
NAID 40018758348

Related Pictures

★リンクテーブル★

リンク元	「静脈還流」
拡張検索	「total anomalous pulmonary venous return」「totally anomalous pulmonary venous return」「partial anomalous pulmonary venous return」
関連記事	「return」「venous」

「静脈還流」

　　[★]

英: venous return

SP. 573
2007年後期生理学授業プリント

圧勾配 (2007年後期生理学授業プリント)

細静脈内：約10 mmHg
右心房　：0～-5 mmHg

促進因子 (SP.573)

胸腔、腹腔のポンプ作用 (=呼吸ポンプ)

胸膜腔は吸気時には大きく陰圧となり、下大静脈の内腔を拡張させる。腹部では横隔膜の下行および腹壁の張力により腹腔内圧が上昇し、下大静脈が圧迫される。下肢への血流は弁によって遮られるため静脈血は腹腔から胸腔に押し出される。呼気時には横隔膜が弛緩して胸膜腔が大気圧に近づく。腹腔の内圧は下がり、下肢からの血流が増加する。このように呼吸に伴う血流の促進作用を呼吸ポンプという。