View source for Compliance (physiology)

{{About|the physiological term|other uses|Compliance (disambiguation)}}
{{mergefrom|Pulmonary compliance|discuss=Talk:Compliance (physiology)#Merger proposal|date=May 2008}}

'''Compliance''' is a [[Measurement|measure]] of the tendency of a hollow [[organ (anatomy)|organ]] to resist [[recoil]] toward its original [[dimensions]] upon removal of a distending or compressing force. It is the [[Multiplicative inverse|reciprocal]] of "elastance".

==Blood vessels==
The terms elastance and compliance are of particular significance in [[cardiovascular physiology]] and [[respiratory physiology]]. Increase in volume in response to increase in pressure. Specifically, the increase in blood volume in a vessel when the pressure in that vessel is increased. The tendency of the [[arteries]] and [[veins]] to stretch in response to pressure has a large effect on perfusion and blood pressure.<ref>{{GeorgiaPhysiology|3/3ch7/s3ch7_10}}</ref> 
Venous compliance is 20-24 times larger than arterial compliance.
Compliance is calculated using the following equation, where ΔV is the change in volume, and ΔP is the change in pressure:<ref>[http://www.cvphysiology.com/Blood%20Pressure/BP004.htm Vascular compliance<!-- Bot generated title -->]</ref>
:<math>C =  \frac{ \Delta V}{ \Delta P} </math>

Physiologic compliance is generally in agreement with the above and adds [[dP/dt]] as a common academic physiologic measurement of both pulmonary and cardiac tissues. Mathematical adaptation of utility formulas once best applied to [[rubber]] and [[latex]] now allow measurement of complex and dynamic physiologic states, specifically addressed here in pulmonary and cardiac tissue compliance. 

[[Vulcanization]] of natural rubber occurs when elements such as sulfur are introduced to the media. In industry, sulfur or similar additions are titrated to the desired compliance performance definition of the media. The [[Myocardium]] is decidedly not made of rubber but certainly shares many characteristics regarding infiltration by other agents. Introduction of [[Calcium]] within myocardial mass is a similar process that detracts from compliance and heralds [[Diastolic Dysfunction]].
 
Current proponents of restoration of [[Ventricular Dyssynchrony]] purport that cardiac dP/dt curves can be reversed, thus demonstrating clinical improvement. One could then assume that inexpensive echocardiographically defined reversal of derived E:A time intervals of flow across the mitral valve would follow these curves in support of the theory espoused.   
   
Veins have a much higher compliance than arteries (largely due to their thinner walls.) Veins which are abnormally compliant can be associated with [[edema]]. [[Compression stockings|Pressure stockings]] are sometimes used to externally reduce compliance, and thus keep blood from pooling in the legs.

The higher the compliance the more elastic the material, therefore steel has a lower compliance than a blood vessel.

==See also==
* [[Pulmonary compliance]]
* [[Windkessel effect]]

==References==
<references/>

==External links==
* {{MeshName|Compliance}}

{{Cardiovascular physiology}}
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[[Category:Respiratory physiology]]
[[Category:Physiology]]
[[Category:Cardiovascular system]]

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