Integration and control of circulatory function. Int Rev Physiol 1976;9:341-85
Date
01/01/1976Pubmed ID
135739Scopus ID
2-s2.0-0017278155 (requires institutional sign-in at Scopus site) 46 CitationsAbstract
In this chapter we have emphasized especially the intrinsic controls of the circulation, such as the autoregulation mechanism for control of local blood flow, automatic control of cardiac output, long-term control of arterial pressure, long-term control of blood volume, and automatic distribution of fluids between the circulation and the interstitial spaces. The reasons for emphasizing these mechanisms are several: first, many experiments have now shown that the intrinsic mechanisms can provide highly stable long-term control of the circulation. Second, the value of the nervous and hormonal controls have probably been greatly overemphasized in the past. And, third, there are special complexities of the intrinsic controls--such as nonlinearities, delay in responses, and other effects--that have made these difficult to understand; it is probably these difficulties that have led to their underemphasis. However, we have not meant to take from the nervous and hormonal systems their true importance in circulatory control. For instance, intrinsic mechanisms have almost no capability for acute arterial pressure control (only for long-term control), and they have no mechanism for providing the drive necessary to make the animal ingest water and electrolytes. These require the nervous controls. Also, nervous reflexes are important in enhancing the effectiveness of blood volume control and control of cardiac pumping. Among the hormonal mechanisms, the renin-angiotensin system can provide a modest degree of arterial pressure control when the pressure falls below normal by eliciting a vasoconstrictor response in the peripheral blood vessels. However, this system seems to have an even more important renal function, a direct effect on kidneys to cause fluid retention; this in turn increases the body fluid volume and in this way increases the arterial pressure. Finally, the roles of ADH and aldosterone in the control of blood volume have probably been greatly overemphasized. On the other hand, both clinical experience and experimental studies are beginning to demonstrate that the thirst/ADH system is probably by far the most potent mechanism that we have for control of extracellular fluid sodium ion concentration. On the other hand, the aldosterone mechanism seems to be our primary control system for maintaining a normal extracellular fluid concentration of potassium.
Author List
Guyton AC, Cowley AW Jr, Young DB, Coleman TG, Hall JE, DeClue JWAuthor
Allen W. Cowley Jr PhD Professor in the Physiology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Angiotensin IIAnimals
Blood Circulation
Blood Pressure
Blood Volume
Body Fluids
Cardiac Output
Cardiomegaly
Cardiovascular Physiological Phenomena
Cardiovascular System
Dogs
Hemodynamics
Homeostasis
Humans
Kidney
Oxygen Consumption
Reflex
Regional Blood Flow
Renin