Advances in Physiology Education, Vol 270, Issue 6 40-S49, Copyright © 1996 by American Physiological Society
Graphic format for teaching long-term control of systemic arterial pressure
J. J. Faber
Department of Physiology and Pharmacology, School of Medicine, Oregon Health Sciences University, Portland 97201-3098, USA.
Circulatory homeostasis is a difficult notion. The graphic format presented
here facilitates the teaching of long-term control of systemic arterial
blood pressure and cardiac output. It is based on the view that the
following four "function curves" cooperate in long-term regulation: the
relation between blood volume and ventricular filling pressure, the
relation between ventricular filling pressure and cardiac output, the
relation between cardiac output and peripheral resistance, and the relation
between arterial pressure and natriuresis. Positioning the function curves
in the format presented here clarifies their cooperativity. The distinction
between a nonsteady state and a steady state deserves emphasis. Long-term
pathophysiology of the circulation is most easily taught on the basis of
the assumption that, generally, there will be a steady state. The format
clarifies why some known physiological relations are almost impossible to
demonstrate in the intact organism, and it discourages explanations of
pathophysiology that are not firmly based on physiology.
