Abstract: A "heart" unit serving as a partial analog system of the human body for demonstrating physiological events which occur during the growth of a brain tumor, including cardiac and respiratory failure during rapid tumor growth, for teaching purposes and the like, including an analog of the heart with fluid pumping means for inducing a pulsing flow; an analog of the respiratory muscles with means for inducing a secondary pressure pulse; an analog of the circulatory system including circulating fluid upon which said analog heart induces a pulsing flow and said respiratory muscles induce a pressure oscillation; an analog of the cranial cavity; an analog of a brain tumor with supplemental means for displacing a portion of the intracranial cavity; and an analog of the cerebral fluid within analog ventricles with means to flow in and out of the cranial cavity via analog subarachnoid paths to equalize cerebral pressure with the circulatory system pressure outside of the cranial cavity.