THERMOSENSITIVITY OF THE TURTLE BRAIN AS MANIFESTED BY BLOOD PRESSURE CHANGES

Abstract

A temp.-sensitive center, manifested by thermally induced blood pressure changes, is present in the brain of the turtle, a cold-blooded animal. Direct warming of the turtle brain results in a rise in blood pressure, while cooling results in a fall in pressure. The degree of the response is dependent upon the intensity of the thermal stimulus and upon the site of stimulation. The most sensitive site was found to be at the level of the 3d ventricle. The significance of these results in terms of physiological adjustment of the poikilotherm to environmental temp. changes, and in terms of the evolution of homeothermus is discussed.