The Transfer Function Relating Hypophyseal Response to Hypoglycemia in Man

Abstract

Experiments have been undertaken to develop preliminary data regarding quantitative aspects of the control and regulation of the level of serum growth hormone. Responses measured in human test subjects during insulin induced hypoglycemia suggest that the pituitary gland behaves like a critically damped system. In order to provide information which would be useful in predicting hypophyseal response, a simplified mathematical model was formulated. Confirmation that the equations are valid in the region of the time domain considered strengthens our conviction that the model can be used to make predicitons in the frequency domain. Since diseased or defective homeostatic mechanisms may impair the capability of the pituitary gland to control the secretions of growth hormone, open and closed loop transfer functions were obtained. Our analysis predicts that open loop conditions will result in hormonal oscillations, the nature of the oscillations depending on the values of the physiological sensitivities.