Of cows and calculus: how mammals regulate blood calcium with precision

Mustafa Khammash
Department of Biosystems Science and Engineering
Basel, Switzerland


In mammals, maintaining the blood concentration of calcium within small tolerances is crucial for the function of many physiological processes, including proper nerve and muscle function. The regulation of calcium is achieved by an exquisite feedback control mechanism that ensures constant plasma calcium levels in spite of disturbances that would otherwise push the system away from equilibrium. Using a simple mathematical model, we show how this feedback mechanism functions dynamically to achieve robust set-point tracking. In particular, we demonstrate that the perfect adaptation property of mammalian calcium regulation system imposes stringent constraints on the structure of the regulatory system. Such constraints lead to a new understanding of the role of the hormones involved in calcium regulation. The elucidation of the dynamics of the calcium homeostatic system sheds light on parturient paresis, a common disease associated with calving in dairy cows.