Calcium is critically important for a vast array of cellular functions, as can be seen by a quick look through any physiology book. For example, in this book we discuss the role that Ca2+ plays in muscle mechanics, cardiac electrophysiology, bursting oscillations and secretion, hair cells, and adaptationin photoreceptors, among other things. Clearly, the mechanisms by which a cell controls its Ca2+ concentration are of central interest in cell physiology.
There are a number of Ca2+ control mechanisms operating on different levels, all designed to ensure that Ca2+ is present in sufficient quantity to perform its neces sary functions, but not in too great a quantity in the wrong places. Prolonged high cytoplasmic concentrations of Ca2+ are toxic. For example, cellular Ca2+ overload can trigger apoptotic cell death, a process in which the cell kills itself. In muscle cells, high intracellular Ca2+ is responsible for prolonged muscle tension and rigor mortis.
KeywordsBifurcation Diagram Homoclinic Orbit Release Site Ryanodine Receptor Spiral Wave
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