Embodiments of a blood coagulation testing system can operate as an automated thromboelastometry system that is particularly useful, for example, at a point-of-care site. In some embodiments, the blood coagulation testing system includes a single-use cartridge component configured to measure and mix reagents with blood received from a blood sample reservoir. A mixing chamber in the single-use cartridge includes different reagent beads that, when exposed to a pre-determined volume of blood, dissolve and mix specific reagents with the blood. The assembled blood cartridge further includes configurations that are designed to prevent blood from prematurely mixing with reagent beads in the mixing chamber and to guide blood flow in the mixing chamber to dissolve reagent beads in a desired order. Thus, the mixture obtained from the mixing chamber can be readily utilized to generate results for the blood coagulation testing system.