Final answer:
Increasing levels of calcium ions in the heart lead to increased heart rate and contractility. High calcium levels result in ECG changes and in extreme cases, can cause cardiac arrest. The experiment's results support the hypothesis that calcium imbalances affect heart functionality.
Step-by-step explanation:
The effect of increasing calcium ions on the heart is significant, as calcium plays a crucial role in the physiology of cardiac muscle function. With an increase in calcium ion levels, there is an increase in both heart rate (HR) and contractility. This is because calcium ions facilitate the influx through slow calcium channels during the plateau phase, contributing to the refractory period necessary for proper cardiac function. Calcium also binds to the protein troponin, enabling the myosin heads to form cross-bridges with actin, thus powering muscle contraction.
A rise in calcium levels can lead to a shortened QT interval and a widened T wave on an ECG, indicators of hypercalcemia. In extreme cases, very high levels of calcium can lead to cardiac arrest. On the other hand, calcium channel blockers are used to reduce heart rate by inhibiting the inflow of calcium ions. Therefore, the results observed with increased calcium levels would support the hypothesis that calcium is crucial for proper heart function and that imbalances can have serious physiological impacts.