Final answer:
The upper range of ventricular contractions is 200 beats per minute due to the refractory period of the AV node which consists of a 200 ms absolute and 50 ms relative refractory periods. Option number 1 is correct.
Step-by-step explanation:
The upper range of ventricular contractions in the human heart, due to the relatively long refractory period of the AV node is limited. The refractory period consists of the absolute refractory period, which lasts approximately 200 ms, and the relative refractory period, which lasts approximately 50 ms. Consequently, for the heart to pump blood effectively, a contraction must follow the electrical events, leading to an upper limit of how fast the heart can beat.
Given that the AV node with extreme stimulation by the SA node can transmit impulses maximally at 220 per minute, this establishes the typical maximum heart rate in a healthy young individual. Therefore, the correct answer to the question of what is the upper range of ventricular contractions in the human heart is 200 beats per minute.