Question

A 30 year old patient exercises about 45 minutes/4 to 5 times a week.His resting HR is 74 and when exercising increases to about 130bpm.Which of the following is a property of the SAN cells that gives the role as a natural pacemaker of the heart?

A)Activation of fast Na+channel in the phase 0

B)Steeper phase 4

C)The large negative of the maximum diastolic potential

D)Longer Phase 2

E)Faster depolarization phase

Answer 1

Ans:- B)Steeper phase 4

All other options are wrong which is cleary visible from above explaination.