Final answer:
The inherent rate of the SA node is 80-100 impulses per minute, followed by the AV node at 40-60, the atrioventricular bundle at 30-40, the bundle branches at 20-30, and the Purkinje fibers at 15-20 impulses per minute.
Step-by-step explanation:
The inherent rates for each of the automaticity foci in the heart can be outlined as follows: The SA node has an inherent rate of 80-100 impulses per minute. If the SA node is not functioning, the AV node takes over with an inherent rate of 40-60 beats per minute. Should the AV node also fail, the atrioventricular bundle becomes the pacemaker with a rate of 30-40 impulses per minute. The next level down, the bundle branches, would fire at a rate of 20-30 impulses per minute, and finally, the Purkinje fibers would fire at 15-20 impulses per minute. Rates lower than 50 beats per minute in individuals who are not exceptionally trained athletes may indicate a condition called bradycardia. Bradycardia can lead to inadequate blood flow, loss of bodily function, unconsciousness, and in severe cases, death.