Which of the following mechanisms play a role in regulating heart rate?
A)chemical messengers in the blood,such as epinephrine
B)nerves originating from the medulla (lower part of the brain)
C)pacemaker cells within the heart
D)all of the above (A to
E)only A and C

Question

Quizplus · Accepted Answer

All three mechanisms play a role in regulating heart rate. Chemical messengers in the blood, such as epinephrine, can increase heart rate. Nerves originating from the medulla can both increase and decrease heart rate, depending on the type of nerve fibers involved. Pacemaker cells within the heart generate electrical impulses that initiate each heartbeat and can set the overall rhythm of the heart. Therefore, all of the above mechanisms are involved in regulating heart rate.

Which of the Following Mechanisms Play a Role in Regulating