Which describes the heart’s pacemaker?
a. It sends signals that make the heart expand.
b. It removes wastes from the bloodstream.
c. It adjusts heart rate based on oxygen needs.
d. It is located in the right ventricle of the heart.
a. It sends signals that make the heart expand.
b. It removes wastes from the bloodstream.
c. It adjusts heart rate based on oxygen needs.
d. It is located in the right ventricle of the heart.