Pacemaker cells in the heart possess intrinsic rhythm.
a. true
b. false

True

Explanation:

Pacemaker cells, unlike other neurons in the body, can depolarized themselves (and therefore can fire action potentials) without the need of an external innervation of the autonomic nervous system.  

Each class of pacemaker cells has its own intrinsic rate.

For example, sinoatrial node rate is 60-100 bpm (the normal heart frequency).  

The atrioventricular node is also part of the electrical conduction system of the heart. When the sinoatrial node fails, atrioventricular node takes the lead (40-60 bpm).