What two nerves affect the rate of heartbeat how are they affected?

The vagus nerve and the sympathetic nerves affect the rate of heartbeat.

The vagus nerve is a parasympathetic nerve that slows down the heart rate when active. It is like the brakes on a car.

The sympathetic nerves are part of the sympathetic nervous system, which is responsible for the body's "fight or flight" response. When the sympathetic nerves are active, they speed up the heart rate. It is like the gas pedal on a car.