"diver's reflex" is a response to diving in many aquatic mammals and also occurs in humans upon submersion in water. it is characterized by physiological changes that decrease oxygen consumption, such as a slowed heart rate. which region of the heart would be directly affected by the nervous system to allow for the slowing of heart rate?

The answer is Sinoatrial node.

Explanation:

The sinoatrial node are the group of cells in the wall of right atrium of the heart.

The animals tend to initiate diving response when diving, this is the reduction in heart rate, which triggered respiratory arrest response and stimulation of facial code receptors.

This is the physiological adaptation allowing animals to cope with lack of oxygen.