The HR
and BP are lower at rest, while the HR picks up
and BP is elevated during emotional stress
and exercise. The control of the HR and BP are with the sympathetic and parasympathetic nervous system. The former increases the HR and BP while the latter reduces them.
Marciamcm,
Normally, the sympathetic and parasympathetic nervous system work together in a very efficient and cooperative manner. From time to time, this system breaks down in people with NMS.