Straining at stool initiates the Straining at stool initiates the .
maneuver that results in a potentially dangerous increase in BP.
maneuver that results in a potentially dangerous increase in BP.

valsalva

Explanation:

Straining at stool initiates the Straining at stool initiates the valsalva maneuver that results in a potentially dangerous increase in BP. This maneuver is a particular way of breathing which increases pressure in the chest. Due to this, there are enormous effects in the body which includes the changes the blood pressure and heart rate.

answer; the parasympathetic nervous system;