A 66-year-old man, who has had a sympathectomy, experiences a greaterthan-normal fall in arterial pressure upon standing up. The explanation for this occurrence is

Question

Quizplus · Accepted Answer

[IX A]. Orthostatic hypotension is a decrease in arterial pressure that occurs when a person moves from a supine to a standing position. A person with a normal baroreceptor mechanism responds to a decrease in arterial pressure through the vasomotor center by increasing sympathetic outflow and decreasing parasympathetic outflow. The sympathetic component helps to restore blood pressure by increasing heart rate, contractility, total peripheral resistance (TPR), and mean systemic pressure. In a patient who has undergone a sympathectomy, the sympathetic component of the baroreceptor mechanism is absent.

A 66-Year-Old Man, Who Has Had a Sympathectomy, Experiences a Greaterthan-Normal