What is the effect of posture (i.e. sitting, standing, lying down for 1 minute, lying down for 10 minutes and standing after lying down) on blood pressure and pulse rate. What systems are involved and why?
Effect of Posture on Heart Rate and Blood Pressure
Effects of posture on heart rate and blood pressure are mediated by neural regulation through baroreceptors. Nerve cells capable of responding to changes in pressure or stretch are called "baroreceptors." These receptors that are in the walls of the arteries and veins monitor blood pressure and help to maintain normal blood pressure when changes occur.
Let's begin with the carotid sinus reflex. This is a negative feedback system that helps maintain blood pressure when baroreceptors in the wall of the carotid sinus receive stimulus. The carotid sinus is a small widening of the internal carotid artery just above the point where it branches from the common carotid artery.
When you stand up, blood pressure decreases. As a result, the baroreceptors in the arch of the aorta and in the carotid sinus are stretched less. This is the input. This results in a decreased rate of nerve impulses to the ...