Withdrawal of parasympathetic influence on the heart results in…- an increase in HR. – a decrease in HR.- a small decrease in arterial blood pressure.- a small decrease in arterial blood pressure followed by an increase in HR.
an increase in HR.
Withdrawal of parasympathetic influence on the heart results in an increase in heart rate. The parasympathetic nervous system is known to decrease the heart rate, while the sympathetic nervous system increases it. When the parasympathetic influence on the heart is withdrawn, the sympathetic nervous system becomes more active, resulting in an increase in heart rate. This occurs due to the activation of beta-adrenergic receptors in the heart by catecholamines such as adrenaline and noradrenaline, which stimulate the pacemaker cells of the sinoatrial node to increase their rate of firing and thus increase the heart rate.
Withdrawal of parasympathetic influence on the heart also results in a small increase in arterial blood pressure due to the stimulation of alpha-adrenergic receptors by catecholamines, leading to vasoconstriction. However, this increase is generally overshadowed by the increase in heart rate, and, in fact, there is often a small decrease in arterial blood pressure initially due to the loss of parasympathetic tone on the vasculature.
More Answers:
Discover How Your Pulmonary System Works: Supplying Oxygen and Eliminating Waste GasesUnderstanding Systole: The Heart’s Contraction Phase for Blood Circulation
How Exercise Affects Diastole and Systole: Understanding the Impact on Heart Rate and Blood Flow