Asked by Addie Mejia on May 11, 2024
Verified
Which of the following best explains the drop in blood pressure that occurs when one goes from lying down to standing up?
A) The heart rate decreases. This is due to the baroreceptor reflex reducing sympathetic output to the SA node.
B) An increase in afterload causes a drop in stroke volume, cardiac output, and blood pressure.
C) An increase in preload causes a drop in stroke volume, cardiac output, and blood pressure.
D) Venous compliance allows blood to pool in the legs, decreasing venous return. This causes a drop in cardiac output and blood pressure.
Baroreceptor Reflex
Detects changes in blood pressure and produces changes in heart rate, heart force of contraction, and blood vessel diameter that return blood pressure to homeostatic levels.
Sympathetic Output
The activity or signals generated by the sympathetic nervous system, which is involved in the body's fight-or-flight response.
SA Node
The SA node, or sinoatrial node, acts as the heart's natural pacemaker, initiating the electrical impulse that triggers heart contractions and regulates heart rate.
- Understand the physiological mechanisms that regulate blood pressure and heart rate.
Verified Answer
TL
Thuy Ly NguyenMay 17, 2024
Final Answer :
D
Explanation :
When one goes from lying down to standing up, gravity causes blood to pool in the legs. This increases venous compliance, which decreases venous return to the heart. With less blood returning to the heart, the cardiac output decreases, leading to a drop in blood pressure. This is a physiological response and is typically counteracted by the baroreceptor reflex, which increases heart rate and vascular resistance to maintain blood pressure.
Learning Objectives
- Understand the physiological mechanisms that regulate blood pressure and heart rate.