This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
A person stands up. Compared with the recumbent position, 1 minute after standing, the 
Select and explain. 
A. Skin blood flow increases, B. Volume of blood in leg veins increases, C. Cardiac preload increases, D. Cardiac contractility decreases
B: Volume of blood in leg veins increases
Answer: B: Volume of blood in leg veins increases 
Explanation: Standing up increases the transmural pressure in the veins of the legs. Because the veins are highly compliant, their volume increases at the expense of central blood volume.A lower central blood volume means reduced cardiac filling pressure (preload). Within seconds, the decrease in preload decreases stroke volume, cardiac output, and aerial pressure.