When you stand up from a reclining position, there is a substantial shift of bloog from the veins of the thoracic cavity to the veins of your lower extremities. This pooling of blood reduces venous return and hence cardiac output, resulting in a decrease in blood pressure. If I did not see a difference in pulse pressures between reclining and standing positions, can you offer an explanation for why you did not see a difference in pulse pressure between the two body positions?