In the aorta the blood pressure and blood velocity are both high?

Answer 1

The pressure in the aorta is essentially steady, with a descending gradient between that at the proximal aorta and its junction with major arteries, so the 'ambient' internal pressure steadily diminishes along the traverse. The injections of stroke volumes of blood (initially at systolic pressure) do give rise to transient peaks of pressure at the central aorta, but these do not raise the pressure of the body of the elastic plenum comprising the aorta and larger arteries significantly, because the injected stroke volume is almost negligible in comparison. However, because the injected volume displaces blood already in the aorta, the walls expand with the additional pressure, and this mechanism sets a longitudinal traveling pulse pressure wave in motion. As it passes any point along its path a transient peak of pressure is observed, but this performs no work on the moving blood -apart from almost negligible losses en passant. So, the speed of the steady flow of blood is slow. The pressure peaks are higher. The speed of the pulse pressure peaks is high The expression 'the blood pressure' is meaningless in this context because it varies constantly all along the gradient existing along the arterial tree.