Veins are small so capillary action keeps things in order.
With no gravity though you’ll have higher blood pressure to your head (and less to the legs)- it kinda makes astronauts faces a bit puffy. iirc this can slightly negatively affect vision long term.
Most of your body processes are in a small enough space that capillary action overtakes gravity.


















Technically if they did that fast enough the blood pressure on both would get higher, potentially MUCH higher.