Blood pressure is governed by five elements--the strength of the heartbeat, the volume of blood, the viscosity of the blood, the resistance of the arterioles, and the elasticity of the arterial walls. An abnormality of any of these can cause the blood pressure to be too high or too low.
Depending on the complexity of the case a trial can last anywhere from one day to six months or longer. If you are asking how long a rape prosecution takes you are probably looking at 6 months to a couple of years.
How long will I be there? Regular jurors are scheduled for two days of service or the length of the trial for which they may be selected. The average trial length in Milwaukee County is 1-3 days. Very few trials are sequestered (kept overnight) so you can expect to go home around 5:00 pm. Every court operates on its own hours and occasionally keeps jurors past 5:00 pm.