Final answer:
Blood pressure in the arteries is highest during systole, the phase of the cardiac cycle when the heart contracts, causing the artery walls to stretch. Systolic pressure usually measures around 120 mm Hg and diastolic pressure about 80 mm Hg.
Step-by-step explanation:
During the cardiac cycle, blood pressure is highest in the arteries during systole, which is the phase when the heart contracts and ejects blood. The artery walls stretch to accommodate the extra blood, causing an increase in pressure. In contrast, during diastole, which is the phase when the heart muscle relaxes and the ventricles fill with blood, artery walls return to their normal state and blood pressure decreases. Systolic pressure is the top number in a blood pressure measurement and is typically around 120 mm Hg, while diastolic pressure is the bottom number and is usually about 80 mm Hg.
The hydrostatic pressure of the blood against the artery walls during systole and diastole gives the two pressure readings for blood pressure, like the commonly referenced 120/80 mm Hg. The high systolic pressure is indicative of the arterial pressure during the ventricular contraction, and the lower diastolic pressure represents the arterial pressure when the ventricles are at rest.