Final answer:
Blood pressure is lowest in the capillaries due to the large total cross-sectional area. The body compensates through vasodilation and vasoconstriction of arterioles and the elasticity of arterial walls, ensuring proper blood flow is maintained throughout the body.
Step-by-step explanation:
Blood pressure is lowest in the capillaries, which are the smallest blood vessels. This low pressure is due to the combined large total cross-sectional area of the capillary beds despite the narrow diameter of an individual capillary. To compensate for the low pressure and maintain adequate blood flow, the body uses mechanisms such as the contraction of smooth muscle in the arterioles to regulate blood pressure (vasodilation and vasoconstriction) and the elastic properties of arteries to help pump blood during the cardiac cycle.
Additionally, the fluid pressure of the blood itself and the action of one-way valves in veins help return blood to the heart against the low pressure gradient. The optimal systolic blood pressure is 120 mmHg, and the optimal diastolic blood pressure is 80 mmHg, which measures the pressure in your arteries during heartbeats and between them, respectively. Various factors can influence blood pressure, including hormones, stress, exercise, and posture.