Concept 4 Review

Factors Influencing Blood Pressure

Blood pressure has a pulse, or both a systolic and diastolic reading. These high and low readings are due to the surge of blood caused by left ventricular contraction (systole), followed by left ventricular relaxation. Because of peripheral resistance, the pulse is smoothed out as blood moves away from the heart through the arterial system and, by the time blood is passing through the arterioles, surges are no longer apparent.

Examine the graphic carefully to see how blood pressure varies throughout the cardiovascular system.

Blood pressure (BP) in the arterial system is influenced by

In general, BP varies directly with both cardiac output and blood volume; as cardiac output and blood volume go up, so does blood pressure. Because of peripheral resistance, pressure is highest in the aorta and large arteries. It drops as blood enters smaller arteries and falls drastically as blood moves through the systemic arterioles. Amazingly, blood pressure at the arterial end of a capillary is just high enough to move the blood to the venule end. Blood pressure in the large veins falls to zero!