Final answer:
The sum of all the vascular resistance within the systemic circulation is known as systemic vascular resistance (SVR), which is influenced by vessel diameter, blood viscosity, total length of vessels, and mean arterial pressure.
Step-by-step explanation:
The sum of all the vascular resistance within the systemic circulation is called the systemic vascular resistance (SVR), also known as peripheral vascular resistance. This measure is crucial for understanding how much resistance the heart must overcome to pump blood through the body's network of vessels. Factors that affect SVR include vessel diameter, blood viscosity, and the total length of vessels.
For instance, a slight vasodilation significantly decreases resistance and increases flow, whereas slight vasoconstriction greatly increases resistance and decreases flow. Additionally, resistance is influenced by the mean arterial pressure, which is the average pressure driving blood into the tissues during the cardiac cycle.