Final answer:
Key factors in cardiovascular function include mean arterial pressure, maximal oxygen consumption, and blood flow, with cardiac output being central to these.
Step-by-step explanation:
Understanding Blood Circulation Variables
The cardiovascular system is regulated by various factors that influence mean arterial pressure (MAP), maximal oxygen consumption (VO2 max), and blood flow. MAP can be defined using the formula MAP ≈ (2 * diastolic + systolic) / 3 and represents the average pressure driving blood into tissues. VO2 max is an indication of aerobic fitness and is calculated using the formula VO2 max = cardiac output * (a-vo2 difference), where cardiac output is the amount of blood the heart pumps in a minute. Blood flow is governed by factors such as vessel diameter and resistance, described by Poiseuille's equation.
Factors affecting cardiac output, central to blood pressure and flow, include heart rate (HR), stroke volume (SV), and systemic vascular resistance. HR and SV are directly responsible for cardiac output (CO = HR * SV), with an increase in either resulting in a higher CO, thus elevating blood pressure and promoting blood flow. Resistance plays a key role in determining blood flow according to the equation flow = pressure/resistance, where resistance is affected by vessel length, viscosity, and diameter.
Within the venous system, blood flow is influenced by venous tone, the skeletal muscle pump, the respiratory pump, and venous valves, which work collectively to return blood to the heart. Constriction of veins (venoconstriction) can increase blood pressure while working synergistically with valves and muscle contractions to aid venous return.