Hemodynamic System and the Mechanism of Blood Flow

Hemodynamics: Research Paper
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Hemodynamics: Research Paper
Introduction
The study of hemodynamics deals with the physical principles that govern the distribution of blood flow and pressure within the vascular system. The circulatory system is comprised of the heart and a network of the branched vascular system that contains blood, which functions in the transportation of oxygen, nutrients, and heat in the body (1). Important factors considered in hemodynamics include the heart’s pulsatile pressure, blood flow characteristics, and the mechanical properties and geometric structure of blood vessels. In understanding the link between the driving pressure of the heart and blood flow in a vessel, it is critical to consider the inertial and viscous forces that act on the blood (2). Several flow events occur depending on the diameter of the vessels as well as other physical characteristics. The forces that act on the walls of vessels are circumferential stress, which is caused by blood pressure and shear stress that results from the flow of blood. These forces are the primary causes of various biological responses that are key to the structural vascular remodeling and control of blood flow that are also important in disease processes such as atherosclerosis and hypertension (1). To appreciate the role of hemodynamics in pathophysiology, it is important to understand the hemodynamic system, the mechanism of blood flow, and the importance of monitoring hemodynamics.
Hemodynamic System
The main principles that constitute the hemodynamic system include cardiac output (CO), heart rate, stroke volume, blood pressure, and systemic vascular resistance. These concepts are related in that the heart/pulse rate or the heart beats per minute and stroke volume or the amount of blood pumped during ventricular contraction determine the CO (3). CO is the amount of blood pumped by the heart in a given time and is a measure of the efficiency of the heart to circulate blood throughout the body based on the demands. Like in an electrical circuit, the pathway of blood flow in the body is impacted by the resistance to flow that the blood vessels exert. This concept of CO follows Ohm's law, which states that the current that passes through conduct is equivalent to the voltage over resistance (4). Therefore, systemic resistance of the vascular system refers to the resistance which the heart must endure to effectively supply blood in the body. Following this principle, blood pressure is derived by multiplying the resistance by CO. Both osmotic pressure and hydrostatic pressure help maintain the right amounts of extravascular and intravascular volumes. While osmotic pressure due to dissolved solutes pulls fluids into interstitial tissues and vessels, hydrostatic pressure pushes fluids into vessels. Any imbalance in these pressures leads to abnormal fluid distribution in interstitial tissues or edema (5). Impaired CO, which can be caused by heart failure, results in the body having challenges in managing the daily demands because it results in a decline in available oxygen to body tissues and organs.
Mechanism of Blood Flow
Tissue blood flow guarantees oxygenation of tissues and organs and the delivery of oxyg...