The primary factors that affect circulation - MABP, CO and SVR
Date Uploaded: 10/09/2019
Tags: homeworkclinic.com Homework Clinic HWC arterial blood pressure systemic vascular resistance Mean arterial blood pressure Cardiac output Vessel radius Blood viscosity العوامل الرئيسية التي تؤثر على الدورة الدموية
Introduction Blood flow is determined by the relative intensities of factors that drive and resist moving blood. • Cardiac output (CO) equals the mean arterial blood pressure (MABP, a driving force) divided by systemic vascular resistance (SVR, a resisting force). • Hormones and the central nervous system both influence and regulate MABP or SVR and impact CO. The primary factors that influence circulation arc: • Mean arterial blood pressure. • Systemic vascular resistance. • Cardiac output. • Blood flows from areas of higher pressure to areas of lower pressure. • The pressure gradient, determined by pressure differences in blood ejected from the heart (MABP) and that entering the right atrium (right atrial pressure), determines systemic blood flow. • Right atrial pressure is so low that blood flow is directly proportional to only MABP. • The greater the pressure gradient, the greater the flow. Cardiac output (CO) is: ■ Measure of blood ejected by ventricles over a given time. • Product of heart rate and stroke volume. • Influenced by venous return (preload), contractile strength of heart, and metabolic demands. The greater the cardiac output then the greater the blood flow. • Systemic vascular resistance is the natural dampening of blood flow. ■ The greater the resistance, the harder it is to move blood through the vessel. ■ Factors that increase resistance are: • Vessel radius - the smaller the radius, the greater the SVR. • Blood viscosity - the thicker the blood, the greater the SVR. ■ Vessel length - the greater the length, the greater the SVR. • The greater the resistance the greater cardiac output (and blood pressure) must be to overcome the resistance.
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