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The pulmonary and the systemic circulations are the two parts of the vasculature. The pulmonary circulation system consists of the network of blood vessels from the right heart to the lungs and back to the left heart. The rest of the blood flow loop is called systemic circulation system.
Vascular resistance is the resistance that must be overcome for blood to flow through the circulatory system.The resistance offered by the systemic circulation is known as the systemic vascular resistance or may sometimes be called by another term total peripheral resistance, while the resistance caused by the pulmonary circulation is known as the pulmonary vascular resistance.
A number of medical conditions may affect the pulmonary circulation: Pulmonary hypertension describes an increase in resistance in the pulmonary arteries. [9] Pulmonary embolism is occlusion or partial occlusion of the pulmonary artery or its branches by an embolus, usually from the embolization of a blood clot from deep vein thrombosis. [10]
The systemic circulation is a circuit loop that delivers oxygenated blood from the left heart to the rest of the body, and returns deoxygenated blood back to the right heart via large veins known as the venae cavae. The systemic circulation can also be defined as two parts – a macrocirculation and a microcirculation.
The net effect of these changes is that the width of the PV loop is increased (i.e., ventricular stroke volume is increased). However, ejection into the aorta (forward flow) is reduced. The increased ventricular stroke volume in this case includes the volume of blood ejected into the aorta as well as the volume ejected back into the left atrium.
Diastolic dysfunction is associated with a reduced compliance, or increased stiffness, of the ventricle wall. This reduced compliance results in an inadequate filling of the ventricle and a decrease in the end-diastolic volume. The decreased end-diastolic volume then leads to a reduction in stroke volume because of the Frank-Starling mechanism. [1]
Airway resistance can also change over time. During an asthma attack the airways constrict causing an increase in airway resistance. Airway resistance can also vary between inspiration and expiration: In emphysema there is destruction of the elastic tissue of the lungs which help hold the small airways open. Therefore, during expiration ...
A pulmonary-to-systemic shunt is a cardiac shunt which allows, or is designed to cause, blood to flow from the pulmonary circulation to the systemic circulation. [1] [2] This occurs when: there is a passage between two or more of the great vessels; and, pulmonic pressure is higher than systemic pressure and/or the shunt has a one-way valvular ...