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CARDIOVASCULAR PHYSIOLOGY    Overview of thc Cardiovascular System

Pulmonary

Low pressure system

(reservoir function)

J. Pcrkins

-m.n

High pressure system

(supply function)

Aortic pressurc: 120/80 mm Hg fmean pressure 95 mm Hg)

Figurę 4.1 Cardiovascular System Overview „

The cardiovascular system consists ot the heart. which pumps blood inlo thc pulmonary circulation (or lite exchange of O, and CO, and into the systemie circulation to supply all other tissues of the body.

At rest, cardiac output is approximately 5 L/min in both the pul monary and systemie circulations. The amount of blood flow (Q) las a percentage of cardiac output) and relative percentagc of oxygen UtHization per minutę (Vo,) to various organ systems is shown for the resting State. The systemie circulation is arranged in a parałlel fashion (brain, heart. gastrointestinal tract, etc ). Based on metabolic need and demand. both Q and Vc>₇ may be adjusted. At any one time. most of the blood volume resides in the veins (64%) and is returnetl to the right side of the heart. Vascular resistance is primarily a function of the smali musi ular arleries and arterioles.

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