Chapter 20, Problem 7WWTS

Summary Introduction

Introduction:

Only in the pulmonary circuit of the lungs, the arteries carry de-oxygenated blood and veins carry oxygenated blood. When compared to systemic unit, the pulmonary artery has distensible walls with less elastic tissue and blood pressure is about 25/10 mm Hg. The systemic capillaries have hydrostatic pressure of about 17 mm Hg, while the pulmonary has 10 mm Hg. This low pressure has two major implications in pulmonary circulation. Firstly, there is more time for gas exchange due to slow flow of blood. Secondly, the hydrostatic pressure is overridden by the oncotic pressure, and the capillaries are engaged only in the absorption. This action prevents fluid accumulation in the lumens and alveolar.