Introduction to the respiratory system

Published on September 29, 2022   32 min

A selection of talks on Physiology & Anatomy

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Hello, I'm Jeremy Ward, Emeritus Professor for Respiratory Cell Physiology at King's College London. I was Head of the Department of Physiology for ten years and for two years was Head of the Department of asthma, Allergy and Lung Biology. I'm going to be talking about the respiratory system.
The topics I'm going to cover include, what is the respiratory system? Why is it important? The carriage of O_2 and CO_2 because that is one of the main functions of the respiratory system. Basic structures and functions, the process of breathing, the mechanics of breathing, and the control of breathing. I'm going to finish off with a very brief introduction to some common diseases of the respiratory system. Before we go on, just note that PO_2 or PCO_2 denotes the partial pressure of that gas. In other words, the pressure that gas exerts as a proportion of atmospheric pressure. If atmospheric pressure is 100 kPa and air contains 21% O_2, the PO_2 is 21 kPa. Note that confusingly, by convention blood pressure is still expressed in millimeters of mercury (mmHg), not SI units.
What is the respiratory system? You can see a cartoon of the major components. It includes a series of conducting airways which carry air from the mouth, nose to the lungs, which is where, of course, gas exchange of O_2 and CO_2 occurs. The right side of the heart pumps deoxygenated blood from the veins and tissue through specialised blood vessels in the lung (called the pulmonary circulation), to enable gas exchange, before returning the reoxygenated blood to the left side of the heart for pumping around body and to the respiring tissues. The respiratory system also includes the muscles that enabled breathing, including, most importantly, the diaphragm and the intercostal muscles between the ribs.