1 LECTURE 1 1. Introduction to the Course These courses are going to cover four major topics: cardiovascular physiology, respiratory physiology, renal physiology, and then digestive physiology. 1A. Cardiovascular Physiology Were going to start out with lectures looking at the function of the cardiovascular system, so today, well begin by looking at electrical activity in the heart: well look at how electrical activity is conducted through the heart from the endogenous pacemaker through to contractile cells youve all heard of implantable pacemakers, but there is an endogenous group of cells in the heart that function as the normal pacemaker in normal, nonpathological situations. In the next lecture, were going to look at the ECG (electrocardiogram), which produces that generally familiar heartbeat pattern, and well see what the various deflections, and periods between deflections, represent; as well, well see how you can use an ECG to determine whether a heart is functioning normally, or to diagnose disease or abnormal states. Well then look at whats called the electrical axis of the heart, which is the general, overall direction that electrical activity flows in the heart; again, this is a very useful diagnostic tool that can tell you whether there are various disease states in the heart. The axis can deviate from its normal direction, either to the left or the right, and which direction it goes and the extent to which it deviates can assist you in diagnosing problems. The cardiac cycle, the focus of the next lecture, tells about the various pressure and volume changes, the opening and closing of valves, and the contraction of atria and ventricles that occur during a single beat of the heart (or cardiac cycle). Were then going to look at regulation of cardiac output (cardiac output refers to the amount of blood the heart puts out per unit of time), and regulation of blood flow, and then heart failure and blood pressure. 1B. Respiratory Physiology When we come to respiratory physiology, well begin by looking at pulmonary mechanics, i.e., the pressure and volume changes, muscle contraction, and other factors that are associated with a single inspiration and expiration. Well look at a technique of spirometry, which is used to measure lung volumes and capacities. Again, these are important diagnostic tests, and can be used to diagnose, for instance, whether someone has an obstructive lung disease, a restrictive lung disease, or whether the lung is functioning normally. Alveolar ventilation looks at how the air that we breathe in actually gets into the gas exchange site, the alveoli, and how this can be modified by changing breathing rate and tidal volume and how they are egulated.