1.4 Cardiac physiology
In order to interpret auscultatory findings and to appreciate the pathophysiolochanges in normal and diseased animals, it is particularly important to understand the mechanical and electrical events which occur during the cardiac cycle. The movement of blood is dependent on pressure gradients between the chambers and the great vessels. The pressure gradients are affected by sigdisease processes and changes in these pressure gradients are responfor signs of congestive heart failure (see section 2.2.1). The acceleration and deceleration of blood during the cardiac cycle is responsible for the normal transient sounds heard during auscultation. The pressure gradients and the rate of change of the gradients are responsible for the characteristics of cardiac murmurs which may occur with normal and abnormal blood flow. The pressures within the atria, ventricles and aorta at different points during the cardiac cycle are shown in Figure 1.4.
1.4.1 The cardiac cycle
1.4.2 Autonomic control of the cardiovascular system
1.4.3 Control of cardiac output
1.4.4 Control of blood pressure
1.4.5 Myocardial oxygen consumption
1.4.6 Myocardial wall tension