Ventricular Contraction Recovery

ABSTRACT: By using the scientific method, the effects of exercise and recovery time on the heart rate and cardiac output will be examined. By listening to the heart at rest before exercise, after three minutes of exercise, one minute of recovery and using the radial and apical pulses to measure their change.

INTRODUCTION: The human heart is a contractile specialized muscular four chambered organ of the circulatory system that perpetually pumps blood throughout the human body. This specialized organ of the circulatory system is designed to continuously supply nutrients to the tissues of the body by supplying it with oxygenated rich blood and removing the oxygen poor blood along with any waste products. The heart muscle has been constructed

They enter the papillary muscles first so they contract, causing the chordae tendineae to pull tight, and that closes the AV valves. The action potentials, then go throughout the ventricles and cause the QRS which cause ventricular contraction (systole). This phase of the cardiac cycle begins with the appearance of the QRS complex of the ECG, which represents ventricular depolarization. This triggers excitation-contraction coupling, myocyte contraction and a rapid increase in interventricular pressure. Early in this phase, the rate of pressure development becomes maximal. The AV valves to close as interventricular pressure exceed atrial pressure. Ventricular contraction also triggers contraction of the papillary muscles with their attached chordae tendineae that prevent the AV valve leaflets from bulging back into the atria and becoming incompetent. Closure of the AV valves results in the first heart sound (S1). This sound is normally split because mitral valve closure precedes tricuspid closure. During the time period between the closure of the AV valves and the opening of the aortic and pulmonic valves, ventricular pressure rises rapidly without a change in ventricular volume. Ventricular volume does not change because all valves are closed during this phase, therefore, contraction is said to be isovolumic or isovolumetric. Individual myocyte contraction, however, is not necessarily isometric because individual myocyte are undergoing length changes. Individual fibers contract isotonic ally, while others contract isometrical or eccentrically. Therefore, ventricular chamber geometry changes substantially as the heart becomes more spheroid in shape; size increases and atrial base-to-apex length decreases. The rate of pressure increase in the ventricles is determined by the rate of contraction of the muscle fibers, which is determined by mechanisms