Essay --

The cardiac cycle is equilibrium to one complete heartbeat, first the atria contracts and then ventricles contract and then relax. This can be marked by the many changes in blood volume and pressure within the heart. While the heart is in complete relaxation (diastole) the pressure in the heart is very low, blood is flowing from the pulmonary and systemic circulations into the atria and on through to the ventricles; the semilunar valves are closed and the AV valves are open (Pearson, 475). Not long after atrial contraction occurs and atrial pressure increases, forcing residual blood into ventricles, then ventricular systole begins and intraventricular pressure increases swiftly, closing the AV valves. The ventricular pressure surpassed when this happens the semilunar valves are forced open, and the blood in the ventricular chambers is dispersed through the valves. In the course of this phase the aortic pressure reaches approximately 120mmHg in a healthy young adult. During ventricula r systole the atria relax and their chambers fill with blood, resulting in a gradual increase in atrial pressure (Martini, 684). At the end of ventricular systole, the ventricles relax: the semilunar valves closes shut (preventing backflow), and momentarily, the ventricles are closed chambers. The aortic semilunar valve snaps shut causing a quick increase in the aortic pressure, results from the elastic recoil of the aorta after the valve closes. As the ventricles relax, the pressure within them begins to drop. The average heart beats approximately 75 beats per minute, the length of the cardiac cycle is about 0.8 second (Martini,). There are sounds heard in the cardiovascular system result from turbulent blood flow. There are two unmistakable sounds ... ...ds have disappeared the diastolic pressure is recorded. After the data is collected you must then calculate your numbers to get your mean arterial pressure (MAP) using the formula two-thirds diastolic plus one-third systolic (MAP=2/3 diastolic + 1/3 systolic). Checking my pulse before and after light exercise I was able to obtain my cardiac output using the formula heart rate times stroke volume (CO=HR(SV)) because stroke volume varies with gender as well as body type professor Raj provides us with those numbers. After those numbers were calculated we were then able to measure the total peripheral resistance (TPR) using what information we already had using the formula MAP/CO. In the data that follows you will see the average for a group of 25 people for each mean arterial pressure, cardiac output, and total peripheral resistance before and after the light exercise.