Cardiovascular response to changes in body position and physical activity
The aims of the experiment were to investigate the cardiovascular responses to changes in body position and exercise on human blood pressure using an electronic (automated) blood pressure meter. Moreover, monitoring changes in blood flow and blood pressure in the body while sitting, lying supine, standing, as well as engaging in low intensity exercise of walking and medium intensity exercise of squatting after 2 minutes. The main conclusions of the experiment were that systolic blood pressure, mean arterial blood pressure, and pulse rate increase during levels of physical activity compared to the measurements read at the initial resting positions, whereas the diastolic blood pressure remained fairly constant throughout the different measurement readings.
The blood that circulates throughout the body maintains a flow and pressure. Blood pressure is the force of blood against a blood vessel wall. Blood pressure is needed to push the blood along the blood vessels to reach the various tissues of the body (5). The nervous system can change the flow and pressure based on the particular needs at a given time, such as during exercise where blood pressure and blood flow is increased (6). In the systemic heart, blood starts in the heart and is pumped from the left ventricle through the aorta to the tissue beds of the body. The blood then returns to the heart from the body through the systemic veins. It returns to the right atrium, and is pumped to the right ventricle. From the right ventricle the blood is pumped through the pulmonary arteries to the lungs, where gas exchange occurs. The blood is returned to the heart through the pulmonary veins to the left atrium. Then it is pumped to the left ventricle to complete the circuit (1, 2).
The pressure at which the heart pumps blood throughout the body must be able to overcome the resistance in the circulatory system (3). In order to accommodate this, the blood vessels work to even out the pressure gradient inherent with each beat of the heart, and consequently this makes the blood flow steady (2). As the heart beats and forces blood into the systematic vessels, they expand to accommodate the pulse of blood during systolic pressure and contract during diastolic pressure to supply the body with a constant blood flow (2). They expand and contract in a rhythm out of phase with the heart beats to regulate the pressure to create a constant blood flow to the body (2).
The cardiac cycle involves increasing aortic blood pressure above the veins, causing blood flow through the systemic circulation (1). Blood flow through the pulmonary circulation is caused by higher pressure in the pulmonary arteries than in the pulmonary veins (1). Systolic blood pressure, the maximum blood pressure, arises when the heart contracts, pumping blood into the aorta (systole) (2). Diastolic blood pressure, minimum blood pressure level, in which the ventricles relax causes arterial pressure to decrease resulting in the heart refilling with blood (diastole) (2). Another derived measurement is the mean arterial pressure (MAP), which is the average blood pressure in the arteries throughout the cardiac cycle and can be calculated by taking into account the diastolic and systolic blood pressures. It is calculated from the amount or rate of blood pumped into circulation by the heart, which is derived as the cardiac output, and the sum of the resistance of all systemic blood vessels is equal to the total vascular resistance (1). Mean arterial pressure is an important diagnostic measurement in identifying chronic hypertension (2). High blood pressure puts a greater workload on the heart and has been correlated with an increased risk for many diseases including stroke, heart attack, cardiovascular disease, and kidney failure (5)
The main aims of this experiment were to compare the different measurements of blood...
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