Variables Affecting Human Arterial Pressure and Pulse Rate

Variables Affecting Human Arterial Pressure and Pulse Rate

When blood pressure is clinically measured, systolic and diastolic values are recorded (Goldring et al., 2014). Systolic arterial pressure is the measurement of pressure when the heart is contracting and the highest figure attained is then used. Diastolic pressure is the measurement of pressure when the heart relaxes. This is characterized by a record of the lowest figure (Bose & Dhanalakshmi, 2012). Pulse pressure is obtained by getting the difference between the diastolic and the systolic pressure readings. The mean arterial pressure (MAP) is then obtained as the average over the cardiac cycle determined by cardiac output (CO), central venous pressure (CVP), and systematic vascular resistance (SVR) (Goldring et al., 2014).

MAP = (CO.SVR) + CVP.

MAP is equivalent to Pdias + 1/3(Psys – Pdias).

Pulse pressure is obtained by through the interaction within the heart’s stroke volume. Pulse pressure is calculated by obtaining the pressure difference of the systolic and diastolic measurements (Bose & Dhanalakshmi, 2012).

Ppulse = Psys – Pdias

For subject 1

Systolic pressure is 118, and 80 diastolic (1st trial)

Pulse pressure is 118 – 80 = 38

Systolic 90, diastolic pressure is 77 (2nd trial)

The pulse pressure is 90 – 77 = 23

MAP 81

Pulse rate 120

For subject 2

Blood Pressure 110/80, Pulse Rate 88, and MAP is 90 (sitting quietly/Baseline)

Blood Pressure 91/69, Pulse Rate 80, and MAP 76 (Reclining/after 2 minutes)

B.P 82/63, P.R 96, and MAP 69 (immediately upon standing)

B.P 102/81, P.R 120, and MAP 88 (After standing for 3 minutes)

Systolic pressure is 90, diastolic pressure is 77

The pulse pressure is 90 – 77 = 23

MAP 81

Pulse rate 120

The cardiovascular system in human beings, consisting of the blood vessels and the heart, responds to exercise with the increase in heart rate as well as the contraction strength with each beat (Goldring et al., 2014). This also results in higher cardiac output and blood pressure. This positive blood pressure is caused by forceful left ventricle contraction measured as systol.  It is then maintained during the relaxation of the ventricle through the aortic valve closure and recoiling of the arteries, measured as diastole (Bose & Dhanalakshmi, 2012). In the experiment upright posture caused an increase in heart rate which was higher than in the baseline position.  Changes in posture are associated with substantial changes in the left ventricle filling and stroke volume (Goldring et al., 2014). Normally, cardiac output is equal to heart rate multiplied by the stroke volume. Cardiac output must be seen to increase in the event of an exercise in order to meet the metabolic needs of the active tissues. According to Bose and Dhanalakshmi, (2012) systolic blood pressure corresponds with the onset of the turbulent flow through arteries and is demonstrated by the first Korotkoff sound, a beating sound that occurs with each heart beat. The average systolic blood pressure value is 120 mmHg. Diastolic blood pressure on the other hand, corresponds with the onset of the laminar flow through the arteries. It is demonstrated by the last Korotkoff sound and its average value is about 80mmHg.

During dynamic exercise results in increase in demand for cardiac output and heart rate, decreased total peripheral resistance, diastolic blood pressure remain the same, and systolic blood pressure increases and then levels off. Static exercise results in need for increased cardiac output, heart rate, total peripheral resistance, and mean arterial pressure (Goldring et al., 2014). From the experiment the diastolic pressure for subject 2 was found to remain almost the same at 80 during the baseline and 81 during the exercise. When subject 2 assumed an upright posture the diastolic pressure also increased. Consequently, during the exercise, the systolic pressure of subject 2 increased from 91 to 102. During the upright posture the MAP increased to 88 from 76 when reclining.

References

Bose, M., & Dhanalakshmi, V. V. (2012). Effect of Short Duration Aerobic Exercises on Resting Blood Pressure and Heart Rate in Pre-hypertensive and Stage 1 Hypertensive Subjects. Indian Journal Of Physiotherapy And Occupational Therapy – An International Journal, (4), 191.

Goldring, N., Wiles, J. D., & Coleman, D. (2014). The effects of isometric wall squat exercise on heart rate and blood pressure in a normotensive population. Journal Of Sports Sciences32(2), 129-136.

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