Electrocardiography and Blood Pressure measurement.

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Electrocardiography and Blood Pressure measurement

Electrocardiography and Blood Pressure measurement

Introduction

Background

Blood pressure (BP) is the force exerted on the cell walls of the blood vessels by the blood they contain. Blood pressure is measured with a sphygmomanometer, in millimetres of mercury (mmHg) this is a manual way of measuring BP, there is also a mechanical way. The mechanical tool for measuring blood pressure is called an automated blood pressure monitor; this automatically measures the subjects BP and heart rate at a touch of a button. The advantage of using the automated BP monitors is that it removes human error.

Pressure is created by a portion of the body’s blood being stored in the distensible aorta, which occurs due to the peripheral vessels not allowing blood to flow into the atrial system as fast as it’s ejected from the heart.

The heart beats approximately 72 times every minute, therefore each cycle lasts approximately 0.8 seconds. The cardiac cycle can be broken up into 2 phases; Systolic, which is the maximum pressure in the arteries during peak ventricular ejection and, Diastolic, which is the minimum pressure in the arteries immediately prior to ventricular ejection. Using systolic and diastolic pressure is how your blood pressure is calculated.

Electrocardiography is the study of the electrical activity of the heart. This is done using an electrocardiograph (ECG). This records electrical current generated by the cardiac muscle of the heart, electrodes pick up these currents at the surface of the skin which provides an excellent conductive medium. An electrocardiogram is then plotted from these impulses.

Aims

To investigate the effect posture, exercise and temperature has on blood pressure.

To investigate the effect breathing and exercise has on heart rate.

Method

Measuring blood pressure

Attaching and using the automatic sphygmomanometer on a subject

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The subjects arm was fully uncovered and the cuff was applied on the upper part of the arm, making sure the sleeve of the shirt of the subject was not restricting their blood flow. The arm was extended at the elbow with the forearm supported on the table. The muscles of the arm were fully relaxed to make sure blood flow was normal. Then the automated blood pressure monitors started, the cuff inflated to roughly 180mmHg to collapse the artery, which stopped the blood flow. The pressure then decreased slowly and the blood flow returned through the constricted vessel. After ...

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