Biology

Electrocardiogram & Peripheral Circulation

The heart is a dual pump that pushes blood around the body and through the lungs. The beating of the heart results in a blood flow that is itself rhythmic. In this lab you will measure the flow of blood through the finger of a student volunteer and correlate it with the ECG. In addition you will palpate various arteries, and look at peripheral circulation.

Written by staff of ADInstruments.

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Background

The arterial system functions as a pressure reservoir. Blood leaves the arterial system continuously through the capillaries, but enters intermittently from the heart. The ventricles contract during systole; the semilunar valves open and blood flows into the arterial system. At this point the arteries expand and the blood pressure increases. Systolic pressure is the peak pressure value. The relaxation of the ventricles is called diastole. During diastole, the ventricles fill with blood from the atria and veins, and prepare for the next systole. Simultaneously, blood flows out of the arterial system through the capillaries and the arterial pressure decreases. When the arterial blood pressure is at its lowest — immediately before the contracting ventricle pushes blood into the arteries — this value is called the diastolic pressure. Although the variation in arterial blood pressure during the cardiac cycle is smoothed out by the inherent elasticity of the major arteries, blood still exhibits pulsatile flow through the arteries and arterioles.

Required Equipment

A computer system

Chart software, version 5.0 or higher

PowerLab (with built-in Bio Amp or PowerLab and Bio Amp front-end)

Five-lead Shielded Bio Amp Cable, & snap-connect Lead Wires

Reusable clamp electrodes or disposable adhesive electrodes

Electrode cream (for use with the clamp electrodes)

Alcohol swabs (70% ethanol on cotton wool or paper tissue); optional

Ballpoint pen

Abrasive pads/gel

Finger Pulse Transducer

Procedures

A. Set up and...