ECG-HeartSounds-LS2.pdf - Experiment HH-2 The Electrocardiogram and Heart Sounds Background Blood enters the arterial system from the ventricles of the

ECG-HeartSounds-LS2.pdf - Experiment HH-2 The...

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Human Heart HH-2-1 Experiment HH-2: The Electrocardiogram and Heart Sounds Background Blood enters the arterial system from the ventricles of the heart in a pulsatile manner. However, when blood is leaving the arterial system through the capillaries, it flows in a continuous manner. Between contractions, when the heart is relaxed and blood is not being pumped into the arterial system, there is still enough pressure in the arterial system to move blood along the arteries. The pressure in the arterial system exists because the elasticity of the arteries allow them to distend and recoil and function as a pressure reservoir. When the ventricles contract, the pressure of the blood inside the ventricles increases to close the atrioven- tricular valves. Further contraction increases the ventricular pressure until it exceeds the arterial pressure. At this point, when the arterial pressure is at its lowest point during the cardiac cycle (called diastolic pressure) the semilunar valves are forced open, and blood flows into the artery. Blood entering the arterial system inflates the arteries a little and increases blood pressure to a maximum, which is the systolic pressure. In this lab you will record the ECG from a subject and listen to the characteristic “lub-dub” heart sounds. The “lub” sound occurs during the early phase of ventricular contraction and is produced by closing of the atrioven- tricular valves, which prevents blood flow into the atria. When the ventricles relax, the blood pressure drops below what is in the artery and the semilunar valves close, producing the “dub” sound. Equipment Required PC Computer IWX/214 data acquisition unit USB cable IWX/214 power supply C-AAMI-504 ECG cable and electrode lead wires EM-100 Event marker Stethoscope Alcohol swabs Disposable ECG electrodes IWX/214 Setup 1 Place the IWX/214 on the bench, close to the computer. 2 Check Figure T-1-1 in the Tutorial Chapter for the location of the USB port and the power socket on the IWX/214. 3 Check Figure T-1-2 in the Tutorial Chapter for a picture of the IWX/214 power supply. 4 Use the USB cable to connect the computer to the USB port on the rear panel of the IWX/214. 5 Plug the power supply for the IWX/214 into the electrical outlet. Insert the plug on the end of the power supply cable into the labeled socket on the rear of the IWX/214. Use the power switch to turn on the unit. Confirm that the red power light is on. Start the Software 1 Click on the LabScribe shortcut on the computer’s desktop to open the program. If a shortcut is not available, click on the Windows Start menu , move the cursor to All Programs and then to the listing for iWorx . Select LabScribe from the iWorx submenu . The LabScribe Main window will appear as the program opens.
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