1 bio212 laboratory 3 the electrocardiogram. 2 objectives for today’s lab acquire a better...
TRANSCRIPT
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Bio212
Laboratory 3
The Electrocardiogram
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Objectives for Today’s Lab• Acquire a better understanding of the theory behind the
ECG
• Record and analyze an ECG• Computers set up in lab
• You will conduct the ECG on a lab partner
• Identify the components of a normal ECG
• Describe the phases of the cardiac cycle represented by each wave form on the ECG
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A GREAT Book on ECGs
This is you after reading the book…confident and no longer intimidated by ECGs!!
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Electrocardiogram
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Time
Mil
livo
lts
PR Interval: 0.12 – 0.20 sec
QT Interval: 0.20 – 0.40 sec
QRS Interval: < 0.10 sec
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The Bipolar Limb Leads
We will be using only Lead II today, so the right arm will be negative, and the foot will be considered positive
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The Electrocardiogram
A wave of the ECG will be positive (up) when the positive wave is moving toward the positive electrode
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Electrocardiogram and Heart Events
Recall that the left foot electrode is POSITIVE, so when the wave of depolarization is moving toward the left foot, we get a positive (up) deflection on the ECG
Right Arm(-)
Left Foot (+)
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Electrocardiogram and Heart Events
Right Arm (-)
Left Foot(+)
Remember that the T-wave represents repolarization of the ventricles.
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ECG Animation…
NYU ECG tutorial site…
This is available on Links to Explore for Lab 3
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The Paper Chart ECG
0.2 sec0.04 sec
Small boxes are usually 1 mm on each side
Ten mm high represents 1 mV
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The Paper ECG Chart
How long is the PR interval on this strip? The QT interval?
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Calculating the Heart Rate
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ECG Parameters
What you will be doing in lab today…
NOTE: This page is reproduced in your Laboratory Study Guide
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What you should do in lab today…
• Read the Background and Introduction in your PowerLab Teaching Experiment handout
• See the “Directions for Use of Laptop Computer” at your station if you laptop is not already turned on
• Set up as described in the demonstration – Use the chart at each ECG station for electrode placement
– Refer to Subject Preparation Steps 4-6 on page 3, if necessary for skin preparation and use of electrode gel
• Run the ECGs for each member of your group by following the Procedure in Exercise 1: ECG in a resting volunteer (page 5)
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What you should do in lab today…
• After EACH member of your group has an ECG recorded, be sure to SAVE the ECG into a file!!!– Select File | Save As (to prevent overwriting
someone else’s file with your data)– Enter a file name using your first and last name
with no spaces as the file name, e.g., SueCidal). – File is saved to the Desktop, so when you retrieve
it later to analyze the data , LOOK ON THE DESKTOP!
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What you should do in lab today…
• After all members of your group have had an ECG recorded…– Analyze your own ECG (use the laptop software)
• Determine the heart rate for your ECG• Examine the PR interval, QRS interval, and QT
interval in your ECG and determine if these are within the normal range
– Complete Part A, C, and D #3-6 and the Critical Thinking Application of your Laboratory Report and hand in with your ECG. Be sure your name is on all the sheets you hand in.
• Before you leave, please delete your ECG file from the Desktop