Includes Teacher's Notes and Typical Experiment Results Instruction Manual and Experiment Guide for the PASCO scientific Model CI-6539A 012-06852A 11/98 EKG SENSOR EK Ele ctr od es R E B F LK -G R N + R E D G A 39 65 T ENS EMDE O. ACRO T N PLCT AR T RE E P R ELCO 0 EN FOKG AS 5-02AL E E P 53UIV US EQ R O CI- G R M) EKSOIOGRA NARD C O SE TR C LE (E © 1998 PASCO scientific $5.
012–06852A EKG Sensor Table of Contents Section Page Copyright, Warranty, and Equipment Return ........................................................................ ii Introduction .............................................................................................................................. 1 Equipment ................................................................................................................................. 1 Theory ..............................................
Copyright, Warranty, and Equipment Return Please—Feel free to duplicate this manual subject to the copyright restrictions below. Copyright Notice The PASCO scientific 012-06852A EKG Sensor manual is copyrighted and all rights reserved. However, permission is granted to non-profit educational institutions for reproduction of any part of the manual providing the reproductions are used only for their laboratories and are not sold for profit.
012–06852A EKG Sensor Introduction The PASCO CI-6539A EKG (Electrocardiogram) Sensor measures cardiac electrical potential wave forms (voltages produced by the heart as its chambers contract). The sensor is designed for use with a PASCO computer interface as an educational aid; it is not intended for medical diagnosis. This sensor complements the PASCO CI-6535 Respiration Rate Sensor.
EKG Sensor 012–06852A Theory Heart muscle cells are polarized at rest. This means the cells have slightly unequal concentrations of ions across their cell membranes. See Figure 1. An excess of positive sodium ions on the outside of the membrane causes the outside of the membrane to have a positive charge relative to the inside of the membrane. The inside of the cell is at a potential that is about 90 millivolts (mV) less than the outside of the cell membrane.
012–06852A EKG Sensor simultaneously. This process causes a small time delay and so there is a short pause after the atria contract before the ventricles contract. Because the cells of the heart muscle are interconnected, this wave of depolarization, contraction and repolarization spreads across all the connected muscle of the heart. See Figure 2.
EKG Sensor The Electrocardiogram One part of a typical EKG (electrocardiogram) is a ‘flat line’ or trace indicating no detectable electrical activity. This line is called the Isoelectric line. Deviation from this line indicates electrical activity of the heart muscles. The first deviation from the Isoelectric line in a typical EKG is an upward pulse followed by a return to the Isoelectric line. This is called the P wave and it lasts about 0.04 seconds.
012–06852A The sequence from P wave to T wave represents one heart cycle. The number of such cycles in a minute is called the heart rate and is typically 70-80 cycles (beats) per minute at rest. Some typical times for portions of the EKG are given in Figure 3. P-R interval ....120-200 milliseconds QRS interval ....under 100 milliseconds Q-T interval .....
EKG Sensor 012–06852A Setup Connecting the EKG Sensor to a Person Use three electrode patches per subject. The electrodes can be reused but they tend to absorb moisture (they are very hygroscopic), and therefore, reuse is not recommended. • Because the electrical signal produced by the heart and detected at the body’s surface is so small, it is very important that the electrode patch makes good contact with the skin.
012–06852A EKG Sensor Using the EKG Sensor with Science Workshop™ Interfaces The reading from the EKG Sensor in the Science Workshop software has been scaled to the millivolt range. The reading is adjusted so that zero volts represents the Isoelectric line. 1. Connect the EKG Sensor unit to analog channel A, B, or C of the Science Workshop computer interface box using the cable with the DIN connectors (Figure 7). Alternatively, the unit can be plugged directly into the analog channel jack.
EKG Sensor 012–06852A Suggested Experiments Resting EKG • Measure the EKG of a person who is at rest. The person whose EKG is being measured should remain calm and relaxed. Encourage the person to breath normally. Use the Graph to display the recorded data. • Record the information specified in Table 1.1: • Compare your values to the ones given earlier. What could explain the differences? EKG after Mild Exercise • Measure the EKG of a person who is initially at rest.
012–06852A EKG Sensor Technical Support Feedback Contacting Technical Support If you have any comments about the product or manual, please let us know. If you have any suggestions on alternate experiments or find a problem in the manual, please tell us. PASCO appreciates any customer feedback. Your input helps us evaluate and improve our product.
