EKG Probe

Authors: Laurie Aiello, Tom Schuster, Craig Didden
Probeware / Instrumentation
SED 695B; Fall 2005

Research Question:
What are the effects of various body positions and food items on the electrical impulses of the heart as recorded by an EKG probe.




Standards addressed:
Structure and Function
5. b
. Students know organ systems function because of the contributions of individual organs, tissues, and cells. The failure of any part can affect the entire system.
Physical Principles
6. j. Students know that contractions of the heart generate blood pressure and that heart valves prevent back flow of blood in the circulatory system.

9. a. Students know how the complementary activity of major body systems provides cells with oxygen and nutrients and removes toxic waste products such as carbon dioxide.
9. b. Students know how the nervous system mediates communication between different parts of the body and the body's interactions with the environment.

Independent Variable _Dependent Variables

___Time in Seconds ___________Voltage of the _____________________________Myofibers
____________________________of the Heart

Resting with
Normal Diet
  • Standing
  • Lying
  • Running in Place
  • Consumption of Ca ("Tums")
  • Consumption of Caffeine ("Red Bull")
  • Consumption of Potassium (bananas)
  • Computer with Windows 2000, Windows XP.
    or Mac OS X
  • EKG Sensor from Pasco
  • USB Link from Pasco
  • "Data Studio" from Pasco
  • "Tums" Antacid Tablets with Calcium
  • "Red Bull" Energy Drink
  • Bananas

Electrode Placement

Record EKG under the following conditions:

  • Sitting
  • Standing
  • Running in place
  • After consumption of calcium
  • After consumption of caffeine
  • After consumption of potassium
The EKG Probeware gives a graph of the electrical conduction through the heart. Students can record the electrocardiograph on the computer.

This sample table demonstrates how students can measure and record the heart beats per minute, height (in voltage) and time (in seconds) of P waves, T waves, and the QRS complex for their chosen investigation. Each team can do a resting measurement and then compare that to various positions and consumption of food items.

Sample Data Tables

The class can then compare their EKG data with the other team investigations and draw conclusions.

Data Studio allows the students to collect EKG data.

They can measure their heart rates and the voltages of the:

  • P wave - which represents depolarization of the atria.
  • QRS wave - which is depolarization of the ventricles (repolarization of the atria is masked by this wave).
  • T wave - which represents repolarization of the ventricles.
Data Studio also allows students to record a second EKG over the first. This allows for easy comparison at a glance. Here the red tracing is at rest and the blue is after running in place.
There is also a "Smart Tool" which allows the students to quickly measure the interval from peak to peak and calculate the heart rate. Students can also calculate the amount of voltage difference between the two tracings.

Here is a sample data table with sample data.

A comparison can be made between the student's resting EKG and after running in place. Notice that the voltage for each wave has not changed, but the time for each wave has decreased.

The same student could then rest and lay down, or eat a food containing something that may affect the EKG.

This link from MCDB at the University of Colorado at Boulder will show the electrical impulse transmission through the sinoatrial node, atrial ventricular node, Bundle of His and the Purkinje fibers of the heart along with the EKG read out.

This video clip also shows another view of the electrical impulses of a beating heart. Illustration of the impulse from the sinoatrial node in the right atrium to the atrial ventricular node, down the Bundle of His to the Purkinje fibers of the ventricles.
MCDB at the University of Colorado at Boulder

This animation from MCDB at the University of Colorado at Boulder shows the blood flow through a beating heart.

References & Links:

Pasco Probeware

Molecular Cellular and Developmental Biology at the University of Colorado at Boulder