Newsletter

Newsletter

In this Issue

- Frog Electrocardiogram
Experiment
- User Downloads
- Tech Note: Specialized
Recording and
Stimulating Electrodes
- Web Resources
- Special End-of-Year
Product Discounts

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Special Offer

End of Year Discounts on iWorx Electrodes, Transducers, Probes, Signal Conditioners and More

View the complete list of specials
here

The iWorx newsletter is a FREE monthly publication dedicated to sharing teaching laboratory techniques and other useful information with educators in the fields of Anatomy and Physiology. We will also be sending you technical information and info on new developments at iWorx that we feel may be of use to you in your teaching and research activities.

About iWorx
iWorx has everything you need to add excitement and distance learning to any physiology teaching program. Our products include data acquisition hardware, professionally -developed physiology courseware, innovative web tools, and a full selection of transducers, cables, front ends and accessories.

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Dover, NH 03820
P: 800-234-1757
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info@iworx.com

October 2008

Experiment: Frog Electrocardiogram

Unlike a four-chambered mammalian heart, a frog heart has two atria and only one ventricle. Even with one ventricle. the frog heart is able to distribute blood to the lungs and the skin, and the systemic circulation, in the same ventricular contraction. The right side of the ventricle receives blood from the right atrium. This blood, which is coming back to the heart from the tissues of the body, is less oxygenated than the blood in the left atrium. Since the outlet of the right atrium is nearer the outlet of the ventricle, this venous blood enters the arterial trunk first. With the partial separation of the arterial trunk by a spiral valve, most of this blood moves into the pulmocutaneous arteries to the lungs and the skin during ventricular contraction. The left side of the ventricle receives blood from the left atrium. This blood, which is coming back to the heart from the lungs, is more oxygenated than the blood in the right atrium. Since the outlet of the left atrium is farther from the outlet of the ventricle, this blood enters the arterial trunk later and is directed to the systemic and carotid arteries that carry the blood to the body and the head.

Just like the mammalian heart, the frog heart has a set of specialized myocardial cells that function as a pacemaker. These cells are located in the sinus venosus, which is a large vessel that collects blood from the veins and delivers it to the right atrium. The atrial cells contract automatically in a rhythmic manner. The electrical signal from the pacemaker region travels across the sinus venosus causing cells in the sinus to contract. The signal continues to spread like a wave toward the myocardial cells in the adjacent atria. Those cells contract in sequence after the cells in the sinus venosus. From the atria, the electrical signal spreads toward the ventricle causing the contraction of the cells in that chamber. Thus, the repeated, sequential contraction of the parts of the heart moves the blood through the heart, into the large arteries that supply oxygen and nutrients to other organs, muscles, and skin, and back again, continuously. This electrical activity can be recorded and displayed in an electrocardiogram (ECG).

In this laboratory exercise, students will record the effects of temperature on the amplitude and frequency of electrical activity in the heart, as well as the effects of the synaptic transmitters, epinephrine and acetylcholine on these same parameters.

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Download locked Frog ECG experiment.

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Download screen optimized or print optimized Frog ECG experiment.


Download the Updated Settings File for this Month's Experiment with LabScribe2^TM Software
If iWorx users plan to use the Frog ECG experiment in their course, they can obtain a copy of the settings file used to configure the LabScribe2 recording software to do this experiment by clicking here (zip file). To learn how to create your own groups of settings files for use with LabScribe2, click here. The new Settings Manager in LabScribe2 permits numerous pieces of support material to be linked to a settings file and opened automatically when the settings file is selected from the Settings menu. In LabScribe2, animations, illustrations, movies, websites, experimental write-ups, and more can be opened automatically when a settings file is opened.

Tech Note: Specialized Recording and Stimulating Electrodes
Recording biopotential signals from animal tissue may require the use of specialized electrodes. Electrodes that allow tissues or organs, like a heart or a muscle, to move without being restricted by the weight, size, or shape of the electrode may be required. Electrodes designed to reduce damage to tissue while maintaining good conductivity of the signals from the tissue may also be needed. Stimulating electrodes may also need to be specialized to improve conductivity while reducing damage to tissues or organs. View a Tech Note on iWorx specialized recording and stimulating electrodes here.	C-ISO-F3 lead wires with flexible silver wire electrodes C-ISO-N3 lead wires with silver wire electrodes See end-of-year discount offer.

Web Resources
Many articles about electrocardiograms are available on the Internet. Some of the most commonly searched articles can be found on our external Web resources page. On this page we have also accumulated a host of links to informative, external physiology Web sites and conveniently categorized them into major subcategories for easy reference.
Special End-of-Year Discounts
iWorx is offering special discounts on the most popular electrodes, transducers, probes, signal conditioners and more. View the complete list of discounted products, prices and related experiments here. Offer ends December 31, 2008.