Heart Rate Training

Heart Rate Training - Heart Rate Training: Part A:...

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Heart Rate Training: Part A: Electrical signaling and ECG recordings Study Guide This module is designed to help you understand ECG readouts and what it is you are measuring when you do an ECG test. 1. How is cardiac muscle contraction similar to skeletal muscle contraction? Take a look at all the structures that are similar. Like skeletal muscle, cardiac contraction is initiated when extracellular calcium moves into the cell across the voltage dependent L-type calcium channels. The calcium that enters the cell triggers calcium release from the sarcoplasmic reticulum through a process known as calcium triggered calcium release. 2. How does the wave of excitation spread through the heart? The wave of excitation starts at the SA node and then spreads outward through the atria. The wave then funnels through the atrioventricular (AV) bundle by way of the AV node, which acts as a kind of bottleneck due to the relative slowness of impulse conduction in this region. This delay is essential for efficient cardiac function. It allows the wave of excitation to spread completely through the atria before it reaches the ventricles, thus ensuring that atrial contraction is complete before ventricular contraction starts. Once impulses reach the bundle branches and the Purkinje fibers, they are carried relatively quickly to the lower portion of the ventricles. From there the wave of excitation fans through the entire ventricular muscle. 3.
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This test prep was uploaded on 04/19/2008 for the course APK 4125 taught by Professor Drenning during the Spring '08 term at University of Florida.

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Heart Rate Training - Heart Rate Training: Part A:...

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