- Ringer's solution contains nutrients and ions that are required
for the heart to continue functioning. If we didn't do this,
it would die.
- Some of the recovery is due to the action of the heart.
Since the SA node controls heart rate, it is capable of returning to
normal levels on its own. In addition, the fact that we are
constantly bathing the heart in Ringer's solution means that the
chemicals that are affecting the heart will be gradually washed out.
- Stimulation of the vagus nerve slows heart rate. Continued
stimulation of this nerve can actually stop the heart
entirely. The heart rapidly stops paying attention to the
vagus nerve if such stimulation would lead to the heart stopping for
excessive parts of time.
- You needed to apply the stimulus during the ventricular phase,
during diastole.
- During a tetanic contraction, a muscle contracts to its shortest
length and holds in place. If the heart were able to do this,
once it contracted, it would be capable of getting "stuck"
meaning that it could no longer pump blood. Since this would
be rapidly fatal, most people would prefer that this not happen!
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