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08-14-2005, 12:45 PM
Explanation of why the heart can not get tetanus?

08-14-2005, 12:52 PM
Because, the duration of ERP is equal to duration of Mechanical Event.:)

08-14-2005, 12:58 PM
ok, i hate to sound ignorant, but that went over my head. At the moment I am studying basic concepts for my first partial.

08-14-2005, 08:20 PM
Please do read the CVS physiology (Kaplan). I wish I could explain it. But I have my Step 1 exam day after tomorrow...

I will give explanation later..Thanks

08-31-2005, 03:17 AM
If you have Ganong Review of Medical Physiology, look up there, because prof. Ganong has given an excellent scheme showing both electrical and mechanical event one below the other for skeletal muscle and for heart muscle, so by comparing those two schemes you can understand the difference

01-29-2006, 12:01 PM
The action potential in heart muscle is as long as the mechanical event of the heart muscle. Thus, the refractory period in action potential is very long so the heart muscle will not respond to another action potential during a single contraction.

A single action potential causes release of Calcium from the Sarcoplasmic reticulum. Multiple action potentials during a single mechanical event will increase the amount of Calcium released from the sarcoplasmic reticulum and ultimately the interior of the muscle will be saturated with Calcium.

Tetany is caused by multiple action potentials which saturate the interior of the muscle with Calcium and because of this saturation, all the crossbridges which are able to cycle will cycle.

If the muscle does not respond to multiple action potentials during a single mechanical event, then it cannot be tetanized. This is why heart muscle cannot be tetanized.

In skeletal muscle, the action potential is of a very short duration and is much shorter than the duration of the muscle contraction. Thus multiple action potentials can be given to a skeletal muscle during a single mechanical event to which the skeletal muscle will respond and so the skeletal muscle can be tetanized.

01-29-2006, 12:38 PM
Explanation of why the heart can not get tetanus?
Because the heart is where love begins.

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