This MedLibrary.org supplementary page on Tetany (action potential summation) is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
 |
This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (September 2007) |
Tetany is a muscular physical state at which action potentials from nerves arrive to the skeletal muscle motor end plate rapidly enough in succession to cause a steady contraction. This differs from individual twitches in that the twitches are summed. A single twitch may elicit from one action potential at the motor end plate.
Tetany can be demonstrated by applying quick electrical pulses to the skin close to where a nerve lies (such as by the elbow near the ulnar nerve), or the sciatic nerve. If the frequency of charge is once per second, the hand muscles (which the ulnar nerve supplies) will flex once per second. If the frequency is increased, the muscle contractions will sum and appear as one smooth contraction. The hand will smoothly close.
External links
Low serum levels of calcium can produce a condition called tetany. In this case, the skeletal muscle fibers are persistently contracted because they are persistently depolarized, and this is occurring because the serum calcium is very low- without replacement! If serum calcium was low with replacement with another divalent cation, such as Magnesium, then there would not be persistent contraction because Magnesium would competitively inhibit the voltage gated Calcium channels, thereby inhibiting Calcium's entry. However, in Tetany, there is simply low Calcium levels and the cell thinks that it is depolarized and the channels will open.
 |
This medical article is a stub. You can help Wikipedia by expanding it. |
Wikipedia content modification information:
- This page was last modified on 29 January 2008, at 23:32.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Tetany (action potential summation)".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.