Physiology 2130 Study Guide - Final Guide: Hyperkalemic Periodic Paralysis, Hyperkalemia, Electrochemical Gradient
23 Dec 2015
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About 10 minutes after leaving the field, timmy became so weak that he could not stand for about 30 minutes. Questioning revealed that he had complained of weakness after eating bananas, had frequent muscle spasms, and occasionally had myotonia (prolonged contraction of skeletal muscles). After a thorough physical examination, timmy was diagnosed with the rare disease hyperkalemic periodic paralysis, a condition that prevents the proper closing of the na+ channel activation gate. Attacks can lead to muscle weakness or paralysis if not treated. Question #1: describe how the cell membrane repolarizes during an action potential. To start the repolarization phase (at ~+30mv), na+ channels close their inactivation gate and k+ channels open. This causes an out-flux of k+ ions out of the cell, and na+ ions can no longer move inside the cell, thus causing the cell to become more and more negatively charged. 70mv when the na+ channel inactivation gate opens again, but the activation gate closes.
