Biological role of Na, K, Mg, Ca
s-Block Elements · Chemistry
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Why does low blood K⁺ (hypokalemia) cause muscle weakness and heart arrhythmia? Step 1: Resting membrane potential depends on the K⁺ gradient (high inside, low outside). Step 2: Low blood K⁺ steepens the gradient → membrane hyperpolarises. Step 3: Hyperpolarised cells are harder to excite → muscles weaken. Step 4: Heart pacemaker cells misfire → arrhythmia. Tiny ion shifts, huge effects!