ABGs have a way of making smart nursing students freeze, not because they’re impossible, but because they’re often taught like a memorization game. We’re flipping that. Once you see arterial blood gases as relationships between pH, PaCO2, and HCO3, the confusion drops fast and the questions start to feel predictable. We walk through the exact ranges you need for nursing school and the NCLEX, then lock in the rule that keeps everything straight: CO2 is respiratory and bicarbonate (HCO3) is me...