Plasma potassium (K+) is tightly regulated between?1 pts2.0-3.5 mM3.5-5.0 mM5.0-6.5 mM6.5-8.0 mM

The plasma potassium (K+) levels in the human body are indeed tightly regulated to ensure proper physiological function. Normal plasma potassium levels are crucial for various bodily functions, including nerve impulse transmission, muscle contraction, and overall cell function.

1. Normal Range: The common consensus in medical literature is that normal serum potassium levels range from 3.5 to 5.0 mM. Maintaining these levels within this range is vital, as deviations can lead to serious health issues.

2. Lower Levels: Levels below 3.5 mM can lead to hypokalemia, causing symptoms such as muscle weakness, cramping, and cardiac arrhythmias.

3. Upper Levels: On the other end, levels exceeding 5.0 mM can lead to hyperkalemia, which can be life-threatening as it can cause cardiac problems, including potentially fatal arrhythmias.

In conclusion, the plasma potassium levels are tightly regulated between 3.5-5.0 mM to maintain homeostasis and ensure that the body's cells function properly. Therefore, the correct answer is 3.5-5.0 mM.