Final answer:
The student nurse experiencing respiratory alkalosis due to hyperventilation during surgery results in increased protein-binding of ionized calcium, causing tetany. A decrease in ionized calcium is responsible for the symptoms of stiffness and numbness. Proper calcium balance is crucial for maintaining neuro-muscular function.
Step-by-step explanation:
The student nurse experiencing hyperventilation in surgery, which led to respiratory alkalosis, caused increased protein-binding of ionized calcium. This resulted in a condition called tetany, which manifests with symptoms such as stiffening of the extremities and numbness and tingling of the hands. The shift in the blood's pH due to alkalosis increases the affinity of calcium to bind to serum proteins, thereby decreasing the ionized (free) calcium concentration. It is the decrease in ionized calcium that leads to increased neuromuscular excitability and the tetanic symptoms observed.
Tetany can also arise from conditions such as hypoparathyroidism, which is characterized by insufficient production of parathyroid hormone (PTH), leading to hypocalcemia. Conversely, hypercalcemia represents a condition with abnormally high levels of calcium, which can cause a depressed nervous system. This clarifies the critical role of calcium homeostasis in neuro-muscular function and systemic physiology.