Final answer:
Hypercalcemia is the condition that causes increased neuromuscular irritability which can progress to seizure activity. It is characterized by abnormally high levels of calcium. The effects of hypercalcemia include lethargy, constipation, confusion, and in severe cases, coma.
Step-by-step explanation:
Hypercalcemia, a condition characterized by abnormally high levels of calcium, causes increased neuromuscular irritability which can progress to seizure activity. In hypercalcemia, the nervous system is underactive, resulting in lethargy, constipation, confusion, and in severe cases, coma. Increased calcium levels can affect membrane permeability and decrease the responsiveness of the nervous system.