Final answer:
Hypocalcemia, which is caused by abnormally low levels of blood calcium, leads to excessive excitability of the nervous and muscular systems with symptoms that may include muscle twitching and severe cramps. It is often treated effectively with a good prognosis.
Step-by-step explanation:
The condition characterized by excessive excitability of the nervous and muscular systems due to low blood calcium levels is Hypocalcemia (B). Hypocalcemia can lead to increased membrane permeability to sodium, resulting in symptoms such as muscle twitching, cramping, spasms, or convulsions. Severe cases of hypocalcemia may lead to muscle paralysis, including those involved in breathing, and can be life-threatening.
Various factors can cause hypocalcemia, including hypoparathyroidism, which can occur after injury or surgery to the thyroid gland. Symptoms are generally due to the critical role calcium plays in cellular functions, including muscle contraction and nerve impulse transmission. The treatment for hypocalcemia varies depending on the underlying cause, but it is typically managed with good prognoses when addressed promptly.