Question 33

Parathyroid hormone regulates blood calcium levels.

Parathyroid hormone is the primary hormone responsible for regulating blood calcium levels in the body. It works by increasing calcium absorption in the intestines, reabsorption in the kidneys, and mobilization of calcium from bones.

A) Growth hormone

Growth hormone primarily stimulates growth and cell reproduction, and while it has various effects on metabolism, it does not play a direct role in regulating blood calcium levels. Therefore, this option is incorrect in the context of calcium regulation.

B) Melatonin

Melatonin is a hormone associated with the regulation of sleep-wake cycles and has no significant role in the regulation of blood calcium levels. Thus, this option is also incorrect.

C) Norepinephrine

Norepinephrine is a neurotransmitter and hormone involved in the body’s fight-or-flight response, influencing heart rate and blood pressure. It does not regulate blood calcium levels, making this option incorrect.

D) Parathyroid hormone

Parathyroid hormone is the correct answer as it directly regulates blood calcium levels. It increases the concentration of calcium in the blood by stimulating bone resorption, enhancing intestinal absorption of calcium, and promoting renal tubular reabsorption of calcium.

Conclusion

Parathyroid hormone is definitively the correct answer as it is specifically designed to manage and regulate blood calcium levels, a critical function for maintaining bone health and metabolic processes. In contrast, the other options do not have any significant role in calcium regulation, thereby confirming that they are incorrect choices.