Q: Blood calcium levels are tightly regulated by the what system?


Read this paragraph and choose the correct option from the provided answers:

Of course, calcium is critical for many other biological processes. It is a second messenger in many signaling pathways, and is essential for muscle contraction, nerve impulse transmission, and blood clotting. Given these roles, it is not surprising that blood calcium levels are tightly regulated by the endocrine system. The organs involved in the regulation are the parathyroid glands.

 Choices:

- digestive

- cardiovascular

- nervous

- endocrine


A:
endocrine