Endocrine System

Question 1

How is calcium levels regulated in the blood?

Answer 1

Calcium levels are regulated by both the thyroid and parathyroid glands.
If calcium levels rise the thyroid gland releases the hormone calcitonin which causes the kidneys to excrete more Ca2+ in urine and reabsorb more into the bone
If calcium levels fall the parathyroid gland secretes the parathyroid hormone. This causes the kidneys to reabsorb more Ca2+ ions, the bone to release more and the digestive system to absorb more. Overall increasing Ca2+ levels and restoring homeostasis.