What is NOT a function of the skeletal system?

Hormonal regulation is not a function of the skeletal system. The primary functions of the skeletal system include providing structure and support to the body, facilitating movement by acting as levers for muscles, protecting vital organs such as the heart and lungs, and producing red blood cells in the bone marrow.

While bones do interact with hormones, particularly in the regulation of calcium and phosphate levels, the direct production or regulation of hormones is not a primary role of the skeletal system itself. The other options clearly denote essential roles that the skeletal system plays in maintaining overall body function and health.