Which of the following is part of the axial skeleton?

A. Oxygen transport:Oxygen transport is performed by blood (hemoglobin in red blood cells) rather than the integumentary system.
B. Temperature regulation:The integumentary system helps regulate body temperature through sweat production and cutaneous blood flow adjustments.
C. Nutrient absorption:Nutrient absorption primarily occurs in the gastrointestinal tract, not the skin (with the exception of limited topical absorption).
D. Hormone secretion:The skin contributes to endocrine activity by synthesizing vitamin D precursors, but widespread hormone secretion is not its main function.

A. Fibrocartilaginous callus formation:Fibrocartilaginous callus formation is an early reparative stage that follows hematoma organization, helping bridge the fracture but does not occur first.
B. Formation of a bony callus:Formation of a bony (ossified) callus occurs after the fibrocartilaginous callus is replaced by woven bone during repair.
C. Hematoma formation:Hematoma formation occurs immediately after the fracture as blood vessels rupture, creating a clot that initiates inflammation and brings cells needed for healing.
D. Remodeling of bone:Remodeling is the final phase in which woven bone is replaced by lamellar bone and the medullary canal is restored; it occurs well after initial healing.