Final answer:
Osteoblasts secrete collagen to form the organic matrix of bone, onto which hydroxyapatite crystals form, providing bone strength and rigidity.
Step-by-step explanation:
Osteoblasts are specialized bone cells that play a critical role in bone formation. They synthesize and secrete the organic components of the bone matrix, which primarily consist of collagen fibers. Upon this organic matrix, hydroxyapatite crystals are formed when calcium phosphate and calcium carbonate combine, mineralizing the matrix. These crystals provide the rigidity and strength to the bone structure. The process, known as calcification, requires the osteoblasts to control the passage of calcium and phosphate ions, which are essential for crystal formation. As a result, a hard and durable organic-inorganic composite material is produced, which is vital for bone functionality.