The cells of bone their interactions.- Parathyroid hormone and bone.- Vitamin D and bone.- Gonadal hormones and bone.- Thyroid hormones, glucocorticoids, insulin, and bone.- Growth factors and bone.- Prostaglandins and bone.- Cytokines and bone: osteoimmunology.- Chemokines and bone.- Calcium and bone.- FGF-23 and bone and mineral metabolism.- Nervous system mediators and bone.- Genetics of bone disorders.- Osteoporosis pathogenesis.- Structural and metabolic assessment of bone status.- Osteoporosis Therapeutics 2019.- New targets and emergent therapies for osteoporosis.- Drugs causing bone loss.- Natural Products as potential bone therapies.