A. myofilaments B. joints C. ligaments D. tendons E. muscle fibers 9. C. smooth muscle D. cross bridges E. cartilage 10. A. thyroid B. parathyroid C. osteoid D. calcium E. insulin 11. A. Second messengers B. Water soluble hormones C. Lipid hormones D. Local chemical messengers E. Pheromones 12. All muscle cells are contractile. .
Muscles are part of the nervous system. .
Muscles are found in agonistic pairs in which one pulls while the other one pushes. . All muscle cells are excitable. I, IV E. I, II, III, IV 13. A. myofilaments B. cross bridges C. myofibrils D. fibers E. cells 14. The type of cells inside pores in the bone that secrete bone material.