A. one muscle pushes, the other muscle pulls B. fast and slow muscle fibers C. skeletal muscle and smooth muscle D. reciprocal inhibition E. extensors and flexors 8. 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.