If you shut down the outside of the sodium potassium atpase, the cell becomes more hypotonic. Strength training contracting muscles against resistance (weight training) increases the number of myofilaments in each muscle fiber. 3 major types of muscle fibers: slow oxidative fibers. Contain a type of myosin with relatively low atpase activity but with numerous mitochondria for prolonged regular activity (sometimes called red muscles [red meat leg muscle of chicken]: fast oxidative fibers. Contain a type of myosin with high atpase activity and numerous mitochondria for rapid action (rattle snake tail) Sarcolemma, sacoplasmic reticulum, sarcoplasm, miitochondia and nuclei: multi-nucleus, through the fusion of cells. Myoblasts are immature muscle cells or fibres: how do actin and myosin molecules interact, globular myosin heads bind to actin filaments. The striated appearance (looking like parallel lines) of skeletal muscle is due to: the regular arrangement of filaments. Types of neurons: sensory neurons, gets information from the outside world, motor neuron.