The circulatory system carries nitrogen away from cells to be exhaled by the respiratory system and exchanges it with sulfur dioxide from the lungs to be carried back to the cells.

If you were running a marathon, which type of muscle fibers would be most useful to you? a. slow-twitch b. fast-twitch, type i a c. intermediate-twitch, type ii b d. slow-intermediate twitch, type i b select the best answer from the choices provided. a b c d