<prompt> Which of the following physiological change can occur when there is vagal stimulation of hea?Increased R-R intervalIncreased hea rateIncreased cardiac outputIncreased force of contraction  <response>: Stimulation of parasympathetic vagus fibers causes decrease in the hea rate increased R-R interval, reduce the force of contraction, and constrict the coronary aeries. Stimulation of sympathetic nerves increases hea rate decreased RR interval. Ref: Moon D.A., Foreman K.B., Albeine K.H. 2011. Chapter 4. Hea. In D.A. Moon, K.B. Foreman, K.H. Albeine Eds, The Big Picture: Gross Anatomy. 