This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Vagal stimulation of the hea causes: 
Select and explain. 
A. Increased hea rate, B. Increased R-R interval in ECG, C. Increased force of hea contraction, D. Increased cardiac output
B: Increased R-R interval in ECG
Answer: B: Increased R-R interval in ECG 
Explanation: Increased R-R interval in ECG Vagus is the parasympathetic supply to the hea. Its stimulation causes: - Decreased hea rate - Decreased force of hea contraction - Decreased cardiac output R-R interval is the time interval between consecutive hea beats in the electrocardiogram. So a decrease in hea rate increases the R-R interval Reverse effects on the hea are noted due to sympathetic stimulation.