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 causes: September 2009 
Select and explain. 
A. Increase in rate of respiration, B. Increase in depth of respiration, C. Bronchodilation, D. Decreased depth of respiration
D: Decreased depth of respiration
Answer: D: Decreased depth of respiration 
Explanation: Ans. D: Decreased depth of respirationAlthough the rhythmic discharge of medullary neurons concerned with respiration is spontaneous, it is modified by neurons in the pons and afferents in the vagus from receptors in the airways and lungs. An area known as the pneumotaxic center in the medial parabrachial and Kolliker-Fuse nuclei of the dorsolateral pons contains neurons active during inspiration and neurons active during expiration.Stretching of the lungs during inspiration initiates impulses in afferent pulmonary vagal fibers. These impulses inhibit inspiratory discharge.