The medulla oblongata contains which of the following areas? 1. Apneustic center 2. Dorsal respiratory group neurons (DRGs) 3. Pneumotaxic center 4. Ventral respiratory group neurons (VRGs)

a. 1, 2, and 3 only
b. 2 and 4 only
c. 3 only
d. 1, 3, and 4 only

ANS: B
Instead, the medulla contains several widely dispersed respiratory-related neurons, as shown in Figure 15-1. The DRGs contain mainly inspiratory neurons, whereas the VRGs contain both in-spiratory and expiratory neurons.