If a transection is made between the pons and the medulla what will be the effect of respiration
A. Apnea
B. Irregular and gasping
C. No effect
D. Slow and deep
A. Apnea
B. Irregular and gasping
C. No effect
D. Slow and deep
Ans.B. Irregular and gasping
• If the transection is made at the lower end of the medulla, respiration will stop. All the groups of neurons involved in control of respiration are above this level.
• If the transection is made at the upper border of medulla or between pons and medulla, dorsal respiratory group DRG and ventral respiratory group VRG will be retained intact. DRG and VRG project onto the pre-Botzinger pacemaker neurons. Since DRG and pre-Botzinger complex is intact, spontaneous respiration will continue. However, it will be somewhat irregular and gasping. Option b is correct. The reason is that the effect of pontine centers on these medullary neurons will
• If the transection is made at the lower end of the medulla, respiration will stop. All the groups of neurons involved in control of respiration are above this level.
• If the transection is made at the upper border of medulla or between pons and medulla, dorsal respiratory group DRG and ventral respiratory group VRG will be retained intact. DRG and VRG project onto the pre-Botzinger pacemaker neurons. Since DRG and pre-Botzinger complex is intact, spontaneous respiration will continue. However, it will be somewhat irregular and gasping. Option b is correct. The reason is that the effect of pontine centers on these medullary neurons will
be
abolished by such a transection. Pneumotaxic and apneustic center in the pons
influence rate and depth of breathing by modifying the activity of medullary
centers.
• Apneustic center is in the lower pons. Pneumotaxic center is in the upper pons. Pneumotaxic center is said to cause early “switch-off” of inspiratory signal by pacemaker neurons. A transection at lower border of pons and a midpontine section both will remove the pneumotaxic center. However, in midpontine section, apneustic center will remain intact. In a midpontine section, respiration becomes slower and tidal volume greater, and when the vagi are also cut in anesthestized animals, there are prolonged inspiratory spasms—apneusis
• Apneustic center is in the lower pons. Pneumotaxic center is in the upper pons. Pneumotaxic center is said to cause early “switch-off” of inspiratory signal by pacemaker neurons. A transection at lower border of pons and a midpontine section both will remove the pneumotaxic center. However, in midpontine section, apneustic center will remain intact. In a midpontine section, respiration becomes slower and tidal volume greater, and when the vagi are also cut in anesthestized animals, there are prolonged inspiratory spasms—apneusis
