Final answer:
Abnormal breathing patterns in upper brainstem lesions (midbrain) result from disruption of the medulla oblongata's DRG and VRG, and the pons' apneustic and pneumotaxic centers. These lesions can lead to disorders like central sleep apnea due to irregular response to carbon dioxide levels.
Step-by-step explanation:
The respiratory pattern observed in the presence of upper brainstem lesions, particularly those affecting the midbrain, are often characterized by abnormal breathing patterns due to the disruption of the normal respiratory centers. These centers, which include the dorsal respiratory group (DRG) and the ventral respiratory group (VRG) in the medulla oblongata, as well as the apneustic and pneumotaxic centers in the pons, play crucial roles in controlling the cycle, depth, and rhythm of breathing.
Under normal circumstances, these centers work together to ensure a consistent, rhythmic breathing cycle, with adjustments made during different physiological conditions like exercise or altitude changes. Damage to the pons or medulla oblongata from conditions such as stroke or congestive heart failure, or from certain pharmacologic agents like morphine, can lead to disorders such as central sleep apnea, where the respiratory rate is irregular or stops for short periods due to a failure in proper response to carbon dioxide levels in the blood.