Final answer:
During deep inspiration, the ECG may show a taller P wave and a slightly widened QRS complex. During deep expiration, the ECG may show a decrease in the tallness of the P wave and a narrower QRS complex.
Step-by-step explanation:
During deep inspiration (inhaling), there are certain changes in the ECG that can be observed. When the diaphragm contracts and the lungs expand, it leads to an increase in intrathoracic pressure. This results in a decrease in venous return to the heart and a decrease in right atrial pressure. As a result, the P wave on the ECG may become taller and the QRS complex might be slightly widened.
On the other hand, during deep expiration (exhaling), the diaphragm relaxes and the lungs compress. This causes a decrease in intrathoracic pressure. With the decrease in intrathoracic pressure, there is an increase in venous return to the heart and an increase in right atrial pressure. This can lead to a decrease in the tallness of the P wave and a narrower QRS complex on the ECG.