Mark the incorrect statement

Options

A. Hering Breure's reflex prevents the over expansion of lungs
B. Oxygen dissociation curve for foetal haemoglobin is on the left side with respect of maternal haemoglobin
C. When pneumotaxic centre transmits strong signals the inspiration time becomes shorter
D. Amount of air left in the lung after normal expiration is termed as residual volume only

Answer

To solve the question "Mark the incorrect statement," we need to analyze each of the provided statements carefully.

### Step-by-Step Solution:

1. **Statement A: Herring-Breuer reflex prevents the over-expansion of lungs.**
- This statement is correct. The Herring-Breuer reflex is a protective mechanism that prevents over-inflation of the lungs during deep breathing.

2. **Statement B: Oxygen dissociation curve for fetal hemoglobin is on the left side with respect to maternal hemoglobin.**
- This statement is also correct. Fetal hemoglobin has a higher affinity for oxygen compared to maternal hemoglobin, which allows it to effectively extract oxygen from the mother's blood.

3. **Statement C: When pneumotoxic center transmits strong signals, the inspiration times become shorter.**
- This statement is correct as well. The pneumotoxic center, located in the pons of the brain, regulates the rate and pattern of breathing. Strong signals from this center can lead to shorter inspiration times.

4. **Statement D: Amount of air left in the lungs after normal expiration is termed as residual volume.**
- This statement is incorrect. The amount of air left in the lungs after normal expiration is not solely referred to as residual volume. Instead, it includes both the expiratory reserve volume and the residual volume. Residual volume specifically refers to the air remaining in the lungs after a forceful expiration.

### Conclusion:
The incorrect statement among the options provided is **Statement D**.