**Question:** All of the following statements are true about Pneumotaxic Centre except

A. The Pneumotaxic Centre is located in the medulla oblongata.
B. The Pneumotaxic Centre controls the breathing rate.
C. The Pneumotaxic Centre is part of the respiratory reflex arc.
D. The Pneumotaxic Centre is located in the spinal cord.

**Core Concept:**
The Pneumotaxic Centre is a critical part of the respiratory system, particularly in the regulation of breathing rate and depth. It is involved in the respiratory reflex arc, which is a series of interconnected neurons that respond to changes in the partial pressure of oxygen and carbon dioxide (CO2) in the blood. The Pneumotaxic Centre receives information about CO2 levels and sends signals to the appropriate areas to regulate breathing accordingly.

**Why the Correct Answer is Right:**
The Pneumotaxic Centre is indeed located in the medulla oblongata, a region of the brain responsible for vital functions like breathing, heart rate, and blood pressure regulation. While it plays a significant role in controlling the breathing rate, the statement that claims it is located in the spinal cord is incorrect. The spinal cord is responsible for reflexes and motor control but does not house the Pneumotaxic Centre.

**Why Each Wrong Option is Incorrect:**
Option A is incorrect because the Pneumotaxic Centre is located in the medulla oblongata, not the spinal cord. The medulla oblongata is part of the brainstem and contains the respiratory control centers, including the Pneumotaxic Centre.

Option B is incorrect as the Pneumotaxic Centre is responsible for regulating breathing rate, not controlling it directly. Its role is to send signals to the appropriate areas in the brainstem and spinal cord, which in turn control the respiratory rate.

Option C is accurate as the Pneumotaxic Centre is part of the respiratory reflex arc, which involves various centers and neurons in the brainstem and spinal cord. However, it is not the entire respiratory reflex arc.

**Clinical Pearl:**
The Pneumotaxic Centre plays a crucial role in maintaining the balance between ventilation and CO2 levels in the bloodstream. When CO2 levels increase, the Pneumotaxic Centre stimulates the medulla oblongata and spinal cord to facilitate increased ventilation. Conversely, when CO2 levels decrease, it inhibits these centers to reduce ventilation. This mechanism helps maintain a stable CO2 level in the blood, ensuring adequate gas exchange in the lungs. Understanding the location and function of the Pneumotaxic Centre is essential for understanding respiratory control and maintaining homeostasis in the body.