Final answer:
The alveolar ventilation rate is true as the best index of effective ventilation because it reflects the volume of air available for gas exchange in the alveoli, important for maintaining appropriate oxygen and carbon dioxide levels in the blood.
Step-by-step explanation:
The statement 'The alveolar ventilation rate is the best index of effective ventilation' is true. Alveolar ventilation rate is a measure of the air that reaches the alveoli per minute and is vital for effective gas exchange in the lungs. It is calculated by subtracting the volume of air that remains in the conducting airway (anatomic dead space) from the tidal volume (the air volume per breath), and then multiplying by the respiratory rate. Effective alveolar ventilation maintains appropriate oxygen and carbon dioxide levels in the blood, avoiding hypoxemia and hypercapnia.
There are compensatory mechanisms in the respiratory system to maintain alveolar ventilation. When alveolar ventilation is deemed too low, a condition known as hypoventilation, the body can respond by increasing the respiratory rate and typically also increasing the tidal volume to satisfy oxygen demand. Conversely, if alveolar ventilation is too high, leading to hyperventilation, the respiratory rate can increase while the tidal volume decreases to avoid excessive loss of carbon dioxide.
In summary, alveolar ventilation rate is indeed a crucial index for the effectiveness of lung ventilation because it directly reflects the amount of air that participates in gas exchange, which is essential for maintaining proper physiological function.