Question

Match List - I with List - II. Volumes and capacities of lungs with their formulas. 

Choose the correct answer from the options given below : 
 

• A. A-I, B-II, C-III, D-IV
• B. A-III, B-IV, C-I, D-II
• C. A-III, B-IV, C-II, D-I
• D. A-II, B-I, C-III, D-IV

Hint:

To memorize basic lung capacities, remember that a 'Capacity' is always the sum of two or more 'Volumes'.
For example: Vital Capacity (VC) = Inspiratory Reserve Volume (IRV) + Tidal Volume (TV) + Expiratory Reserve Volume (ERV).

Answer 1

The Correct Option is C

Step 1: Concept:
The question tests physiological definitions related to respiratory volumes and their corresponding mathematical relationships.

Step 2: Step-by-step Explanation:

• Let us systematically deduce the correct mathematical relations for each parameter.

• A. Alveolar Ventilation: Alveolar ventilation represents the actual volume of fresh air reaching the respiratory zone per minute.
It is calculated by subtracting the anatomical dead space from the tidal volume, and multiplying by the respiratory rate.
Formula: \( (\text{Breathing rate}) \times (\text{Tidal Volume} - \text{Dead Space}) \).
Thus, A matches closely with III.

• B. Total Lung Capacity (TLC): This is the maximum volume of air the lungs can hold after a maximal inhalation.
It is the sum of Vital Capacity (the maximal mobilizable volume) and the Residual Volume (the air left in lungs that cannot be exhaled).
Formula: Vital Capacity + Residual Volume.
Thus, B matches exactly with IV.

• C. Expiratory Reserve Volume (ERV): This is the extra amount of air that can be forcefully exhaled after a normal resting exhalation.
The Functional Residual Capacity (FRC) is the amount of air left in the lungs after a normal breath, encompassing both ERV and RV (\(FRC = ERV + RV\)).
Rearranging this: \(ERV = FRC - RV\).
Thus, C matches exactly with II.

• D. Inspiratory Reserve Volume (IRV): This is the extra air that can be inhaled forcefully after a normal resting inhalation.
Vital Capacity (VC) is the sum of IRV, Tidal Volume (TV), and ERV (\(VC = IRV + TV + ERV\)).
Rearranging for IRV: \(IRV = VC - (TV + ERV)\).
Note: In List-II, statement I says "Vital Capacity - (Tidal Volume + Functional Residual Capacity)". This is a slight misprint in the exam paper. It likely intended to say "Tidal Volume + Expiratory Reserve Volume". Regardless, by the process of elimination of the flawless matches for A, B, and C, D undeniably pairs with I.

• The consolidated correct matching sequence is: A \(\rightarrow\) III, B \(\rightarrow\) IV, C \(\rightarrow\) II, D \(\rightarrow\) I.

Step 3: Final Answer:
The matched sequence clearly aligns with Option (C).