Which of the following represents inspiratory capacity ?

Options

A. IRV
B. IRV +TV
C. IRV+ERV+TV
D. IRV+ERV+TV+RV

Answer

To determine which option represents inspiratory capacity, we need to understand the components that make up this capacity.

### Step-by-Step Solution:

1. **Understand the Definition of Inspiratory Capacity**:
Inspiratory capacity (IC) is defined as the maximum amount of air that can be inhaled after a normal expiration. It is the sum of two volumes: tidal volume (TV) and inspiratory reserve volume (IRV).

2. **Identify Tidal Volume (TV)**:
Tidal volume is the amount of air inhaled or exhaled during normal breathing. The typical value for tidal volume is approximately 500 ml.

3. **Identify Inspiratory Reserve Volume (IRV)**:
Inspiratory reserve volume is the additional air that can be inhaled after a normal inhalation. The typical value for IRV is around 2500 to 3000 ml (or 2.5 to 3 liters).

4. **Calculate Inspiratory Capacity**:
To find the inspiratory capacity, we add the tidal volume and the inspiratory reserve volume:
\[ \text{Inspiratory Capacity (IC)} = \text{Tidal Volume (TV)} + \text{Inspiratory Reserve Volume (IRV)} \]
Substituting the values:
\[ IC = 500 \, \text{ml} + 2500 \, \text{ml} \text{ (approximately)} \]
\[ IC \approx 3000 \, \text{ml} \text{ to } 3500 \, \text{ml} \]

5. **Select the Correct Option**:
Based on the calculated inspiratory capacity of approximately 4000 to 4500 ml (considering the higher end of IRV), we can now look at the options provided and select the one that matches this value.

### Conclusion:
From the explanation, the correct representation of inspiratory capacity is the sum of tidal volume and inspiratory reserve volume, which results in a value around 4000 to 4500 ml. Thus, the correct answer is option B.

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