If in a person functional residual capacity (FRC) is 2300 ml, residual volume (RV) is 1200 ml and inspiratory capacity (IC) is 3500 ml then find out its vital capacity (VC)-

Options

A. 5800 ml
B. 7000 ml
C. 4600 ml
D. 2300 ml

Answer

To find the vital capacity (VC) given the functional residual capacity (FRC), residual volume (RV), and inspiratory capacity (IC), we can follow these steps:

### Step 1: Understand the Definitions
- **Functional Residual Capacity (FRC)**: This is the volume of air remaining in the lungs after a normal expiration. It is the sum of the Expiratory Reserve Volume (ERV) and the Residual Volume (RV).

\[ FRC = ERV + RV \]

- **Residual Volume (RV)**: This is the volume of air that remains in the lungs after a maximal exhalation.

- **Inspiratory Capacity (IC)**: This is the maximum amount of air that can be inhaled after a normal expiration. It is the sum of Tidal Volume (TV) and Inspiratory Reserve Volume (IRV).

\[ IC = TV + IRV \]

- **Vital Capacity (VC)**: This is the maximum amount of air a person can exhale after a maximum inhalation. It is the sum of Tidal Volume (TV), Inspiratory Reserve Volume (IRV), and Expiratory Reserve Volume (ERV).

\[ VC = TV + IRV + ERV \]

### Step 2: Calculate Expiratory Reserve Volume (ERV)
Using the FRC and RV:

\[ ERV = FRC - RV \]

Substituting the given values:

\[ ERV = 2300 \, \text{ml} - 1200 \, \text{ml} = 1100 \, \text{ml} \]

### Step 3: Calculate Inspiratory Reserve Volume (IRV)
Using the IC and assuming a typical Tidal Volume (TV) of about 500 ml:

\[ IRV = IC - TV \]

Substituting the values:

\[ IRV = 3500 \, \text{ml} - 500 \, \text{ml} = 3000 \, \text{ml} \]

### Step 4: Calculate Vital Capacity (VC)
Now, we can calculate the VC using the formula:

\[ VC = TV + IRV + ERV \]

Substituting the known values:

\[ VC = 500 \, \text{ml} + 3000 \, \text{ml} + 1100 \, \text{ml} = 4600 \, \text{ml} \]

### Final Answer
The vital capacity (VC) is **4600 ml**.

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