The largest volume of air which can be expelled from the lungs during expiration is called?

Appeared in: AIIMS Raipur NO - 2017 (Shift-1)

Explanation

Expiratory Reserve Volume (ERV) is defined as the maximum extra volume of air that can be expired by forceful expiration after the end of a normal tidal expiration.
While the question's phrasing 'largest volume...expelled' can be ambiguous, ERV is the specific term for the maximal reserve of air that can be voluntarily exhaled beyond a normal breath.
The average ERV in a healthy adult male is approximately 1100 mL, as shown in the provided spirometry diagram and standard physiological values.

Option A: Tidal volume is the amount of air moved during a normal, quiet breath (about 500 mL). It is not the maximal or 'largest' volume that can be forcibly expelled.
Option B: Residual volume is the air that remains in the lungs even after a maximal forced exhalation. By definition, it cannot be expelled.
Option C: Inspiratory Reserve Volume refers to the volume of air that can be inhaled (inspired), not exhaled (expelled). It is the opposite process.

Visual 1: Diagram - A labeled spirometry graph showing the different lung volumes (TV, IRV, ERV, RV) and capacities (VC, TLC). This helps visualize the definition of each term and the relationships between them.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Lung Volumes and Capacities as background academic context rather than a clinical decision trigger.
Measuring lung volumes via spirometry is a fundamental component of Pulmonary Function Tests (PFTs), which are crucial for diagnosing, monitoring, and managing respiratory diseases like asthma, COPD, and restrictive lung diseases.
A decreased ERV can be an indicator of conditions that restrict full lung deflation, such as obesity (due to abdominal mass), ascites, or certain neuromuscular diseases that weaken expiratory muscles.
What if? If a patient has advanced emphysema (a type of COPD), their Residual Volume (RV) would be significantly increased due to air trapping. This trapping of air reduces the space available for other volumes, leading to a decreased Expiratory Reserve Volume (ERV) and Vital Capacity (VC).

How to Approach the Question

This is a factual recall question that requires knowing the definitions of standard lung volumes.
First, carefully analyze the keywords in the question: 'largest volume,' 'expelled,' and 'expiration.'
Evaluate each option based on its physiological definition.
Eliminate 'Residual volume' because it cannot be expelled.
Eliminate 'Inspiratory reserve volume' because it relates to inhalation, not exhalation (expulsion).
Differentiate between 'Tidal volume' (normal breath) and 'Expiratory reserve volume' (maximal forced exhalation after a normal breath).

Concept Tested & Keywords

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Practise the full AIIMS Raipur NO - 2017 (Shift-1)

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