Question

Assertion: Functional residual capacity is equal to ERV+RV Reason: Expiratory capacity is equal to TV+IRV

Short answer

Both the assertions are correct and the reason is a valid explanation for the first assertion.

Step-by-step solution

Understanding Terminology

Begin by understanding the definitions of the terms mentioned in the exercise. FRC represents the amount of air left in the lungs after a normal exhalation, and is the sum of ERV and RV. ERV is the additional amount of air that can be expired from the lungs by determined effort after normal expiration. RV is the volume of air still remaining in the respiratory passages and lungs after the most forcible expiration possible. EC is the volume of air that can be forcibly exhaled after a normal exhalation, and is the sum of TV and IRV. TV is the amount of air inhaled or exhaled with each breath under resting conditions, while IRV is the maximum volume of air that can be inhaled over the normal tidal volume.

Validation the assertion and the reason

We can check if the assertions given in the exercise are correct or not. The First assertion is valid as expiration of FRC will indeed result in RV + ERV. The second statement is also correct, as EC does indeed equal TV + IRV.

Framing the conclusion

As both the assertions and reasons given in the exercise are true, and the reason is an appropriate explanation for the first assertion, the conclusion is that both assertions are correct and the reason is a valid one for the first assertion.

Key concepts

Functional Residual Capacity (FRC)

The Functional Residual Capacity (FRC) is essential to understanding lung capacity. It is the volume of air remaining in the lungs after a normal exhalation. This capacity serves as a buffer to keep the airways open and facilitate gas exchange during quiet breathing. Without FRC, our alveoli—the tiny sacs where gas exchange occurs—could collapse.
FRC can be calculated by adding Expiratory Reserve Volume (ERV) and Residual Volume (RV): \[ FRC = ERV + RV \] This equation helps healthcare professionals assess lung function and predict respiratory conditions.

• FRC aids in evaluating lung diseases like emphysema, where air trapping increases FRC.
• It is crucial for tests straddling the boundary of health and disease.

Keeping a healthy FRC is vital as it impacts general well-being and effective breathing.

Expiratory Reserve Volume (ERV)

Expiratory Reserve Volume (ERV) is the extra air that you can forcefully expel from your lungs after a normal breath out. Imagine blowing a balloon and squeezing out every last bit of air—even after you think you've blown out all you can. That's ERV!
ERV is part of the Functional Residual Capacity and is pivotal in maintaining healthy lung function. It accounts for how well you can clear out stale air and be ready for your next breath.

• High ERV usually indicates good lung elasticity and health.
• Low ERV could hint at restrictive airway conditions or decreased lung compliance.

Regular exercise can help maintain or improve ERV by keeping lungs and chest muscles strong.

Residual Volume (RV)

Residual Volume (RV) is the air left in your lungs after a full, forceful expiration. Even when you breathe out as much as possible, some air remains trapped. This is vital because:

• It prevents lung collapse by maintaining some volume.
• Ensures continuous exchange of gases, even between breaths.

RV is important for assessing how well lungs are functioning. In diseases like chronic obstructive pulmonary disease (COPD), RV might be increased, indicating air entrapment.
For a healthy respiratory system, RV should remain constant. This value helps doctors understand your lung function deeply and devise appropriate interventions if needed.

Tidal Volume (TV)

Tidal Volume (TV) is the amount of air that you typically inhale or exhale during a relaxed, normal breath. Think of it as your regular, everyday breath, the one you take without even thinking.
TV is crucial as it provides the baseline intake of oxygen and removal of carbon dioxide needed to sustain life. The volume changes dynamically with activity level and health conditions, showcasing the flexibility of the respiratory system.

• Normal TV varies based on age, gender, and physiological conditions.
• A decline in TV can suggest respiratory muscle weakness or lung disease.

Keeping a balanced TV is key to maintaining optimal respiratory function and overall health.

Inspiratory Reserve Volume (IRV)

Inspiratory Reserve Volume (IRV) represents the additional air that you can inhale after taking a normal breath in. Picture taking a deep breath to smell fresh flowers or inflate a balloon fully; that extra breath over the usual is IRV.
IRV is critical for activities that require more oxygen, like exercise, because it demonstrates the capacity of your lungs to take in more air as needed.

• High IRV can signal strong lung function and adaptability.
• Low IRV might suggest limited lung inflation ability, often seen in certain lung diseases.

Enhancing your IRV through respiratory exercises can be beneficial, particularly when improving your overall lung capacity and endurance.