Lung Volumes and Capacities Practice Questions
60 free Lung Volumes and Capacities practice questions for the Physiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Tidal volume refers to the volume of air that is:
- A Expired forcibly after a maximal deep inspiration
- B Inspired or expired during normal quiet breathing
- C Remaining in the lungs after a maximal expiration
- D Exchanged only during forced rapid deep breathing
Correct answer: Inspired or expired during normal quiet breathing
Tidal volume is the amount of air inhaled or exhaled during normal, quiet breathing. In a healthy adult, it is approximately 500 mL.
Which lung volume cannot be measured directly by simple spirometry?
- A Tidal volume
- B Inspiratory reserve volume
- C Expiratory reserve volume
- D Residual volume
Correct answer: Residual volume
Residual volume is the air remaining in the lungs after maximal expiration. It cannot be measured directly using spirometry.
Inspiratory reserve volume represents the:
- A Maximum extra air inspired after normal inspiration
- B Air that is expired after a normal tidal expiration
- C Air remaining in lungs after forced full expiration
- D Volume of air inspired during normal quiet breathing
Correct answer: Maximum extra air inspired after normal inspiration
Inspiratory reserve volume is the additional air that can be inhaled after a normal tidal inspiration. It reflects inspiratory muscle strength.
Which combination constitutes vital capacity?
- A TV + IRV
- B IRV + ERV + RV
- C TV + IRV + ERV
- D TV + ERV + RV
Correct answer: TV + IRV + ERV
Vital capacity is the sum of tidal volume, inspiratory reserve volume, and expiratory reserve volume. It represents the maximum volume exhaled after full inspiration.
Functional residual capacity is the volume of air present in the lungs:
- A After maximal inspiration
- B After normal expiration
- C After forced expiration
- D During rapid breathing
Correct answer: After normal expiration
Functional residual capacity is the air remaining in the lungs after a normal expiration. It helps maintain alveolar gas exchange.
Which lung capacity includes residual volume?
- A Vital capacity
- B Inspiratory capacity
- C Functional residual capacity
- D Total inspiratory reserve capacity
Correct answer: Functional residual capacity
Functional residual capacity includes expiratory reserve volume and residual volume. It cannot be measured directly by spirometry.
Total lung capacity is defined as:
- A Air exhaled after forced inspiration
- B Air left after normal expiration
- C Sum of all the lung volumes
- D Air moved in tidal breaths
Correct answer: Sum of all the lung volumes
Total lung capacity is the sum of all lung volumes including residual volume. It represents the maximum amount of air the lungs can hold.
Which lung volume increases in obstructive lung disease?
- A Tidal volume
- B Residual volume
- C Vital capacity
- D Inspiratory reserve volume
Correct answer: Residual volume
Residual volume increases in obstructive lung diseases due to air trapping. Expiration becomes incomplete.
Expiratory reserve volume is the volume of air that:
- A Air inspired during a forced maximal inspiration
- B Air that remains after a forced full expiration
- C Air expired after a normal tidal expiration
- D Air moved in and out during quiet breathing
Correct answer: Air expired after a normal tidal expiration
Expiratory reserve volume is the extra air that can be expelled after a normal expiration. It reflects expiratory muscle strength.
Which capacity equals tidal volume plus inspiratory reserve volume?
- A Vital capacity
- B Inspiratory capacity
- C Functional residual capacity
- D Total lung capacity
Correct answer: Inspiratory capacity
Inspiratory capacity is the sum of tidal volume and inspiratory reserve volume. It represents the maximum air inspired after normal expiration.
Which lung volume is most affected in restrictive lung disease?
- A Residual volume
- B Tidal volume
- C Total lung capacity
- D Expiratory reserve volume
Correct answer: Total lung capacity
Restrictive lung disease reduces total lung capacity. Lung expansion is limited due to decreased compliance.
Which of the following volumes contributes to functional residual capacity?
- A Tidal volume
- B Inspiratory reserve volume
- C Expiratory reserve volume
- D Inspiratory capacity
Correct answer: Expiratory reserve volume
Functional residual capacity consists of expiratory reserve volume and residual volume. It maintains alveolar stability.
Closing volume refers to the lung volume at which:
- A Airway resistance is minimal
- B Small airways begin to close
- C Maximum expiration occurs
- D Alveoli are fully inflated
Correct answer: Small airways begin to close
Closing volume is the point during expiration when small airways start to close. It increases with age and lung disease.
Which lung volume remains relatively constant during exercise?
- A Tidal volume
- B Inspiratory reserve volume
- C Residual volume
- D Inspiratory capacity
Correct answer: Residual volume
Residual volume does not change significantly during exercise. It is determined mainly by lung structure.
Which parameter best reflects the elastic recoil of the lungs?
- A Tidal breathing volume
- B Residual air reserve volume
- C Functional residual capacity
- D Vital capacity measurement value
Correct answer: Functional residual capacity
Functional residual capacity reflects the balance between lung recoil and chest wall expansion. Changes indicate altered elasticity.
Which lung capacity decreases with aging?
- A Residual air
- B Functional reserve capacity
- C Vital capacity
- D Total lung capacity
Correct answer: Vital capacity
Vital capacity decreases with age due to reduced chest wall compliance. Residual volume tends to increase.
Which volume is used to calculate total lung capacity?
- A Vital capacity
- B Tidal volume
- C Functional reserve capacity
- D Residual air volume
Correct answer: Vital capacity
Total lung capacity equals vital capacity plus residual volume. Vital capacity is measurable by spirometry.
Which lung volume provides a reservoir for continuous gas exchange between breaths?
- A Tidal volume
- B Inspiratory reserve volume
- C Functional residual capacity
- D Vital capacity
Correct answer: Functional residual capacity
Functional residual capacity maintains a constant alveolar gas composition. It prevents large fluctuations in oxygen and carbon dioxide levels.
Which volume is reduced first in early restrictive lung disease?
- A Residual volume
- B Expiratory reserve volume
- C Tidal volume
- D Total lung capacity
Correct answer: Expiratory reserve volume
Expiratory reserve volume decreases early in restrictive lung disease. Lung expansion and contraction are both limited.
Which lung capacity is the maximum amount of air a person can inspire from the end of a normal expiration?
- A Inspiratory capacity
- B Vital capacity
- C Total lung capacity
- D Functional residual capacity
Correct answer: Inspiratory capacity
Inspiratory capacity equals tidal volume plus inspiratory reserve volume. It represents maximal inspiration after normal expiration.
A patient undergoes a pulmonary function test. Which of the following lung parameters can be measured using simple spirometry alone?
- A Functional Residual Capacity
- B Vital Capacity (VC)
- C Residual Volume
- D Total Lung Capacity (TLC)
Correct answer: Vital Capacity (VC)
Simple spirometry measures the volume of air moved into or out of the lungs. Since Residual Volume (RV) cannot be exhaled, any capacity containing RV—such as FRC, TLC, or RV itself—requires advanced techniques like helium dilution or body plethysmography.
Which of the following describes the state of the respiratory system when the lung volume is at Functional Residual Capacity (FRC)?
- A Alveolar pressure reaches its most negative possible value
- B Lung inward recoil balances outward chest wall recoil
- C The abdominal muscles actively contract to hold the volume
- D The lungs have reached their minimum possible volume
Correct answer: Lung inward recoil balances outward chest wall recoil
At FRC, which occurs at the end of a quiet expiration, the inward elastic recoil of the lungs and the outward elastic recoil of the chest wall are equal and opposite. This balance point establishes the resting equilibrium volume of the respiratory system.
During a transition from a standing to a supine (lying flat) position, which lung capacity is most significantly reduced?
- A Inspiratory Capacity of the lung (IC)
- B Total Lung Capacity value (TLC)
- C Functional Residual Capacity (FRC)
- D Vital Capacity of the lungs
Correct answer: Functional Residual Capacity (FRC)
When lying supine, the abdominal contents push upward against the diaphragm due to gravity, which reduces the resting volume of the lungs. This primarily results in a decrease in the Expiratory Reserve Volume (ERV) and thus the FRC.
In a healthy adult, if the Tidal Volume ($V_T$) is 500 mL, the Inspiratory Reserve Volume (IRV) is 3000 mL, and the Expiratory Reserve Volume (ERV) is 1100 mL, what is the Vital Capacity (VC)?
- A 3500 mL
- B 4100 mL
- C 4600 mL
- D 5800 mL
Correct answer: 4600 mL
Vital Capacity is the sum of the three volumes that can be voluntarily exchanged: $VC = IRV + V_T + ERV$. In this case, $3000 + 500 + 1100 = 4600$ mL.
In patients with emphysema, the destruction of alveolar walls leads to a loss of elastic recoil. How does this typically affect the Residual Volume (RV) and the RV/TLC ratio?
- A RV decreases; RV/TLC ratio remains constant
- B RV increases; RV/TLC ratio increases
- C RV increases; RV/TLC ratio decreases
- D Both RV and TLC decrease significantly
Correct answer: RV increases; RV/TLC ratio increases
Emphysema causes 'air trapping' because the airways collapse during expiration. This significantly increases the Residual Volume (RV), and because RV increases proportionally more than Total Lung Capacity (TLC), the RV/TLC ratio increases, indicating hyperinflation.
Which specific lung volume represents the volume of air that remains in the lungs after a maximal forceful expiration?
- A Tidal Volume
- B Expiratory Reserve Volume
- C Residual Volume
- D Minimal Volume
Correct answer: Residual Volume
The Residual Volume (RV) is the amount of air that cannot be expelled from the lungs regardless of effort. It prevents the alveoli from collapsing completely (atelectasis) and allows for continuous gas exchange between breaths.
A researcher uses the helium dilution method to determine a subject's lung volume. The formula used is $V_2 = V_1 \times \frac{C_1 - C_2}{C_2}$. If the initial volume of the spirometer ($V_1$) is 2 L, the initial helium concentration ($C_1$) is 10%, and the final concentration ($C_2$) is 5%, what is the subject's lung volume ($V_2$)?
- A 1 L
- B 2 L
- C 4 L
- D 5 L
Correct answer: 2 L
Using the law of conservation of mass: $V_2 = 2 \times \frac{10 - 5}{5} = 2 \times \frac{5}{5} = 2$ L. This method is commonly used to measure the Functional Residual Capacity (FRC).
Anatomical dead space refers to the volume of air in which of the following areas?
- A The alveoli that are ventilated but not perfused
- B The conducting airways where no gas exchange occurs
- C The total volume of the lungs at the end of a maximum inspiration
- D The volume of the pleural space
Correct answer: The conducting airways where no gas exchange occurs
Anatomical dead space includes the nose, pharynx, larynx, trachea, and bronchi down to the terminal bronchioles. This air does not reach the respiratory zone (alveoli) and therefore does not participate in gas exchange.
Which of the following changes is characteristic of a restrictive lung disease, such as pulmonary fibrosis?
- A Increased Total Lung Capacity value (TLC)
- B Decreased Functional Residual Capacity
- C Increased Residual Volume (RV)
- D Decreased RV/TLC ratio overall
Correct answer: Decreased Functional Residual Capacity
Restrictive diseases are characterized by stiff lungs that are difficult to expand. This results in a global reduction of all lung volumes and capacities, including TLC, VC, and FRC.
Closing Volume (CV) is the volume of air remaining in the lungs when:
- A Small airways in the lower dependent parts of the lungs begin to close
- B The glottis closes during a Valsalva maneuver
- C The volume reaches the Functional Residual Capacity
- D The surfactant stops working
Correct answer: Small airways in the lower dependent parts of the lungs begin to close
Closing volume occurs during expiration when the intrapleural pressure exceeds the airway pressure in the dependent (lower) regions of the lung, causing small airways to collapse. This volume typically increases with age and smoking.
During moderate exercise, which of the following adjustments in lung volumes typically occurs to increase minute ventilation?
- A Tidal Volume increases by encroaching on both IRV and ERV
- B Residual Volume decreases to allow for more Tidal Volume
- C Inspiratory Reserve Volume increases while Tidal Volume remains constant
- D Vital Capacity increases
Correct answer: Tidal Volume increases by encroaching on both IRV and ERV
To increase ventilation during exercise, the body primarily increases Tidal Volume. It does this by breathing 'deeper,' utilizing the reserve volumes available above and below a normal quiet breath.
What is the primary advantage of body plethysmography over helium dilution for measuring lung volumes?
- A It is far easier for the patient to actually perform
- B It measures all thoracic gas, including trapped air
- C It does not require the patient to breathe at all
- D It can measure Vital Capacity far more accurately
Correct answer: It measures all thoracic gas, including trapped air
Body plethysmography uses Boyle's Law ($P_1 V_1 = P_2 V_2$) to measure all gas within the chest. Unlike helium dilution, which only measures gas in communication with the airways, plethysmography accurately measures volumes even in patients with severe obstructive disease and trapped air.
In the third trimester of pregnancy, which of the following changes in lung volumes is most commonly observed?
- A Increase in Functional Residual Capacity (FRC)
- B Decrease in Vital Capacity (VC)
- C Decrease in Functional Residual Capacity (FRC)
- D Increase in Residual Volume (RV)
Correct answer: Decrease in Functional Residual Capacity (FRC)
The growing fetus elevates the diaphragm, which reduces the resting volume of the lungs. This leads to a decrease in the ERV and RV, resulting in a significantly lower FRC, though the Vital Capacity (VC) is usually preserved.
How is the Inspiratory Capacity (IC) calculated from standard lung volumes?
- A TLC - VC
- B TV + ERV
- C TV + IRV
- D FRC - RV
Correct answer: TV + IRV
Inspiratory Capacity (IC) is the maximum volume of air that can be inspired starting from the end of a normal expiration. It consists of the Tidal Volume ($V_T$) and the Inspiratory Reserve Volume (IRV).
Which of the following is true regarding the 'Minimal Volume' of the lungs?
- A It is exactly the same thing as the ordinary Residual Volume
- B It is the air remaining if the lungs collapse (pneumothorax)
- C It is the volume measured at the end of a normal breath
- D It is the value measured using a peak flow meter
Correct answer: It is the air remaining if the lungs collapse (pneumothorax)
Minimal volume is the small amount of air (approx. 30-120 mL) that remains trapped in the alveoli even if the lungs are removed from the chest or collapse. Residual Volume, by contrast, is the volume held in the lungs by the chest wall at the end of a maximal expiration.
If a patient has a Total Lung Capacity of 6.0 L and a Functional Residual Capacity of 2.5 L, what is their Inspiratory Capacity?
- A 8.5 L
- B 3.5 L
- C 2.5 L
- D 1.5 L
Correct answer: 3.5 L
The Total Lung Capacity is the sum of Inspiratory Capacity and Functional Residual Capacity ($TLC = IC + FRC$). Therefore, $IC = 6.0 - 2.5 = 3.5$ L.
What happens to the physiological dead space in a patient with a pulmonary embolism?
- A It decreases because less air is entering the lungs
- B It increases because some alveoli are ventilated but no longer perfused
- C It remains unchanged because it only depends on airway anatomy
- D It becomes equal to the Tidal Volume
Correct answer: It increases because some alveoli are ventilated but no longer perfused
Physiological dead space is the sum of anatomical dead space and alveolar dead space. In pulmonary embolism, blood flow to certain alveoli is blocked (perfusion failure), making them alveolar dead space and increasing the total physiological dead space.
Which lung capacity represents the maximum volume of air that can be exhaled after a maximum inspiration?
- A Total Lung Capacity
- B Tidal Volume
- C Vital Capacity
- D Inspiratory capacity
Correct answer: Vital Capacity
Vital Capacity (VC) is the total 'usable' volume of the lungs. It represents the maximum amount of air a person can move into or out of their respiratory system in a single breath.
In an elderly individual, which of the following lung volume changes is typically seen due to the normal aging process?
- A Increased Vital Capacity of the lung overall
- B Decreased Residual Volume overall
- C Increased Functional Residual Capacity
- D Decreased Total Lung Capacity (TLC)
Correct answer: Increased Functional Residual Capacity
With age, the lungs lose elastic recoil (becoming more 'compliant') and the chest wall becomes stiffer. This leads to an increase in FRC and Residual Volume (RV), while the Vital Capacity (VC) generally decreases.
Alveolar ventilation ($V_A$) is a better measure of gas exchange than minute ventilation because it accounts for:
- A The forced expiratory volume
- B Anatomical dead space
- C The oxygen carrying capacity of blood
- D The Residual Volume
Correct answer: Anatomical dead space
Minute ventilation is simply $V_T \times \text{frequency}$. Alveolar ventilation is calculated as $(V_T - V_D) \times \text{frequency}$, where $V_D$ is the dead space. This correctly identifies the volume of fresh air that actually reaches the gas-exchange surfaces.
Which of the following lung volumes or capacities CANNOT be measured by simple spirometry?
- A Vital Capacity (VC)
- B Inspiratory Capacity (IC)
- C Expiratory Reserve Volume (ERV)
- D Functional Residual Capacity (FRC)
Correct answer: Functional Residual Capacity (FRC)
Any capacity that includes the Residual Volume (RV) cannot be measured by simple spirometry. This includes FRC, RV, and Total Lung Capacity (TLC).
The sum of the Tidal Volume ($V_T$), Inspiratory Reserve Volume (IRV), and Expiratory Reserve Volume (ERV) is equal to the:
- A Total Lung Capacity (TLC)
- B Vital Capacity (VC)
- C Inspiratory Capacity (IC)
- D Residual Volume (RV)
Correct answer: Vital Capacity (VC)
Vital Capacity represents the maximum volume of air that can be exhaled after a maximum inhalation, encompassing IRV, $V_T$, and ERV.
At the end of a quiet, restful expiration, the volume of air remaining in the lungs is the:
- A Residual Volume (RV)
- B Expiratory Reserve Volume (ERV)
- C Functional Residual Capacity (FRC)
- D Minimal Volume
Correct answer: Functional Residual Capacity (FRC)
Functional Residual Capacity (FRC) is the volume remaining in the lungs at the end of a normal tidal expiration. It acts as a buffer for gas exchange.
A patient has a $V_T$ of 0.5 L, an IRV of 2.5 L, and an IC of 3.0 L. If their FRC is 2.4 L and their RV is 1.2 L, what is their TLC?
- A 4.2 L
- B 5.4 L
- C 3.6 L
- D 6.6 L
Correct answer: 5.4 L
Total Lung Capacity (TLC) can be calculated as IC + FRC. In this case, 3.0 L + 2.4 L = 5.4 L.
Which of the following changes in lung volumes is most characteristic of obstructive lung diseases like chronic bronchitis?
- A Increased Inspiratory Reserve Volume
- B Increased Functional Residual Capacity
- C Increased Vital Capacity
- D Decreased Total Lung Capacity
Correct answer: Increased Functional Residual Capacity
Obstructive diseases cause air trapping, which leads to increases in RV, FRC, and sometimes TLC due to hyperinflation.
In a healthy individual, which lung volume typically increases during exercise to accommodate larger tidal breaths?
- A Residual Volume
- B Expiratory Reserve Volume
- C Tidal Volume
- D Inspiratory Reserve Volume
Correct answer: Tidal Volume
During exercise, Tidal Volume increases by encroaching into both the Inspiratory and Expiratory Reserve Volumes.
If a subject's Vital Capacity is 4.8 L and their Inspiratory Capacity is 3.3 L, what is their Expiratory Reserve Volume (ERV)?
- A 1.5 L
- B 1.2 L
- C 2.1 L
- D 0.8 L
Correct answer: 1.5 L
Vital Capacity (VC) = Inspiratory Capacity (IC) + Expiratory Reserve Volume (ERV). Therefore, ERV = 4.8 - 3.3 = 1.5 L.
Which of the following describes the 'Minimal Volume' of the lung?
- A The volume of air remaining in the lungs after a normal, quiet expiration
- B The volume of air remaining in the lungs after the pleural cavity is opened
- C The extra amount of air that can be forcibly inhaled after a normal tidal breath
- D The fixed volume of air occupying the anatomical conducting dead space
Correct answer: The volume of air remaining in the lungs after the pleural cavity is opened
Minimal volume is the small amount of air trapped in the alveoli even if the lungs collapse (e.g., pneumothorax), which is slightly less than the Residual Volume.
What happens to the Functional Residual Capacity (FRC) when a person moves from a standing position to a supine position?
- A It increases because the diaphragm relaxes and moves downward slightly
- B It stays exactly the same regardless of body position or posture
- C It decreases because of the upward pressure of abdominal contents
- D It decreases solely because of an increase in overall lung compliance
Correct answer: It decreases because of the upward pressure of abdominal contents
In the supine position, gravity causes the abdominal viscera to push the diaphragm cephalad, reducing the resting volume of the lungs (FRC).
Restrictive lung diseases, such as sarcoidosis, are characterized by a decrease in:
- A All lung volumes and capacities
- B Only the residual volume itself
- C Just the FEV1 to FVC ratio
- D Only the tidal volume itself
Correct answer: All lung volumes and capacities
Restrictive diseases limit lung expansion, leading to a global reduction in volumes, including TLC, VC, and FRC.
Which technique for measuring FRC accounts for 'trapped' air that does not communicate with the main airways?
- A Closed-circuit helium dilution
- B Multiple-breath nitrogen washout
- C Simple spirometry
- D Body plethysmography
Correct answer: Body plethysmography
Body plethysmography uses Boyle's law to measure all gas in the thorax, including non-communicating or trapped air, unlike gas dilution methods.
Physiological dead space is the sum of anatomical dead space and:
- A Residual volume
- B Alveolar dead space
- C Tidal volume
- D Closing volume
Correct answer: Alveolar dead space
Physiological dead space includes all parts of the inspired air that do not participate in gas exchange: the conducting airways (anatomical) and non-perfused alveoli (alveolar).
If alveolar ventilation is 4.2 L/min, respiratory rate is 12 breaths/min, and tidal volume is 500 mL, what is the anatomical dead space?
- A 150 mL
- B 100 mL
- C 200 mL
- D 250 mL
Correct answer: 150 mL
Alveolar ventilation equals respiratory rate multiplied by (tidal volume minus dead space): 4200 = 12 x (500 - VD). Solving gives 350 = 500 - VD, so VD = 150 mL.
The volume of air that can be inspired over and above a normal tidal inspiration is the:
- A Inspiratory Capacity
- B Functional Residual Capacity
- C Inspiratory Reserve Volume
- D Total Lung Capacity
Correct answer: Inspiratory Reserve Volume
Inspiratory Reserve Volume (IRV) is specifically the extra volume inspired after a normal $V_T$ inhalation.
Which of the following is true regarding the Residual Volume (RV) in healthy aging?
- A It decreases due to increased muscle strength
- B It increases as a result of loss of lung elastic recoil
- C It remains constant throughout the lifespan
- D It only increases in the presence of smoking
Correct answer: It increases as a result of loss of lung elastic recoil
Aging involves a loss of elastic recoil (similar to mild emphysema) and weakening of respiratory muscles, both of which contribute to an increased RV.
A decrease in the Inspiratory Capacity (IC) while the Total Lung Capacity remains normal is often seen in:
- A Advanced interstitial pulmonary fibrosis
- B Strenuous high-intensity physical exercise
- C The third trimester of pregnancy
- D Obstructive disease with air trapping
Correct answer: Obstructive disease with air trapping
In obstructive disease, if FRC increases (due to air trapping) while TLC is constant, the IC (TLC - FRC) must decrease.
During the helium dilution test, if the final concentration of helium is higher than expected, it suggests the subject's lung volume is:
- A Larger than expected
- B Precisely equal to the spirometer volume
- C Unmeasurable
- D Smaller than expected
Correct answer: Smaller than expected
A higher final concentration means the helium was diluted into a smaller volume of air in the lungs.
Which of the following lung capacities is the best indicator of a patient's overall ventilatory reserve?
- A Tidal Volume
- B Functional Residual Capacity
- C Vital Capacity
- D Residual Volume
Correct answer: Vital Capacity
Vital Capacity measures the maximum amount of air available for gas exchange in a single breath, reflecting the functional reserve of the lungs.
In the 'Closing Volume' test, the sudden increase in nitrogen concentration (Phase IV) indicates:
- A Closure of airways in the base of the lung
- B Closure of airways in the apex of the lung
- C The start of tidal inspiration
- D The point of maximum inspiration
Correct answer: Closure of airways in the base of the lung
Airways at the base close first during expiration because they are less expanded. When they close, the remaining air comes from the apex, which has a higher nitrogen concentration.
If a patient has a Vital Capacity of 4.0 L and an Expiratory Reserve Volume of 1.0 L, what is their Inspiratory Capacity?
- A 5.0 L
- B 2.0 L
- C 3.0 L
- D 1.5 L
Correct answer: 3.0 L
Inspiratory Capacity (IC) = Vital Capacity (VC) - Expiratory Reserve Volume (ERV). 4.0 L - 1.0 L = 3.0 L.