Lung Volumes and Capacities

The respiratory system's efficiency in delivering oxygen and carbon dioxide depends solely on the volume of the lungs.

The rate of respiration remains constant at 12-16 breaths per minute, regardless of conscious effort.

The respiratory cycle consists of inspiration, expiration, and a consistent pause.

Lung volumes refer to the combination of two or more lung capacities making up the total lung volume.

Tidal Volume (TV) represents the amount of air inspired or expired during a forced, deep breath.

The average Tidal Volume is approximately 750 ml in both males and females.

Inspiratory Reserve Volume (IRV) is the amount of air that can be forcibly inspired in addition to a normal inspiration.

Expiratory Reserve Volume (ERV) is the maximum amount of air remaining in the lungs after a maximal exhalation.

Residual Volume (RV) is the amount of air that remains trapped in the lungs even after maximal exhalation.

Lacking surfactant, alveoli tend to fully empty during exhalation, decreasing the lungs residual volume.

Vital Capacity (VC) describes the minimal volume of air a person can expel from the lungs, reached after a quiet expiration.

Inspiratory Capacity (IC) is the amount of air a person can breathe in with maximum effort, starting from the end of a normal inhalation.

Total Lung Capacity (TLC) represents the volume of air present in the lungs after maximal exhalation.

The values for respiratory volumes and capacities are consistent across all individuals, regardless of sex, size, or age.

Minute Ventilation is calculated by multiplying the tidal volume by the rate of respiration.

Alveolar ventilation accounts for the air remaining in the upper respiratory passages, which exchanges gases.

Maximum Voluntary Ventilation (MVV) measures the amount of air that can be moved into or out of the lungs with minimal effort over a prolonged period.

Measurements of respiratory volumes and capacities can completely determine the ability to move air in and out of the lungs.

In restrictive pulmonary diseases, lung volumes and capacities are generally normal.

Silicosis results in increased dispensability and decreased stiffness of the lungs.

In obstructive pulmonary diseases, excess mucous secretion generally widens airways, facilitating easier breathing.

In asthma, respiratory volumes are always significantly reduced.

The subject should avoid practicing breathing through the spirometer mouthpiece before measurement.

When measuring expiratory reserve volume the subject should inhale then exhale maximally into the device three times, recording the smallest volume in the table.

When utilizing a handheld spirometer the device can be used for both inhalation and exhalation.

The normal value for Tidal Volume is approximately 500 mL.

A person can typically inhale more air than they can exhale.

The normal value for Expiratory Reserve Volume (ERV) is approximately 1200 mL.

The normal value for Vital Capacity is approximately 4700 mL.

The Inspiratory Reserve Volume (IRV) can be calculated using the formula: VC + ERV - TV.

An increased rate of alveolar ventilation results in a lower concentration of carbon dioxide in the body.

The formula to determine the Functional Residual Capacity (FRC) is: ERV + RV. This result when calculated should be around 2500 ml.

If a patient has an obstructive pulmonary disease, their vital capacity is always higher than healthy individuals, due to them taking larger breaths.

The primary goal of measuring respiratory function is to quantify lung diseases and is of no help when determining drug dosage.

The volume of anatomical dead space remains fixed relative to the respiratory rate during activities like exercise or singing.

Airway secretions have no impact on lung volumetric measures.

An increase in Tidal Volume will always be matched by a corresponding reduction in respiratory rate to maintain stable blood pH.

Variations in the respiratory rate, depth, and rhythm are solely attributed to conscious breathing efforts.

Increasing lung capillary perfusion decreases alveolar ventilation, since less time is available for carbon dioxide and oxygen transfer.

Respiratory rate is inversely related to the duration of the pause between breaths.

Individuals with reduced lung size typically have Inspiratory Reserve Volumes closest to 3000 ml.