2.2 Alveolar Ventilation

The exchange of oxygen and carbon dioxide between the lungs and the blood.

The equation used to calculate physiological dead space, taking into account both alveolar dead space and anatomical dead space.

Alveolar ventilation increases the partial pressure of oxygen (PO2) and decreases the partial pressure of carbon dioxide (PCO2) in the alveoli.

The total lung capacity (TLC) is determined by the strength of the inspiratory muscles because it represents the maximum volume of air the lungs can hold.

Decreasing functional residual capacity (FRC) will decrease expiratory reserve volume (ERV) because ERV is a component of FRC.

In obstructive lung disease, air gets trapped in the lungs, increasing residual volume (RV).

Spirometry cannot measure RV because it only measures lung volumes that can be exhaled.

A water-seal spirometer is a type of spirometer where the subject blows into a tube that ends in a water-filled container. It requires the subject to be awake and cooperative.

Closing volume is the lung volume at which the smallest airways start to close due to reduced tension from surrounding tissues.

During the second breath, oxygen initially enters the upper alveoli because they are the first to be ventilated after the dead space.

Tidal volume (TV) is the amount of air that moves into and out of the lungs with each normal breath.

Aging causes changes in lung elasticity and muscle strength, resulting in increased chest wall recoil and reduced lung volumes.

A significantly decreased functional residual capacity (FRC) can be caused by various conditions, including restrictive lung diseases, airway obstruction, and changes in posture.

Phase IV during expired gas measurement indicates the point at which dependent airways begin to close.

If a seated person inspires from residual volume, most of the inhaled gas will end up in the upper alveoli after the dead space is filled because gravity causes air to preferentially flow to the top of the lungs.

When transitioning from standing to supine position, residual volume (RV) and total lung capacity (TLC) may slightly decrease or remain unchanged due to redistribution of lung volume.

Restrictive lung diseases are characterized by reduced lung compliance (stiffness) and compressed lung volumes.

A spirometer is a device that measures lung volumes by recording the volume of air that the subject can breathe in and out.

In obstructive lung disease, functional residual capacity (FRC) is greatly increased because air gets trapped in the lungs.

In a healthy individual, an increase in physiological dead space usually occurs due to an increase in alveolar dead space, which happens when some alveoli are not properly perfused (blood flow) but are still ventilated (receiving air).

The main function of functional residual capacity (FRC) is to maintain a stable alveolar air composition by preventing excessive changes in oxygen and carbon dioxide levels.

Alveolar dead space refers to ventilation reaching alveoli that are not properly perfused (blood flow), while physiological dead space includes both alveolar dead space and anatomical dead space (airways that don't participate in gas exchange).

If dead space increases without compensation, the partial pressure of CO2 in blood will increase because less CO2 is being removed from the body.

The last 150 ml of air in the anatomical dead space remains not fresh during expiration because it's the last portion of air to move out of the respiratory tract.

True. Vital capacity (VC) decreases in obstructive lung disease because air gets trapped in the lungs, reducing the amount of air that can be exhaled.

True. Anatomical dead space is a part of physiological dead space. Physiological dead space is the sum of anatomical dead space and alveolar dead space.

False. The Bohr equation is used to measure physiological dead space, not alveolar ventilation.

True. Alveolar ventilation directly affects the partial pressure of gases in the alveoli, thus impacting alveolar gas tensions.

True. Functional residual capacity (FRC) tends to decrease when transitioning from standing to supine position due to changes in lung volume distribution.

True. Regional differences in alveolar ventilation occur at functional residual capacity (FRC) and residual volume (RV) due to the effects of gravity on lung volume distribution.

False. Closing volume is the volume of gas remaining in the lungs when small airways begin to close during expiration, not at the end of a normal tidal expiration.

False. Alveolar ventilation mainly impacts regional distribution of alveolar oxygen and carbon dioxide, not nitrogen.

True. Dalton's law explains the partial pressure of gases in a mixture, which applies to the composition of respiratory gases in the alveoli.

Standing position. Standing is the position where the functional residual capacity is normally highest.

Decreased alveolar ventilation. If most of the inspired air stays in the dead space, the alveoli will not be adequately ventilated.

An increase in residual volume. This is a paradoxical decrease because although the patient may have a large lung volume, the ability to exchange air quickly is reduced by the trapped air.