Lung Volumes Flashcards

Questions and Answers

What is tidal volume and inspiratory reserve volume?

Tidal volume is the volume of air that moves in and out of the lungs during inspiration and expiration. Inspiratory reserve volume is the maximum volume of air that can be inspired on the deepest inspiration, above the tidal volume.

Define functional residual capacity and expiratory reserve volume.

Functional residual capacity is the volume of air left in the lungs after expiration at rest. Expiratory reserve volume is the volume of air that can be expired on forced expiration.

Define residual volume. What physiologic or anatomic factors affect it?

Residual volume is the fixed volume of air that cannot be removed even with forced expiration. It is affected by the strength of respiratory muscles, stiffness of the chest wall, lung compliance, and airway patency.

Define vital capacity and total lung capacity.

Vital capacity is the maximal volume that can be exhaled after maximal inhalation, which is the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume. Total lung capacity is the total air volume of both lungs at the end of maximal inspiration. Signup and view all the answers

Differentiate between anatomic dead space, alveolar dead space, and physiologic dead space.

Anatomic dead space is the volume of air in the conducting airways that does not participate in gas exchange. Alveolar dead space is an abnormal finding in mammals and consists of alveoli that are not exchanging gas. Physiologic dead space is the combined volume of anatomic and alveolar dead spaces. Signup and view all the answers

What factor is more important in increasing the alveolar ventilation rate - increased depth or increased rate of breathing? Why?

Increased depth of breathing is more important in increasing the alveolar ventilation rate than the respiratory rate. Signup and view all the answers

Define hypo- and hyperventilation.

Hypoventilation is an increase in CO2 production compared to the alveolar ventilation rate, while hyperventilation occurs when too much CO2 is being eliminated compared to the alveolar ventilation rate. Signup and view all the answers

Where in the CNS is the cyclic activity of inspiration controlled? What muscles does it affect? Which drugs cause respiratory depression and death? Which drugs affect the respiratory skeletal muscles?

The cyclic activity of inspiration is controlled by the medulla oblongata, affecting the diaphragm and inspiratory intercostal muscles. Drugs like barbiturates and opiates cause respiratory depression, while succinylcholine and other nicotinic antagonists affect respiratory skeletal muscles. Signup and view all the answers

Where are the central chemoreceptors located that control ventilation rate? What stimulus results in an increase in tidal volume, and therefore alveolar ventilation rate?

Central chemoreceptors are located on the ventral surface of the 4th cerebral ventricle. They are stimulated by an increase in brain ECF hydrogen ions, which occurs due to an increase in CO2 in the blood. Signup and view all the answers

What are the locations of the two peripheral chemoreceptor groups, and what do they signal?

The two peripheral chemoreceptor groups are the carotid bodies located in the bifurcation of the common carotid arteries, signaling via the glossopharyngeal nerve, and the aortic bodies located at the aortic arch, signaling through the vagus nerve. Signup and view all the answers

Study Notes

Lung Volumes and Definitions

Tidal Volume (V(T)): Volume of air exchanged during normal breathing.
Inspiratory Reserve Volume: Maximal additional air that can be inhaled beyond tidal volume.

Functional Capacities

Functional Residual Capacity (FRC): Volume of air remaining in the lungs post-expiration at rest.
Expiratory Reserve Volume (ERV): Additional air that can be forcibly exhaled after normal expiration.

Residual Volume

Residual Volume (RV): Air remaining in lungs post-forced expiration; prevents airway collapse.
Influenced by respiratory muscle strength, chest wall stiffness, lung compliance, and airway openness.

Vital and Total Lung Capacity

Vital Capacity (VC): Maximum air exhaled after full inhalation (VC = IRV + V(T) + ERV).
Total Lung Capacity (TLC): Overall lung volume at maximum inhalation.

Dead Space Types

Anatomic Dead Space: Air in conducting airways (trachea to bronchioles) not involved in gas exchange.
Alveolar Dead Space: Non-functioning alveoli that do not participate in gas exchanges.
Physiologic Dead Space: Combined volume of anatomic and alveolar dead spaces.

Alveolar Ventilation

Increased Depth of Breathing: More impactful than increased respiratory rate in enhancing alveolar ventilation, as it minimizes dead space air exchange.

Ventilation Definitions

Hypoventilation: Increased CO2 production exceeding alveolar ventilation, leading to elevated CO2 levels (PCO2 > 40 mmHg).
Hyperventilation: Excess CO2 elimination compared to production, resulting in low CO2 levels (PCO2 < 40 mmHg).

Control of Inspiration

Medulla Oblongata: Central control center for inspiration; activates diaphragm and intercostal muscles.
Respiratory Depressant Drugs: Barbiturates and opiates can cause respiratory failure.
Skeletal Muscle Effects: Nicotinic antagonists like succinylcholine affect respiratory muscle function.

Chemoreceptor Functions

Central Chemoreceptors: Located on the ventral surface of the 4th cerebral ventricle; responsive to increases in CO2 and resultant H+ ions, enhancing tidal volume and ventilation.
Inert to O2 Levels: Central chemoreceptors do not respond to oxygen pressure changes.

Peripheral Chemoreceptors

Carotid Bodies: Located at the carotid artery bifurcation, signaling through the glossopharyngeal nerve; stimulated by low arterial O2.
Aortic Bodies: Found at the aortic arch, signaling through the vagus nerve; similar stimulation by decreased oxygen levels.

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Description

Test your knowledge on lung volumes with these flashcards. Learn about tidal volume, inspiratory reserve volume, and functional residual capacity. Perfect for students studying respiratory physiology.