Respiratory Anatomy and Mechanics

Questions and Answers

What happens to alveolar pressure when the volume of air in the lungs increases?

It remains constant regardless of volume changes.

It decreases significantly below zero.

It rises to equal atmospheric pressure. (correct)

It becomes more negative than atmospheric pressure.

Which muscles are primarily involved in lifting the first two ribs during inhalation?

Internal intercostals

Diaphragm

Scaleni (correct)

Abdominal recti

What effect does the pleural fluid have on the lungs within the thoracic cavity?

It creates a suction effect between lung pleura. (correct)

It isolates the lungs from reaching the diaphragm.

It decreases the volume of the lungs.

It increases pleural pressure significantly.

During expiration, which muscle is NOT typically engaged?

Scaleni Signup and view all the answers

What is the state of pleural pressure at rest when no air is flowing into the lungs?

It is more negative than atmospheric pressure. Signup and view all the answers

What is the primary factor affecting transmural pressure across the chest wall?

Difference between pleural pressure and atmospheric pressure Signup and view all the answers

What does lung compliance measure?

Extent to which the lungs expand for each unit increase in transpulmonary pressure Signup and view all the answers

What is the average total compliance of both lungs together based on transpulmonary pressure?

200 mL of air per 1 cm of water Signup and view all the answers

What would be the effect of saline fluid in the alveoli on lung function?

Eliminates the elastic forces of pulmonary surfactant Signup and view all the answers

How is transpulmonary pressure adjusted during ventilation?

By adjusting pleural pressure while maintaining atmospheric pressure Signup and view all the answers

What is the compliance value of the combined lung-thorax system?

110 mL/cm Signup and view all the answers

During quiet breathing, what happens to the muscles of respiration during expiration?

They undergo passive relaxation. Signup and view all the answers

What does the work of breathing primarily define?

The energy expended against certain resistance. Signup and view all the answers

What is nearly half the compliance of the lungs when considered alone?

Compliance of the thoracic cage only. Signup and view all the answers

What type of system does spirometry evaluate?

The changes in lung volume during breathing. Signup and view all the answers

How is the compliance of the entire pulmonary system measured?

During total relaxation or paralysis of the subject. Signup and view all the answers

Which of the following best describes the role of O2 and CO2 electrodes in spirometry?

They continuously monitor partial pressures of O2 and CO2. Signup and view all the answers

What primarily causes the elastic recoil during expiration?

The inherent elasticity of lung tissues. Signup and view all the answers

What primarily keeps the airways open in the larger bronchi and bronchioles?

Transpulmonary pressure Signup and view all the answers

What role does the mucus layer play in the respiratory passages?

Traps microparticles and keeps the epithelium moist Signup and view all the answers

Which structural components are primarily responsible for keeping the trachea open?

Cartilage rings and plates Signup and view all the answers

What is the maximum size of microparticles that can be effectively trapped by the mucus layer in the respiratory tree?

10 µm Signup and view all the answers

What type of bronchoconstriction is associated with the parasympathetic nervous system?

Bronchoconstriction via lung tissue interaction Signup and view all the answers

What is the volume of air that can be forcefully expelled from the lungs after maximum inhalation?

Expiratory Reserve Volume Signup and view all the answers

Which pulmonary capacity is equivalent to the sum of the tidal volume and inspiratory reserve volume?

Inspiratory Capacity Signup and view all the answers

Which of the following statements about pulmonary volumes is incorrect?

All pulmonary volumes are about 20-25% greater in women than in men. Signup and view all the answers

What is the typical value of the Inspiratory Reserve Volume in an adult male?

3000 mL Signup and view all the answers

What is the definition of Total Lung Capacity?

The sum of the vital capacity and the residual volume. Signup and view all the answers

Which pulmonary volume represents the air that cannot be forcibly expired from the lungs?

Residual Volume Signup and view all the answers

Which of the following volumes is typically less in women compared to men?

These all have a lower value in women. Signup and view all the answers

What is the approximate volume of the Expiratory Reserve Volume in an adult male?

1100 mL Signup and view all the answers

Study Notes

Mechanics of Respiration

Changes in pleural pressure coincide with increased lung air volume, from 0 to approximately 0.5 liters.
Scaleni muscles assist in lifting the first two ribs during breathing.
Alveolar pressure at rest has a slight negative pressure aiding lung inflation, which rises to 0 cm of water with increased air volume, equalizing with atmospheric pressure.

Transmural Pressure

Transmural pressure (Pw) is generated by the difference between pleural pressure (Ppl) and surrounding atmospheric pressure (Pb).
Lung compliance refers to how much the lungs expand with each unit of transpulmonary pressure, averaging 200 mL of air per 1 cm of water.

Lung Compliance and Thoracic Cage

Lung-thorax system compliance is approximately half of lung-only compliance.
Combined system compliance is 110 mL/cm, while lungs alone are 220 mL/cm.
Measurement occurs with relaxed or paralyzed subjects to assess the pulmonary system’s compliance.

Spirometry and Work of Breathing

Spirometry evaluates lung volume changes—essential for understanding pulmonary ventilation.
During quiet breathing, respiratory muscles contract for inspiration, with passive relaxation for expiration due to elastic recoil.
Work against resistance is central to breathing effort; assessed through oxygen and carbon dioxide electrodes.

Pulmonary Volumes

Tidal Volume (TV) is the volume of air with each normal breath, averaging 500 mL in adult males.
Inspiratory Reserve Volume (IRV): 3000 mL, inspired above normal tidal volume.
Expiratory Reserve Volume (ERV): 1100 mL, maximum extra air expired after normal tidal expiration.
Residual Volume (RV): 1200 mL of air remains post-forceful expiration, not removable via regular breathing.
Total Lung Capacity (TLC) is about 5800 mL, combining vital capacity and residual volume.
Pulmonary volumes vary, being 20-25% less in women and higher in athletic individuals.

Respiratory Passage Function

Airways, including trachea and bronchi, are supported by cartilage rings, maintaining openness.
Smaller bronchioles mainly rely on transpulmonary pressure for patency as they contain smooth muscle only.
Mucus lining throughout respiratory pathways traps microparticles and keeps epithelium moist.
Ciliary action clears passageways, ensuring efficient respiratory function despite potential bronchoconstriction.

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Description

This quiz delves into the anatomy and mechanics of respiration, focusing on the role of muscles during inhalation and exhalation. It highlights the intricate relationship between pleural pressure changes and lung volume. Perfect for students studying respiratory physiology.