Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

22. The Respiratory System

Pressure in the Lungs and Pleural Cavity

Anatomy & Physiology

22. The Respiratory System

Pressure in the Lungs and Pleural Cavity

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Problem 8

Textbook Question

Which of the following statements about pulmonary ventilation is false?
a. Normal expiration requires the use of the expiratory muscles to decrease lung volume.
b. The inspiratory muscles increase lung volume, which decreases intrapulmonary pressure.
c. For inspiration to occur, intrapulmonary pressure must decrease below atmospheric pressure.
d. The intrapleural pressure is less than the intrapulmonary pressure; this prevents the lungs from collapsing during expiration.

Verified step by step guidance

Step 1: Understand the concept of pulmonary ventilation, which involves the movement of air into and out of the lungs. It is driven by pressure differences between the atmosphere and the lungs.

Step 2: Review the mechanics of inspiration. During inspiration, the inspiratory muscles (diaphragm and external intercostals) contract, increasing lung volume and decreasing intrapulmonary pressure below atmospheric pressure, allowing air to flow into the lungs.

Step 3: Examine the mechanics of expiration. Normal expiration is typically a passive process that relies on the elastic recoil of the lungs and thoracic cavity. Expiratory muscles (e.g., internal intercostals and abdominal muscles) are only actively used during forced expiration.

Step 4: Analyze the role of intrapleural pressure. Intrapleural pressure is always less than intrapulmonary pressure, creating a negative pressure that prevents lung collapse by keeping the lungs adhered to the thoracic wall.

Step 5: Evaluate each statement in the problem. Compare the mechanics of pulmonary ventilation to the statements provided. Identify the false statement by determining which one contradicts the physiological processes described above.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Pulmonary Ventilation

Pulmonary ventilation refers to the process of moving air in and out of the lungs, which is essential for gas exchange. It involves two main phases: inspiration, where air is drawn into the lungs, and expiration, where air is expelled. Understanding the mechanics of these phases, including the roles of various muscles and pressures, is crucial for analyzing statements about ventilation.

Intrapulmonary and Intrapleural Pressure

Intrapulmonary pressure is the pressure within the lung alveoli, while intrapleural pressure is the pressure within the pleural cavity surrounding the lungs. During normal breathing, intrapulmonary pressure fluctuates with the phases of ventilation, whereas intrapleural pressure remains consistently lower than intrapulmonary pressure, which helps keep the lungs inflated and prevents collapse.

Role of Respiratory Muscles

The respiratory muscles, including the diaphragm and intercostal muscles, play a vital role in altering lung volume and pressure during breathing. During inspiration, these muscles contract to increase lung volume, leading to a decrease in intrapulmonary pressure. Conversely, during expiration, the muscles relax, allowing lung volume to decrease, which increases intrapulmonary pressure and facilitates air expulsion.

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Related Practice

Textbook Question

When the diaphragm and external intercostal muscles contract,

(a) Exhalation occurs.

(b) Intrapulmonary pressure increases.

(d) The volume of the lungs decreases.

(e) The size of the thoracic cavity increases.

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Multiple Choice

During inspiration, air moves into the lungs because __________.

Which of the following does not affect the efficiency of pulmonary gas exchange?

a. The surface area of the respiratory membrane

b. The degree of match of ventilation to perfusion

c. The percent saturation of hemoglobin

d. The thickness of the respiratory membrane

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Multiple Choice

The transpulmonary pressure is the difference between the __________ and the __________ pressure.

Match each term with the correct definition.

Airway resistance

Surface tension

Surfactant

Pulmonary compliance

V/Q ratio

a. A detergent-like chemical secreted by bronchial smooth muscle that reduces surface tension

b. The matching of ventilation to perfusion

c. Largely determined by the diameter of the airways

d. Caused by the formation of hydrogen bonds between water molecules

e. Determined by the surface tension of the alveoli, the elastic tissue of the lungs, and the condition of the chest wall

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Textbook Question

If you swallow a large bite of food without properly chewing it first, you will feel discomfort during ventilation. Explain this, considering the arrangement of the trachea and the esophagus.

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Textbook Question

As a result of a stroke, Mrs. Minnick's swallowing is uncoordinated. What detrimental effect might this have on her ability to breathe?

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Multiple Choice

What type of pressure keeps the air spaces in the lungs open?