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

Introduction to Lung Physiology

Anatomy & Physiology

22. The Respiratory System

Introduction to Lung Physiology

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Multiple Choice

Which of the following occurs during expiration?

The external intercostal muscles contract

The thoracic cavity volume increases

Air pressure in the lungs decreases below atmospheric pressure

The diaphragm relaxes and moves upward

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Verified step by step guidance

Understand the process of expiration: Expiration is the phase of breathing where air is expelled from the lungs. It is typically a passive process during normal breathing, relying on the relaxation of muscles and the elastic recoil of the lungs.

Identify the role of the diaphragm: During expiration, the diaphragm relaxes and moves upward into its dome-shaped position, reducing the volume of the thoracic cavity.

Examine the role of the external intercostal muscles: These muscles are primarily involved in inspiration, not expiration. During expiration, they relax, allowing the rib cage to return to its resting position.

Analyze the changes in thoracic cavity volume: As the diaphragm relaxes and moves upward, the thoracic cavity volume decreases, which increases the pressure inside the lungs.

Understand the pressure changes: During expiration, the air pressure in the lungs becomes greater than atmospheric pressure, forcing air out of the lungs. This is the opposite of the pressure changes during inspiration.