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

Why is the actual flow of air into the alveoli during inspiration considered passive?

Because the diaphragm pushes air into the lungs by direct force.

Because air moves into the alveoli due to a pressure gradient created by the expansion of the thoracic cavity.

Because the alveolar walls actively contract to draw air in.

Because oxygen is actively transported across the respiratory membrane.

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Verified step by step guidance

Understand the concept of passive air flow: Passive processes in physiology occur without direct energy expenditure or active force. In the case of air flow into the alveoli, it is driven by pressure gradients rather than active muscular contraction or energy-dependent transport.

Review the mechanics of inspiration: During inspiration, the diaphragm and external intercostal muscles contract, increasing the volume of the thoracic cavity. This expansion reduces the pressure inside the lungs relative to atmospheric pressure.

Apply Boyle's Law: Boyle's Law states that pressure and volume are inversely related in a closed system. As the thoracic cavity expands, the pressure inside the lungs decreases, creating a pressure gradient where air moves from the higher atmospheric pressure to the lower pressure inside the alveoli.

Clarify why this process is passive: The movement of air into the alveoli occurs due to the pressure gradient created by the expansion of the thoracic cavity. No active force is exerted by the alveoli themselves, and the process does not require direct energy expenditure for air movement.

Eliminate incorrect options: The diaphragm does not push air into the lungs by direct force, alveolar walls do not actively contract to draw air in, and oxygen is not actively transported across the respiratory membrane during inspiration. The correct explanation is the pressure gradient created by thoracic cavity expansion.