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Questions and Answers
What occurs during eupnea?
What is the primary effect of the diaphragm and external intercostals' recoil during expiration?
During more forceful expiration, which muscles are recruited in addition to the diaphragm and external intercostals?
What is the result of the diaphragm's contraction ending during forceful expiration?
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What triggers the airflow to exit the lungs during both eupnea and forceful expiration?
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What is the primary focus of the course in relation to the respiratory system?
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Which statement about Boyle’s Law is accurate?
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During inspiration, which pressure gradient occurs?
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What happens to pressures between breaths?
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How does pressure change when volume increases according to Boyle’s Law?
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In a hyperbaric environment, what occurs as a diver descends?
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What drives the process of ventilation?
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What is a role of gas transport in the respiratory system?
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What is the primary role of intrapleural pressure (Pip) during ventilation?
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Which muscle contributes 75% to the process of eupnea?
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What happens to alveolar pressure (Palv) during inspiration?
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Which accessory muscle is NOT involved in forceful inspiration?
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What pressure is always variable but remains subatmospheric during ventilation?
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In the context of ventilation and pressures, the inward pressure from the intrapleural space opposes which movement?
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What effect does the contraction of external intercostal muscles have on the thoracic cavity during quiet breathing?
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What change occurs in intrapleural pressure (Pip) when the diaphragm contracts during forced inspiration?
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Study Notes
Respiratory System Overview
- The respiratory system focuses on ventilation, gas exchange and gas transport.
- Ventilation is the process of air exchange between the atmosphere and alveoli.
- External respiration is gas exchange between alveoli and pulmonary capillaries.
- Internal respiration is gas exchange between tissue capillaries and interstitial fluid/tissue cells.
- Gas transport involves movement of gases by pulmonary and systemic circulations.
Ventilation: General Principles
- Atmospheric pressure at sea level is typically 760 mmHg.
- Pressure changes are often reported as relative to atmospheric pressure.
- Ventilation is driven by an air pressure gradient from high to low pressure.
- Inspiration (breathing in) occurs when atmospheric pressure (high) moves air to alveoli (low pressure).
- Expiration (breathing out) occurs when alveoli (high pressure) move air to the atmosphere (low pressure).
- Between breaths, pressures equalize, resulting in no air movement.
- To create a pressure gradient for ventilation, the pressure at the alveolar level must be manipulated.
Ventilation: Boyle's Law
- In a closed system at constant temperature, pressure (P) and volume (V) are inversely related.
- Increasing volume decreases pressure.
- Decreasing volume increases pressure.
- Changing volume alters the pressure gradient, driving ventilation.
- Boyle's Law applies to diving, where pressure changes influence volume.
Ventilation: Pressures
- Atmospheric pressure (Patm) is the environmental air pressure.
- Alveolar pressure (Palv) is the pressure within the alveoli.
- Intrapleural pressure (Pip) is the pressure within the intrapleural space between the visceral and parietal pleura.
- Intrapleural pressure is always subatmospheric, creating a pressure gradient that opposes lung elastic recoil and chest wall elastic recoil.
- This pressure gradient ensures that the lung and chest wall move as a unit.
Ventilation: Inspiration
- Diaphragm and external intercostals contract during inspiration.
- Eupnea, quiet breathing, involves 75% diaphragm and 25% external intercostal contraction.
- Diaphragm contraction flattens, increasing thoracic cavity volume.
- External intercostal contraction moves the chest wall outward and upward.
- Increased lung volume results in subatmospheric alveolar pressure, drawing air into the lungs.
Ventilation: Expiration
- Diaphragm and external intercostals stop contracting during expiration.
- Eupnea involves recoil back to pre-inspiration positions.
- Diaphragm relaxes, returning to its dome shape, decreasing lung volume.
- External intercostals relax, moving the chest wall inward and downward.
- Decreased lung volume compresses alveoli, increasing alveolar pressure above atmospheric pressure, forcing air out of the lungs.
Ventilation: Forceful Breathing
- Stronger diaphragm and external intercostal contractions during inspiration result in greater lung volume expansion and a larger pressure gradient.
- Accessory muscles of inspiration (scalenes, sternocleidomastoid, pectoralis minor) contribute to further chest wall movement and air flow.
- Stronger diaphragm and external intercostal contractions during expiration result in greater lung volume compression and a larger pressure gradient.
- Accessory muscles of expiration (internal intercostals, abdominals) contribute to further chest wall movement and air flow.
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Description
This quiz covers the fundamentals of the respiratory system, including ventilation, gas exchange, and gas transport. Understand the processes of external and internal respiration, and how atmospheric pressure affects breathing. Test your knowledge on the mechanisms that drive the respiratory functions.
