Questions and Answers
How does anatomical dead space differ from physiological dead space?
What can the Bohr equation be used to calculate?
Physiological dead space.
What three assumptions are made when using the Bohr equation to calculate physiological dead space?
All CO2 comes from alveolar gas (not dead space), arterial CO2 equals alveolar CO2, and conservation of mass.
What is minute ventilation a measure of?
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What are the two components of minute ventilation?
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If tidal volume increases, how will alveolar ventilation and dead space ventilation change?
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If respiratory frequency increases, how will alveolar ventilation and dead space ventilation change?
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Is increasing tidal volume or respiratory frequency more efficient in increasing alveolar ventilation? Why?
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What does the respiratory exchange ratio refer to?
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How does respiratory exchange rate differ from respiratory quotient?
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When does the respiratory exchange ratio equal the respiratory quotient?
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What effect does increasing alveolar ventilation have on alveolar CO2 pressure and O2 pressure?
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What effect does an increase in metabolic activity have on the alveolar pressure of oxygen?
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What value is used to define hyper and hypoventilation? What does this value assess?
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What effect does hypothyroidism have on ventilation? What will this do to alveolar pressure of CO2?
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What is the ideal alveolar gas equation used to measure?
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What is the alveolar ventilation equation used to measure?
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What is the normal A-a difference range (mmHg) for pressure of oxygen? What is the normal a/A pressure ratio of oxygen?
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What is the clinical term for normal spontaneous breathing?
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How does hyperpnea differ from hyperventilation?
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What is the clinical term for increased frequency of breathing? If tidal volume is also increased, what happens to alveolar ventilation?
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A temporary absence of breathing which resumes spontaneously is referred to as what clinically?
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Study Notes
Anatomical vs. Physiological Dead Space
- Anatomical dead space is the lung volume not involved in gas exchange.
- Physiological dead space includes anatomical dead space plus any non-functioning alveoli (alveolar dead space).
Bohr Equation
- Used to calculate physiological dead space.
- Assumes all CO2 originates from alveolar gas, arterial CO2 equals alveolar CO2, and conservation of mass holds true.
Minute Ventilation
- Represents the volume of air inhaled per minute.
- Calculated as the product of tidal volume (TV) and respiratory frequency (f).
Components of Minute Ventilation
- Consists of alveolar ventilation and dead space ventilation.
Effects of Tidal Volume and Respiratory Frequency
- Increasing tidal volume boosts alveolar ventilation; dead space ventilation remains unchanged.
- Increasing respiratory frequency elevates both alveolar ventilation and dead space ventilation.
Efficiency of Increasing Alveolar Ventilation
- Increasing tidal volume is more efficient for enhancing alveolar ventilation than increasing respiratory frequency since the latter also increases dead space ventilation.
Respiratory Exchange Ratio (RER)
- Defined as the rate of CO2 expiration to the rate of O2 reaching the alveoli, typically less than one.
Respiratory Exchange Ratio vs. Respiratory Quotient
- RER indicates the CO2 to O2 ratio at the respiratory level (expired vs. inhaled).
- Respiratory quotient refers to the CO2 to O2 ratio at the metabolic level (produced vs. used).
Steady State Relationship
- RER equals respiratory quotient when in steady state.
Effects of Increased Alveolar Ventilation
- Raises alveolar O2 pressure while reducing alveolar CO2 pressure.
Impact of Metabolic Activity on Alveolar Pressure
- An increase in metabolic activity results in a decline of alveolar O2 pressure.
Hyperventilation and Hypoventilation Definition
- Defined by alveolar CO2 pressure; assesses adequacy of ventilation relative to metabolic activity.
Impact of Thyroid Function on Ventilation
- Hyperthyroidism escalates ventilation rates, decreasing alveolar CO2 pressure.
Alveolar Gas Equations
- Ideal alveolar gas equation determines alveolar pressure of oxygen.
- Alveolar ventilation equation assesses alveolar pressure of carbon dioxide.
Normal Ranges for A-a Difference
- The normal A-a difference for oxygen pressure is 5-20 mmHg.
- Normal a/A pressure ratio for oxygen is approximately 0.8.
Clinical Terms
- Eupnea refers to normal spontaneous breathing.
- Tachypnea denotes an increased breathing rate; if tidal volume rises, alveolar ventilation also increases.
- Apnea describes a temporary absence of breathing that resumes spontaneously.
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Description
Test your knowledge on key concepts related to ventilation in physiology with these flashcards. Cover topics such as anatomical and physiological dead space, including the Bohr equation and its calculations. Perfect for students looking to reinforce their understanding of respiratory function.