Questions and Answers
How do intrapleural and intrapulmonary pressures change during breathing?
The intrapleural pressure is always less than the intrapulmonary pressure. The intrapulmonary pressure is subatmospheric during inspiration and greater during expiration.
How do lung compliance, elasticity, and surface tension affect breathing?
Lung compliance refers to the ease of expansion, elasticity is the tendency to recoil, and surface tension resists distension.
What is the significance of pulmonary surfactant?
Pulmonary surfactant lowers surface tension in alveoli to prevent collapse.
How are inspiration and expiration accomplished?
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How do pulmonary function tests relate to pulmonary disorders?
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How are partial gas pressures calculated?
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How is ventilation regulated by the CNS?
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How do blood gases and pH influence ventilation?
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Describe the changes in percent hemoglobin as a function of arterial PO2.
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What conditions influence the oxyhemoglobin dissociation curve?
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How is CO2 transported by the blood?
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What is the relationship between blood levels of CO2 and blood pH?
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Describe the acid-base balance of the blood and its respiratory system influence.
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What changes occur in the respiratory system in response to exercise training?
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What occurs in the respiratory system in response to high altitude?
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Study Notes
Breathing Mechanics
- Intrapleural pressure is consistently lower than intrapulmonary pressure, allowing lung inflation during inspiration.
- During inspiration, intrapulmonary pressure falls below atmospheric pressure, while it rises above atmospheric pressure during expiration.
- Boyle's law establishes the inverse relationship between gas volume and pressure, affecting lung dynamics.
Lung Properties
- Lung compliance refers to the volume change relative to transpulmonary pressure; higher compliance indicates easier lung expansion.
- Elasticity relates to the lungs' ability to recoil after distension, contributing to expiration.
- Alveolar surface tension acts inwardly, resisting lung expansion; pulmonary surfactant reduces this tension to prevent alveolar collapse.
Breathing Process
- Inspiration and expiration depend on striated muscle activity; diaphragm and external intercostals contract for inhalation.
- Quiet expiration results from muscle relaxation and elastic recoil of lungs, decreasing thoracic volume.
- Forced breathing involves accessory muscles augmenting ventilation efforts.
Ventilatory Assessment
- Spirometry is crucial for diagnosing pulmonary disorders, revealing decreased vital capacity in restrictive diseases.
- Obstructive diseases exhibit reduced forced expiratory volume due to increased airway resistance.
Gas Pressure Calculations
- Dalton's law states total gas pressure equals the sum of individual gas pressures.
- Partial pressure for each gas is calculated using its proportion in the mixture, with adjustments for altitude affecting total pressure.
Central Nervous System Regulation
- Medulla oblongata regulates respiratory muscles, while the pons provides modulation.
- Chemoreceptors monitor blood PCO2, pH, and PO2; PCO2 is more influential in respiratory regulation.
- Conscious control of breathing involves the cerebral cortex.
Blood Gas Influence on Ventilation
- Breathing is directly stimulated by blood PO2 levels when they fall below 50 mmHg.
- Stretch receptors in the lungs inhibit inspiration when tidal volumes exceed 1L, indicating lung fullness.
Oxygen Transport Mechanism
- Oxygen loading and unloading in hemoglobin depend on arterial PO2 and hemoglobin's affinity for oxygen.
- High PO2 in pulmonary capillaries promotes oxygen binding, while low PO2 in tissues facilitates oxygen release.
Oxyhemoglobin Dissociation Factors
- Blood pH and temperature alter hemoglobin's affinity for oxygen; lower pH or higher temperature decreases affinity (Bohr effect).
- Increased 2,3 DPG levels, found in anemia or low PO2 conditions, shift the oxyhemoglobin dissociation curve right, enhancing oxygen unloading.
CO2 Transport in Blood
- Carbonic anhydrase facilitates conversion of CO2 and H2O to carbonic acid, aiding CO2 transport via bicarbonate and hemoglobin.
- Chloride shift occurs in red blood cells during gas transport, balancing electrical charges resulting from bicarbonate diffusion.
Acid-Base Balance and Ventilation
- Ventilation influences blood CO2 levels, maintaining pH balance; normal arterial pH is approximately 7.4.
- Changes in ventilation lead to respiratory acidosis or alkalosis depending on levels of CO2 and bicarbonate.
Exercise-Induced Changes
- Increased ventilation (hyperpnea) occurs during exercise, matching metabolic demands to maintain normal arterial blood CO2 levels.
- Lactic acid production signals anaerobic metabolism at high exertion levels; endurance training improves oxygen utilization efficiency.
High Altitude Adaptations
- Acclimatization to altitude involves hyperventilation to compensate for reduced O2 availability.
- Increased production of 2,3 DPG allows for enhanced O2 unloading from hemoglobin; kidneys release erythropoietin to stimulate RBC production for better oxygen transport.
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Description
Test your understanding of intrapleural and intrapulmonary pressures with these flashcards from Chapter 16. This quiz explores how pressure changes during the breathing process, highlighting the mechanics of lung function. Perfect for students studying respiratory physiology.
