Questions and Answers
Anatomical dead space is composed of the alveoli that have no capillary blood supply.
True
Air flows when the pressure gradient is greater than the resistance opposing the flow.
True
Dry, unpolluted atmospheric air is composed of 79.04% oxygen, 20.93% carbon dioxide, and 0.03% nitrogen.
False
As altitude increases, the percentage of oxygen in the air decreases, while the barometric pressure remains the same.
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Hyperventilation lengthens breath-holding time by increasing the PAO2 mmHg.
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Only about 1.5-3% of oxygen is transported dissolved in the liquid portion of the blood, but it is this oxygen that is responsible for the PO2 mmHg.
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In arterial blood at a PO2 of 95 mmHg, the saturation of hemoglobin with oxygen is 97%.
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All pulmonary venous blood is fully oxygenated.
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In normal, healthy, sedentary, or moderately fit individuals, respiration is a major limiting factor in performing exercise.
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Minute ventilation responds immediately to exercise with an abrupt increase that is maintained for about 20-30 seconds.
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The best overall indicator of internal respiration is the arterio-venous oxygen difference (a-vO2diff).
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The higher the workload/work rate at which the ventilatory thresholds occur, the greater the intensity of endurance activity that can be sustained.
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Maintaining PaO2 during exercise is important because it represents the driving force for oxygen and carbon dioxide transfer across the alveolar-capillary interface.
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Athletes who train at altitude usually see improved performance if the competition is at the same altitude as the training.
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What is the origin of cyclic neural impulses that stimulate inspiratory muscles to contract?
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What is the origin of maintenance of inspiratory tone and stimulation of expiratory muscles?
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Which center constantly transmits inhibitory impulses to the inspiratory center?
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Which center continually stimulates the inspiratory center unless inhibited?
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Which part of the brain is stimulated by pain, strong emotion, and movement and can either stimulate or inhibit pulmonary ventilation?
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What site is responsible for conscious control of pulmonary ventilation?
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What site is known for the anticipatory rise in pulmonary ventilation during exercise?
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What type of receptors in skeletal muscles and joints stimulate pulmonary ventilation during exercise?
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Match the following sensitivity functions:
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What does P/R represent?
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What is minute ventilation represented as?
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How is alveolar ventilation calculated?
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What is inspiratory capacity represented as?
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How is total lung capacity calculated?
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What does functional residual capacity consist of?
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What is vital capacity calculated as?
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What does Pb * Fg represent?
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How is percent saturation of blood with oxygen calculated?
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What does aO2 - Vo2 represent?
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Study Notes
Dead Space in the Respiratory System
- Anatomical Dead Space: Composed of the conducting zone; no gas exchange; includes areas without capillary blood supply.
- Physiological Dead Space: Combination of anatomical dead space and alveoli without blood supply.
Airflow Dynamics
- Air flows in response to pressure gradients overcoming resistance.
Composition of Atmospheric Air
- Correct Composition: Atmospheric air is approximately 20.93% oxygen, 0.03% carbon dioxide, and 79.04% nitrogen.
Effects of Altitude on Oxygen Levels
- Percentage of oxygen in air remains consistent as altitude increases; barometric pressure decreases.
Hyperventilation and Breath Holding
- Hyperventilation does not effectively lengthen breath-holding time or significantly increase arterial oxygen partial pressure (PAO2).
Oxygen Transport in Blood
- Only 1.5-3% of oxygen is transported dissolved in blood plasma; this fraction is responsible for determining the blood's partial pressure of oxygen (PO2).
Hemoglobin and Blood Oxygen Saturation
- In arterial blood with a PO2 of 95 mmHg, hemoglobin saturation is approximately 97%.
Characteristics of Pulmonary Venous Blood
- Not all pulmonary venous blood is fully oxygenated under normal circumstances.
Respiration and Exercise Limitation
- Respiration does not serve as a major limiting factor in exercise for healthy, moderately fit individuals.
Ventilation Response to Exercise
- Minute ventilation shows an initial rapid increase during exercise, maintained for about 20-30 seconds, followed by a gradual rise to a steady state.
Indicators of Internal Respiration
- The arterio-venous oxygen difference (a-vO2 diff) serves as a key indicator of internal respiration efficiency.
Workload and Ventilatory Thresholds
- Higher ventilatory thresholds correlate with greater endurance activity intensity that can be sustained.
Importance of PaO2 During Exercise
- Maintaining arterial oxygen (PaO2) during exercise is crucial for effective gas exchange, particularly regarding the oxygen transfer across the alveolar-capillary interface.
Altitude Training and Athletic Performance
- Athletes training at high altitudes can enhance performance in competitions at the same altitude shortly after training, with no consistent effect at sea level.
Neural Control of Respiration
- Dorsal Respiratory Group: Originates impulses to stimulate inspiratory muscles.
- Ventral Respiratory Group: Maintains inspiratory tone and stimulates expiratory muscles.
Impulse Regulation in Respiration
- Pneumotaxic Center: Transmits inhibitory signals to the inspiratory center and plays a role in regulating breathing rhythm.
- Apneustic Center: Continuously stimulates the inspiratory center unless inhibited.
Influence of Emotions on Ventilation
- The hypothalamus can stimulate or inhibit pulmonary ventilation based on factors like pain or strong emotions.
Conscious Control of Breathing
- The cerebral cortex is responsible for voluntary control of pulmonary ventilation; however, it is overridden by high PCO2 levels.
Anticipatory Responses in Exercise
- The cerebral cortex also initiates an anticipatory rise in ventilation rates before exercise begins.
Mechanoreceptors and Exercise Adaptations
- Proprioceptors in muscles and joints stimulate increased pulmonary ventilation during physical activity.
Chemoreceptors and Ventilation
- Central Chemoreceptors: Sensitive to rising PCO2 and decreasing pH, stimulating ventilation.
- Peripheral Chemoreceptors: Responsive to low PO2 and high potassium (K) levels; also stimulate ventilation.
Key Respiratory Equations
- Air Flow (P/R): Represents the relationship between pressure and resistance in airflow.
- Minute Ventilation (Vt * F): Calculated by multiplying tidal volume (Vt) by breathing frequency (F).
- Alveolar Ventilation ((Vt-Vd) * F): Quantity of fresh air reaching alveoli, incorporating dead space (Vd).
- Inspiratory Capacity (IRV + Vt): Total volume of air that can be inspired after normal expiration.
- Total Lung Capacity (IRV + Vt + ERV + RV): Overall lung volume encompassing all air in the lungs.
- Functional Residual Capacity (ERV + RV): Volume of air remaining in the lungs after normal exhalation.
- Vital Capacity (IRV + Vt + ERV): Total volume of air that can be exhaled after maximal inhalation.
- Partial Pressure of a Gas (Pb * Fg): The fraction of total pressure contributed by a specific gas.
- Percent Saturation of Blood with Oxygen ((Hb combined with O2 / Hb capacity to combine with O2) * 100): Measures how much oxygen is bound to hemoglobin relative to its maximum capacity.
- A-vO2 Difference (aO2 - Vo2): Indicates the difference in oxygen content between arterial and venous blood, reflecting oxygen use by tissues.
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Description
Test your knowledge of key concepts in Chapter 9 of Physiology. This quiz focuses on the definitions and distinctions related to the respiratory system, including anatomical and physiological dead space. Perfect for anyone looking to solidify their understanding of respiratory mechanics.
