Chapter 2 -- Ventilation
Inspired air that reaches the alveoli.
Out pouching of lung tissue through which gas exchange between alveolar air and pulmonary capillary blood takes place.
Complete absence of spontaneous ventilation.
760 mmHg (universal).
Short episodes of rapid, uniformly deep inspiration followed by 10-30 seconds of apnea.
Volume of gas is inversely proportional to its pressure at constant temperature.
- Inspiration -- diaphragm contracts; volume increases and pressure decreases (757 mmHg)
- Expiration -- diaphragm relaxes; volume decreases and pressure increases (763 mmHg)
10-30 seconds of apnea followed by a gradual increase in the volume and frequency of breathing
Dead space ventilation
Inspired air that does not reach the alveoli.
Volume increases and pressure decreases (757 mmHg).
Pressure difference between two points in a tube or vessel.
Difficulty breathing, of which the individual is aware.
Portion of a ventilatory cycle at which expiration stops.
Portion of a ventilatory cycle at which inspiration stops.
Normal, spontaneous breathing.
When the diaphragm relaxes, the alveolar pressure rises to 763 mmHg.
Always moves from a high-pressure area to a low-pressure area.
Increased depth of breathing with or without an increased frequency.
Increased alveolar ventilation.
1. Diaphragm contracts.
2. Thorax expands.
3. Trans-respiratory changes from 0 to +3.
4. Inspiration occurs.
5. Alveolar pressure continues to rise as the alveoli fill with air.
6. Once the alveolar pressure reaches 760 mmHg again, inspiration ends.
7. Thorax recoils.
8. Diaphragm relaxes.
9. Alveolar pressure continues to rise as the lungs and the thorax recoil on the alveoli.
10. This pressure gradient causes gas to flow out of the lungs.
11. Expiration begins.
Mechanisms of pulmonary ventilation
- During inspiration, barometric pressure is greater than alveolar pressure
- During expiration, alveolar pressure is greater than barometric pressure
Patient is comfortable breathing in an upright position.
Phases of ventilation
Purpose of transrespiratory pressure
Causes airflow into and out of the lungs.
Rapid rate of breathing.
Three types of dead space
Volume of air that moves into and out of the lungs in one quiet breath.
Difference between atmospheric and alveolar pressure.
Difference between alveolar and pleural pressure.
Results from a pressure gradient in the trans-respiratory pressure.