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Figure 10.9 The respiratory cycle. Regulation of Breathing. Figure 10.13. Respiratory centers in the pons and medulla oblongata control b oth the rate of respiration and the inspiratory depth. Higher brain centers, in the cerebrum, have conscious control, and can modify breathing. - PowerPoint PPT Presentation
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Copyright © 2009 Pearson Education, Inc.
Figure 10.9 The respiratory cycle.
Regulation of Breathing
Figure 10.13
• Respiratory centers in the pons and medulla oblongata control both the rate of respiration and the inspiratory depth.
• Higher brain centers, in the cerebrum, have conscious control, and can modify breathing.
• Medulla oblongata: sensitive to hydrogen ions (pH) in cerebrospinal fluid resulting from carbon dioxide in blood
• Carotid and aortic bodies: sensitive to oxygen and hydrogen ion (pH) levels
Regulation of Breathing
Carbon dioxide & pH
• Carbon dioxide is a waste product in exhaled air
• Forms an acid in water:
CO2 + H2O carbonic acid (H2CO3)
H2CO3 bicarbonate (HCO3-) + hydrogen ion (H+)
• pH is a measure of the hydrogen ion concentration
• The carbonic acid–bicarbonate buffer system (like all buffers) resists pH changes.
• If H+ concentrations in blood begin to rise, excess H+ is removed by combining with HCO3
– .
• If hydrogen ion concentrations begin to drop, H2CO3 dissociates, releasing H+
The bicarbonate buffer system in blood
Copyright © 2009 Pearson Education, Inc.
Figure 10.12 oxygen transport in blood.
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Figure 10.12 carbon dioxide transport in blood.
Copyright © 2009 Pearson Education, Inc.
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Figure 10.10a Measurement of lung capacity.
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Figure 10.10a Measurement of lung capacity.
Respiratory Volumes• Tidal volume (TV) – air that moves into and out
of the lungs with each breath (approximately 500 ml)
• Inspiratory reserve volume (IRV) – air that can be inspired forcibly beyond the tidal volume (2100–3200ml)
• Expiratory reserve volume (ERV) – air that can be evacuated from the lungs after a tidal expiration (1000-1200ml)
• Residual volume (RV) – air left in the lungs after strenuous expiration (1200ml)
Respiratory Capacities
• Vital capacity (VC) – the total amount of air that can be taken in by the deepest expiration followed by the deepest inspiration
= TV + ERV + IRV
• Total lung capacity (TLC) – sum of all lung volumes = VC + Residual Volume (approximately 6000 ml in males)
Other Pulmonary Function Tests
• Forced vital capacity (FVC) – gas forcibly & rapidly expelled after taking a deep breath
• Forced expiratory volume (FEV = peak flow) – the amount of gas expelled during specific time intervals (usually 1 sec)
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Figure 10.11 Partial pressures. (1 of 3)
