1. Gas Exchange
Regulation of Respiration
Dr.Khaled Helmy

2. Gas Exchange Gas crosses the respiratory membrane by
Oxygen enters the blood
Carbon dioxide enters the alveoli

3. Conducting Zone Structures
Primary bronchi
Secondary bronchi
Tertiary bronchi
Conduits to and from respiratory zone, no gas exchange occurs
Slide 13.16
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4. Respiratory Zone Structures Site of gas exchange
Respiratory bronchioles
Alveolar duct
Alveoli
Site of gas exchange

5. Respiratory Membrane
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6. Gas Exchange Pulmonary gas exchange - in lungs
Oxygen (O2) moves into blood
Carbon dioxide (CO2) moves out of blood
Ventilation/perfusion matching
Pulmonary gas exchange - in lungs
Ventilation/perfusion matching
Pulmonary gas exchange - in lungs
Oxygen (O2) moves into blood
Carbon dioxide (CO2) moves out of blood
Gas Exchange
Pulmonary gas exchange - in lungs
Oxygen (O2) moves into blood
blood PO2 < alveolar PO2
Carbon dioxide (CO2) moves out of blood
blood Pco2 > alveolar Pco2
Ventilation/perfusion matching (V/Q)
Perfusion (blood flow) is matched to ventilation (air flow) in each group of alveoli

7. External Respiration The alveoli always has more oxygen than the blood
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The alveoli always has more oxygen than the blood
Oxygen moves by diffusion towards the area of lower concentration
Pulmonary capillary blood gains oxygen (moves from lung/alveoli to blood)

8. External Respiration (cont’d)
Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli
Pulmonary capillary blood gives up carbon dioxide
Blood leaving the lungs (pulmonary vein) is oxygen-rich and carbon dioxide-poor (coming in via pulmonary artery is opposite)

9. Oxygen Transport in the Blood
Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO2])
A small amount is carried dissolved in the plasma

10. Internal Respiration An opposite reaction to what occurs in the lungs
Carbon dioxide diffuses out of tissue to blood (concentration gradient)
In RBC’s quickly forms carbonic acid by combining with water
Carbonic acid breaks down via carbonic anhydrase creating bicarbonate ions
Oxygen diffuses from blood into tissue (concentration gradient)
Slide 13.34a

11. External and Internal Respiration
Figure 13.11
Slide 13.34b
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12. External Respiration, Gas Transport, and Internal Respiration Summary
Figure 13.10
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13. Neural Regulation of Respiration

14. Respiratory Disorders:
Bronchial asthma
Chronic bronchitis and emphysema
Lung fibrosis
Lung Cancer
Slide 13.40a

15. Aging Effects Elasticity of lungs decreases
Vital capacity decreases (decreased ability to inflate the lungs)
Blood oxygen levels decrease
Stimulating effects of carbon dioxide decreases (sleep apnea d/t hypoxia)
More risks of respiratory tract infection (decreased cilia and dust cell function)
Slide 13.48
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

16. Respiratory Rate Changes Throughout Life
Newborns – 40 to 80 respirations per minute
Infants – 30 respirations per minute
Age 5 – 25 respirations per minute
Adults – 12 to 18 respirations per minute
Rate often increases somewhat with old age
Slide 13.49
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings