Gas Exchange Regulation of Respiration Dr.Khaled Helmy

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

Conducting Zone Structures Primary bronchi Secondary bronchi Tertiary bronchi Conduits to and from respiratory zone, no gas exchange occurs Slide 13.16 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Respiratory Zone Structures Site of gas exchange Respiratory bronchioles Alveolar duct Alveoli Site of gas exchange

Respiratory Membrane                              <>

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

External Respiration The alveoli always has more oxygen than the blood                                                                <> 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)

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)

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

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

External and Internal Respiration Figure 13.11 Slide 13.34b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

External Respiration, Gas Transport, and Internal Respiration Summary Figure 13.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Neural Regulation of Respiration

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

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

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