Respiratory

• Alveoli increase surface area for gas exchange
• Surfactant is what covers alveoli and lowers its surface tension
• In pulmonary arteries, blood is O2 poor and CO2 rich
• In pulmonary veins, blood is O2 rich and CO2 poor
• In arteries, blood is O2 rich and CO2 poor
• In veins, blood is O2 poor and CO2 rich
• This is thoracic cavity

  A) parietal pleura

  B) visceral pleura

  C) pleural cavity

  
• Normal human inhalation is accomplished through negative-pressure breathing
• During inhalation, diaphragm contacts down, external intercostal muscles contract up and out, which increases volume in lungs and decreases lung pressure, causing air to go in
• During exhalation, diaphragm and external intercostal muscles relax, which decreases volume in lungs, increases pressure there, causing air to move out
• Forced exhalation happens due to contraction of internal intercostal muscles
• HCO3 is exchanged with Cl- in RBC
• CO2 is transformed into carbonic acid by the enzyme carbonic anhydrase
• Carbonic acid dissociates into H+ and HCO3-
• The H+ binds to hemoglobin (decreasing pH)