The Human Respiratory System

1. The Human Respiratory System

2. Muscles involved in breathing • Diaphragm • Intercostal muscles – muscles between the ribs • Neck muscles – raise sternum and upper ribs

3. Interpleural fluid • Fluid inside the thoracic cavity • Water molecules cause the lungs to stick to the thoracic wall • Helps the lungs expand when you inhale

4. Inhaling • Active process (requires energy) • http://teachhealthk-12.uthscsa.edu/studentresources/AnatomyofBreathing3.swf • Diaphragm – contracts • Flattens and moves down • Intercostal muscles – contract • Move rib cage up and out • Volume of thoracic cavity - increases

5. Exhaling • Passive process • http://teachhealthk-12.uthscsa.edu/studentresources/AnatomyofBreathing3.swf • Diaphragm – relaxes • Moves up • Intercostal muscles – relax • Rib cage moves down • Volume of thoracic cavity - decreases

6. Air Pressure • Atmospheric pressure – pressure of the air in the atmosphere • Intrapleural pressure – pressure of the air inside the pleural cavity (area around the lungs) • Intrapulmonary pressure – pressure of the air inside the alveoli

7. 760 754 759 Inhaling • Volume increases • Intrapleural pressure decreases • Intrapulmonary pressure decreases • Air moves with the pressure gradient and moves into the lungs and alveoli

8. 760 756 761 Exhaling • Volume decreases • Intrapleural pressure increases slightly (lower than atmospheric pressure) • Intrapulmonary pressure increases • Air moves with the pressure gradient and moves out of the alveoli