Respiratory system 3

Respiratory system 3

1. Lungs

   • Apex points superiorly, extending into neck above 1st rib
   • Base rests on superior surface of diaphragm
   • Costal surface: follows contours of rib cage
   • Mediastinal surface: contains hilum, bears grooves of great BVs and cardiac impression
   • Right Lung
     • Right pleural cavity
     • 3 lobes: superior, middle, inferior
     • Horizontal and Oblique fissures
     • Broader than left lung
     • Shorter than left lung (diaphragm rises on right side to accommodate liver
   • Left Lung
     • Left pleural cavity
     • 2 lobes: superior and inferior
     • Narrower than right lung ( heart and great vessels project into left pleural cavity (cardiac notch and cardiac impression
     • Longer than right lung

2. Pleura and pleural cavity

   • Parietal pleura: covers diaphragm and thoracic wall
   • Visceral Pleura covers outer surfaces of lungs
   • Between pleura is pleural cavity
     • Filled with pleural fluid secreted by both pleural membranes - lubrication = prevention of friction during breathing

3. Clinical examples

   • Pnemumothorax
   • Haemothorax
   • Chylothorax
   • Pleural effusion
   • Thiracocentesis
   • Pleuritis (Pleurisy)

4. Thoracic cage

   • True ribs (vertebrosternal ribs) : 1-7
   • False ribs: Vererbrochondral ribs: 8-10 and Floating ribs (vertebral ribs) 11+12

5. Intercostal muscle

   • Assist breathing by changing dimensions of rib cage
   • External intercostal muscles - inspiration
   • Internal and innermost intercostal muscles - forced expiration
   • Elastic recoil of lungs - adequate for passive expiration

6. Diaphragm

   • Between thoracic and abdominal cavities
   • Dome-shaped skeletal musle
   • Inspira5tion- diaphragm contracts and moves inferiorly, increases thoracic volume and causes air to be drawn into lungs
   • Expiration - diaphragm relaxes and air pushed out of lungs