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Thursday, December 1, 2011

Functions of the lungs

The lungs serve three functions.  Can you name them?  If not don't worry because I will name them here.

1.  Respiration:  Oxygen inhaled and carbon dioxide exhaled
2.  Reservoir for the left ventricle:  Pulmonary circulation is a blood reservoir for the left ventricle.  Even when cardiac output changes this reservoir volume remains constant (about 600 ml)
3.  Filter for systemic circulation:  Pulmonary circulation filters particles and prevents them from getting to the systemic circulation and causing blockages, particularly blockages in capillaries in the heart and brain.  Filtered particles include:

  • Fibrin
  • Blood clots
  • Fat cells
  • Platelet aggregates
  • Debris found stored blood
  • Debris found in IV fluids
4.  Metabolism:  Mainly of bioactive substances
5.  Storage and synthezising:  Of Heparin, histamine, bradykinin, serotonin and certain prostaglandins 
6.  Conversion:  Angiotensin converted to its active form by the lungs
7.  Inactivation:  Adenosine Triphosphate (ATP) adn norepinephrine are partially removed from blood and inactivated by the lungs.

The later two functions are particularly important to maintaining homeostasis.

Source:  Egan: Fundamentals of Respiratory Care


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