Upper Lung Zones and TB

Upper and mid lung field distribution
Ashley Davidoff MD TheCommonvein.net lungs-0772

  • Upper Lobes are the Largest Lobes
  • TB typically affects the upper lobes of the lungs first, as this area has a higher oxygen concentration and is more favorable to bacterial growth.
  • TB bacteria require oxygen to survive and multiply, and the upper lobes have a higher oxygen supply than the lower lobes of the lungs.
  • upper lobes have a larger surface area and better ventilation, which allows the bacteria to more easily enter and spread within the lung tissue.
  • Finally, the lymphatic drainage from the upper lobes also contributes to the increased vulnerability of this area to TB infection.
  • The lymphatic drainage of the upper lobes and lower lobes of the lungs differs
    • In the upper lobes
      • lymphatic drainage is more extensive and interconnected
      • because the
        • upper lobes contain a
          • larger number of lymph nodes
          • lymphatic vessels in the upper lobes also tend to be
            • larger and
            • more numerous and therefore
              • more efficient circulation of lymphatic fluid.
          • the lower lobes of the lungs
            • limited lymphatic drainage system,
            • fewer lymph nodes and
            • smaller lymphatic vessels.