Functions
The ventilation /perfusion ratio is higher at the apex of the lung, meaning more air reaches the apex than blood to carry it. paCO2 is decreased and paO2 increased in this area (similar findings to pulmonary embolism or emphysema, though not pathological).
Moderate exercise increases perfusion in the apical lung, hence increasing V/P ratio.
Anatomy
Rounded upper part of the lung, it extends into the neck, reaching 2.5 cm – 4 cm above level of the sternal end of the first rib. A sulcus, produced by the subclavian artery as it curves in front of the pleura, runs superiorly and laterally directly below the apex. It is positioned above the lobes and is partly responsible for filtering the air.
Clinical
Subtle differences in pathology compared to base of lung, due to heavier particles generally settling lower due to gravity. Pancoast tumours and Simon focuses are pathologies which appear at the lung apex.
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