Why Does a Lung Air Sac Need Both Airflow and Blood Flow?

READ THE IMAGE

What the illustration shows

Medical poster titled Two Supplies for Lung Exchange. An opened cluster of alveoli connects to an airway. Gold double-headed arrows in the airway and airspaces represent ventilation. Red blood cells and burgundy flow arrows stay inside a surrounding capillary network, representing perfusion. Labels identify alveolar airspace and capillary. A lower enlargement places airspace left and capillary blood right across an intact wall. An oxygen arrow points toward blood and a carbon dioxide arrow toward airspace. Text distinguishes air delivery from blood delivery. Simplified, not-to-scale illustration with gold AllHumanBody.com branding.

How to interpret this poster

• Cluster shape, capillary layout, colors and wall thickness are schematic, not measured microanatomy.
• Oxygen arrow indicates the bloodward direction at the wall; neither arrow measures diffusion rate or molecular scale.
• No universal ventilation/perfusion ratio, equal-volume rule, clot, treatment or oxygen-free blue-blood claim.
• AI-assisted educational illustration; not physician certification, microscopy, a diagnosis or individualized medical advice.
• Fine annotations need enlargement; the full description provides an accessible text alternative.
• Display the full uncropped illustration; do not trim titles, legends or boundary annotations.

AI-assisted educational illustration, adapted into web-sized images without changing its composition. This is general education, not an individual diagnosis or treatment recommendation.

EVIDENCE / CONTEXT

Sources and what they support

1. Anatomy and Physiology 2e: 22.4 Gas Exchange ↗

   Ventilation/perfusion distinction and external gas-exchange direction; preserved direct paragraph 74–76 and production external-respiration reread.