During strenuous exercise, why does the ventilation-perfusion ratio (V/Q) mismatch sometimes lead to arterial hypoxemia despite increased alveolar ventilation?

💡 Explanation

Hypoxemia can occur during intense exercise because the increased cardiac output reduces the time red blood cells spend in alveolar capillaries. The diffusion limitation across the alveolar-capillary membrane may not allow complete oxygen saturation, therefore, hypoxemia arises rather than full saturation, due to reduced transit time for gas exchange and mismatched V/Q.

• Why does an aging eye lose near focus accommodation, impacting lens curvature?
• If a marathon runner experiences a sudden inability to maintain pace despite adequate glycogen stores, which failure mode primarily explains this phenomenon, considering peripheral fatigue mechanisms?
• Why does a drug that inhibits acetylcholinesterase at the neuromuscular junction cause sustained muscle contraction, rather than a normal cycle of contraction and relaxation?
• Why does consuming large quantities of poorly digestible plant fiber lead to increased gas production and bloating in the digestive tract?
• If a growth factor receptor mutation in cancer cells disables the intrinsic apoptosis pathway while nutrient supply decreases, which consequence follows?
• Which mechanical limitation results when systemic vascular resistance severely drops suddenly?