Diffusion across the alveolar membrane follows Vgas∝T Emphysema destroys surface area ; fibrosis and edema thicken ; supplemental oxygen raises the pressure gradient to compensate.
Ventilation, gas exchange, and respiratory regulation
How can I study Respiratory System effectively?▾
Start by reading the study notes and working through the examples on this page. Then use the flashcards to test your recall. Regular review and active practice are key to retention.
Is this Respiratory System study guide free?▾
Yes — all study notes, flashcards, and practice problems for Respiratory System on Study Mondo are free to access. No account is needed.
What course covers Respiratory System?▾
Respiratory System is part of the MCAT Prep course on Study Mondo, specifically in the Biological & Biochemical Foundations section. You can explore the full course for more related topics and practice resources.
A⋅D⋅(P1−P2)
A
T
Alveolar PO2 is about 100 mmHg vs. 40 mmHg in venous blood, driving oxygen loading.
Oxygen and Carbon Dioxide Transport
About 98.5 percent of O2 rides hemoglobin; cooperative binding makes the dissociation curve sigmoidal — a flat loading plateau in the lungs and a steep unloading region in tissues (P50≈26 mmHg).
Bohr effect: high CO2, low pH, heat, and 2,3-BPG right-shift the curve, releasing O2 where metabolism is high; fetal hemoglobin and CO shift it left.
CO2 travels mostly as bicarbonate via carbonic anhydrase: CO2 with the chloride shift preserving charge balance in RBCs.
Control of Ventilation
Central chemoreceptors in the medulla sense CSF pH as a proxy for arterial CO2 — the primary drive; peripheral chemoreceptors respond to PO2 below about 60 mmHg. Hyperventilation causes respiratory alkalosis; hypoventilation causes acidosis.
Key Takeaways
Fick's law variables map directly onto lung diseases.
Right shift releases oxygen; left shift hoards it.
Bicarbonate is the main CO2 vehicle, linked to acid-base balance.
CO2, not O2, is the master regulator of breathing.