Transport of Oxygen — Prelims Strategy

Prelims Strategy

To excel in NEET questions on oxygen transport, a multi-faceted strategy is essential. \n\n1. Master the Oxygen-Hemoglobin Dissociation Curve (ODC): Understand its sigmoidal shape, the significance of the plateau and steep portions, and the $P_{50}$ value.

Practice drawing and interpreting the curve. \n2. Memorize Key Factors for Shifts: Create a clear mental map or mnemonic for factors causing rightward shifts (increased $pCO_2$, decreased pH, increased temperature, increased 2,3-BPG) and leftward shifts (opposite conditions, plus fetal hemoglobin).

Understand *why* these shifts occur physiologically (e.g., Bohr effect for $CO_2$/pH, 2,3-BPG for hypoxia). \n3. Understand Partial Pressures: Know the approximate $pO_2$ values in the alveoli, arterial blood, venous blood, and resting tissues.

This helps in understanding the direction of oxygen diffusion and hemoglobin saturation levels. \n4. Quantitative Aspects: Remember the oxygen carrying capacity (approx. 20 mL $O_2$ per 100 mL blood) and the binding capacity of hemoglobin (1.

34 mL $O_2$ per gram of Hb). Be prepared for simple calculations. \n5. Distinguish Transport Forms: Know the percentages of oxygen transported dissolved in plasma vs. bound to hemoglobin. \n6. Practice Scenario-Based Questions: Many NEET questions are application-based.

Think about how oxygen transport changes during exercise, at high altitude, or in conditions like acidosis. \n7. Avoid Common Traps: Be careful not to confuse right shift with increased affinity, or vice versa.

Remember that a right shift means *decreased* affinity and *increased* oxygen release to tissues. Also, distinguish between oxygen loading in the lungs and unloading in the tissues. \n8. Comparative Study: Always compare oxygen transport with carbon dioxide transport, noting similarities and differences in carriers, binding sites, and regulatory effects (Bohr vs.

Haldane effect).