Overview Oxygen-hemoglobin dissociation curve sigmoidal shape is characteristic of positive cooperativity binding of 1 O2 molecule to 1 subunit of deoxyhemoglobin increases affinity for O2 in adjacent subunits P50 is PO2 at which hemoglobin is 50% saturated ↑ P50 → ↓ hemoglobin affinity for O2 50% saturation achieved at higher-than-normal P50 ↓ P50 → ↑ hemoglobin affinity for O2 50% saturation achieved at lower-than-normal P50 Loading and unloading of oxygen in lungs PaO2 ≈ 100 mm Hg hemoglobin % saturation ≈ 100% facilitates maximal O2 loading into arterial blood in lungs in peripheral tissues PvO2 ≈ 40 mm Hg hemoglobin % saturation ≈ 75% facilitates O2 unloading into peripheral tissues Shift to right mechanism ↑ P50 → ↓ hemoglobin affinity for O2 → ↑ O2 unloading causes ↑ PCO2, ↓ pH (Bohr Effect) ↑ PCO2 → ↑ H+ → ↓ pH CO2 + H2O → H2CO3 → H+ + HCO3- ↑ PCO2 → equilibrium reaction shifts right Le Chatelier's principle ↑ CO2, ↑ H+ bind hemoglobin and stabilize low O2 affinity T (taut) state ↓ hemoglobin affinity for O2 → ↑ O2 unloading e.g., exercise → ↑ PCO2, ↓ pH ↑ O2 unloading ensures O2 delivery meets O2 demand in skeletal muscle ↑ temperature e.g., ↑ tissue metabolism → ↑ temperature ↑ 2,3-bisphosphoglycerate (2,3-BPG) high altitude → hypoxemia → ↑ synthesis of 2,3-BPG Also seen in heart failure, anemia, morbid obesity, etc. ↑ 2,3-BPG binds hemoglobin and stabilizes low O2 affinity T (taut) state ↓ hemoglobin affinity for O2 → ↑ O2 unloading Shift to left mechanism ↓ P50→ ↑ hemoglobin affinity for O2 → ↓ O2 unloading causes ↓ PCO2, ↑ pH (Bohr Effect) ↓ PCO2 → ↓ H+ → ↑ pH ↓ CO2, ↓ H+ → stabilizes high O2 affinity R (relaxed) state ↑ hemoglobin affinity for O2 → ↑ O2 loading conversely, ↑ O2 decreases Hb affinity for CO2/H (Haldane effect) ↓ temperature ↓ tissue metabolism → ↓ temperature ↓ 2,3-bisphosphoglycerate (2,3-BPG) hemoglobin F fetal hemoglobin 2 α subunits and 2 γ subunits (α2γ2) ↑ affinity for O2, ↓ affinity for 2,3-BPG facilitates O2 delivery from mother to fetus
QUESTIONS 1 of 1 1 Previous Next (M1.PL.14.25) A 67-year-old male is brought in by EMS after being found unconscious on the first floor of a burning building. On exam, his respiratory rate is 14 breaths/min with scattered wheezes. He has no evidence of any burns, but dark soot is caked around much of his face (see Figure A). Suspecting inhalational injury, you expect this man's oxygen-hemoglobin curve will be: QID: 100090 FIGURES: A Type & Select Correct Answer 1 Unchanged, due to the fact that carbon monoxide (CO) is largely unbound and dissolved in plasma 1% (1/165) 2 Shifted right, due to strong competition between CO and O2 for binding 18% (29/165) 3 Shifted left, due to carbon monoxide binding 72% (118/165) 4 Shifted left, due to metabolic acidosis in tissues 2% (4/165) 5 Shifted right, due to decreased affinity for oxygen 5% (8/165) M 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic
All Videos (2) Login to View Community Videos Login to View Community Videos Bohr and Haldane Effects Keshav Mudgal Respiratory - Oxygen-Hemoglobin Dissociation Curve D 10/29/2015 81 views 5.0 (2) Login to View Community Videos Login to View Community Videos Oxygen-Hemoglobin Dissociation Curve Respiratory - Oxygen-Hemoglobin Dissociation Curve D 2/14/2015 116 views 5.0 (4) Respiratory | Oxygen Hemoglobin Dissociation Curve Respiratory - Oxygen-Hemoglobin Dissociation Curve Listen Now 9:45 min 1/31/2023 6 plays 0.0 (0)