Updated: 12/16/2016

Oxygen-Hemoglobin Dissociation Curve

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Overview 
Oxygen-Hemoglobin Dissociation Curve
  • 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)
        • ↑ PCO→ ↑ H+ → ↓ pH
          • CO2 + H2 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
        • 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)
        • ↓ PCO→ ↓ 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
 

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Questions (1)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
Calculator

(M1.PL.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: Review Topic

QID: 100090
FIGURES:
1

Unchanged, due to the fact that carbon monoxide (CO) is largely unbound and dissolved in plasma

0%

(0/25)

2

Shifted right, due to strong competition between CO and O2 for binding

24%

(6/25)

3

Shifted left, due to carbon monoxide binding

52%

(13/25)

4

Shifted left, due to metabolic acidosis in tissues

8%

(2/25)

5

Shifted right, due to decreased affinity for oxygen

4%

(1/25)

M1

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