- Saturation is the percentage of Hb-binding sites occupied by O2.
- oxygen capacity of Hb in blood is approximately 20 mL O2/100 mL of blood or 20 vol%. (MCQ)
- Each gram of Hb has an oxygen capacity of 1.34 mL O2, (MCQ)
- 100 mL of blood contains 15 g Hb
- completely oxygenated blood contains approximately 20 mL O2/100 mL (1.34 mL O2 × 15 g Hb/100 mL).
- Physiologic implications of the oxyhemoglobin dissociation curve
- Hb combines rapidly and reversibly with O2 to form oxyhemoglobin.
- The saturation curve has a sigmoid shape because oxygenation of the first
- heme group of the Hb molecule increases the affinity of O2 for the other
- heme groups.
The O2 capacity
- maximum amount of O2 that can be bound to Hb
- determined by the Hb concentration in blood.
- The O2 content
- total amount of O2 carried in the blood whether bound or dissolved in solution.
- Several factors influence the oxyhemoglobin dissociation curve
- Shifts to the right (MCQ)
- occur when the affinity of Hb-binding sites for O2 is decreased
- it is easier for tissues to extract oxygen.
- Causes of this shift include (MCQ)
- increased CO2 (Bohr effect)
- increased H+ (decreased pH)
- increased temperature
- increased 2,3-diphosphoglycerate (2,3-DPG).
- Anemia is characterized by a reduced Hb concentration in blood and decreased arterial oxygen content.
- Shifts to the left (MCQ)
- occur when there is increased affinity of Hb for O2
- it is more difficult for tissues to extract oxygen.
- Causes of this shift include(MCQ)
- decreased temperature
- decreased PCO2
- decreased H+ (increased pH),
- decreased 2,3-DPG.
- Stored blood loses 2,3-DPG and fetal Hb, and both decreases shift the curve to the left. (MCQ)
- Polycythemia is characterized by a higher than normal concentration of Hb in the blood, a shift to the left in the oxyhemoglobin dissociation curve, and increased arterial oxygen content. (MCQ)
- Shifts to the right (MCQ)
- Carbon monoxide poisoning
- Carbon monoxide (CO) has a much greater affinity (more than 200 times) for Hb than does O2. (MCQ)
- Thus, the amount if CO dissolved in plasma is essentially zero.
- The O2-binding capacity of Hb and the O2 content of blood decrease.
- The oxy hemoglobin dissociation curve shifts to the left. (MCQ)
- • Arterial PO2 is normal,but O2 saturation of Hb decreases.
- Saturation versus partial pressure.
- Each saturation curve has a single P50
- which is the PO2 that gives 50% saturation
- Normal P50 = 26 mm Hg (MCQ)
- O2 content versus partial pressure for two diffe ent hemoglobin (Hb) concentrations.
- Curve A represents normal Hb levels in blood (15 g/100 mL).
- Curve B represents a reduced concentration of Hb in blood (7.5 g/100 mL). The main effect of the lower Hb concentration is a reduced carrying ca- pacity of the blood.
- Thus, in curve B, the total amount of O2/100 mL of blood is around 10 mL O2/100 mL, instead of the normal 20 mL O2/100 mL. (MCQ)
Oxygen Hemoglobin Dissociation Curve Explained Clearly
Speaker: Roger Seheult, MD
Clinical and Exam Preparation Instructor
Board Certified in Internal Medicine, Pulmonary Disease, Critical Care, and Sleep Medicine.
060 Hemoglobin and the Oxygen-Dissociation Curve
n this episode, Leslie talks about how Hemoglobin transports oxygen. He also explains the oxygen dissociation curve and how that makes it easier to pick up and deliver oxygen when necessary.
Oxygen-Hemoglobin Dissociation Curve (USMLE)
A look at the 02-hg dissociation curve and its application; for the USMLE examinations
Hemoglobin vs Myoglobin: Oxygen Dissociation Curves
This video gives a brief overview on the Oxygen Dissociaton Curves for Hemoglobin and Myoglobin. It show’s the differing shapes of their curves, being sigmoidal/hyperbolic and thus the effects of being so.
Oxygen and Carbon Dioxide Dissociation Curves
This presentation will give a brief understanding on how to read and interpret oxygen and carbon dioxide dissociation curves. This video was created by a group of McMaster students in a knowledge translation course for the Demystifying Medicine series: Elizabeth Chan, Hannah Cho, Zainab Naimpoor, Rubaid Dhillon and Pavan Matharu.
AS PE – Oxygen Dissociation Curve & the Bohr Shift
Learn how haemoglobin works in the body.