oxygen dissociation curve

oxygen dissociation curve

graphic expression of the affinity of hemoglobin for oxygen as a function of the partial pressure of oxygen. Dissociation is influenced by pH, temperature, and carbon dioxide pressure. Formerly called oxyhemoglobin dissociation curve.

oxygen dissociation curve

Oxygen saturation curve Physiology A curve that describes the relationship between Hb O2 saturation and tension; defined by a sigmoid curve which reflects the interaction of the 4 Hb molecules involved in O2 uptake, transport and release; a 'right shift' of the curve indicates ↓ Hb affinity for O2, as occurs in ↓ pH–ie, acidosis, ↑ temperature, ↑ PCO2, while a 'left shift' indicates ↑ O2 affinity with ↑ pH, ↓ temperature, ↓ 2,3 DPG and ↓ PCO2 Right shifts Acidosis, hyperthermia, alveolar hypoventilation, anemia Left shifts Alkalosis, hypothermia, hyperventilation, carboxyhemoglobinemia, hypophosphatemia, ↑ fetal Hb. See 2,3 DPG.
Oxygen dissociation curveclick for a larger image
Fig. 242 Oxygen dissociation curve .The characteristic S-shaped curve of oxygen dissociation.

oxygen dissociation curve

a curve derived from plotting the percentage saturation of blood with oxygen, against the oxygen tension (the oxygen exchange).

The curve is S-shaped and shows that HAEMOGLOBIN has a high affinity for oxygen.Blood can become saturated at relatively low oxygen tensions, but a small drop in oxygen tension brings about a big fall in the saturation of the blood. If tissues use up oxygen, then haemoglobin responds by giving it up.

Where CO2 is present, haemoglobin has to be under higher oxygen tension in order to become fully saturated. However, under these circumstances it releases O2 at higher oxygen tensions. CO2 affects the efficiency of oxygen uptake by haemoglobin but increases its efficiency in releasing it. The oxygen-carrying capacity of blood is also affected by pH (see BOHR EFFECT).

References in periodicals archive ?
On this occassion I also would like to emphasize that methylenblue (1-2 mg/kg in 1% solution; in higher concentration and doses causes and or increases methemoglobinemia) should be preferred in acquired as well as hereditary enzymopenic methemoglobinemias, since it is effective within minutes with corrected oxygen dissociation curve.
50] indicates a rightward shift in the oxygen dissociation curve, i.
A hemoglobin such as hemoglobin Venusberg has an alteration that leads to lower oxygen affinity and thus a right-shifted oxygen dissociation curve.
Second, methemoglobin results in a leftward shift of the oxygen dissociation curve causing normal hemoglobin to bind oxygen more tightly and preventing the oxygen from unloading freely at the peripheral tissues (8).
3+] ferric haems paradoxically exhibit increased oxygen affinity, causing the oxygen dissociation curve to be shifted 'to the left', which further impairs oxygen delivery to the tissues (Fig.
This is known as cooperative binding, and is the reason for the sigmoid shape of the oxygen dissociation curve.
In contrast to myoglobin, which has a hyperbolic oxygen dissociation curve and 50% saturation at 1 torr oxygen pressure, Hb has a sigmoidal dissociation curve and 50% saturation at 26 torr.
The oxygen dissociation curve of normal hemoglobin represents the reaction of hemoglobin with oxygen as modified by hydrogen ions (Bohr effect) and 2,3-bisphosphoglycerate (BPG) (30, 31).
Second, the presence of methaemoglobin shifts the haemoglobin oxygen dissociation curve to the left and thereby further impairs oxygen delivery to the tissues.
This haemoglobin polymer has an oxygen dissociation curve that is right-shifted with a P50 of 43 mmHg, compared with 27 mmHg for human haemoglobin.
Oxygen binds cooperatively to Fe(II) hemoglobin, as depicted by the oxygen dissociation curve (ODC) shown in Fig.