Transport of Oxygen and Carbon Dioxide. How Gases Are Transported. Introduction. To explore how O2 is transported in the blood. To explore how Co2 is transported in the blood. This will include understanding the oxygen dissociation curve. . What you need to know
How Gases Are Transported
Haemoglobin molecules can transport up to four O2’s
Co-operative binding: haemoglobin’s affinity for O2 increases as its saturation increases.
When 4 O2’s are bound to haemoglobin, it is 100% saturated, with fewer O2’s it is partially saturated.
Oxygen binding occurs in response to the high PO2 in the lungs
Haemoglobin saturation is determined by the partial pressure of oxygen. When these values are graphed they produce the Oxygen Disassociation Curve
In the lungs the partial pressure is approximately 100mm Hg at this Partial Pressure haemoglobin has a high affinity to 02 and is 98% saturated.
In the tissues of other organs a typical PO2 is 40 mmHg here haemoglobin has a lower affinity for O2 and releases some but not all of its O2 to the tissues. When haemoglobin leaves the tissues it is still 75% saturated.
Lungs at sea level: PO2 of 100mmHg haemoglobin is 98% SATURATED
Lungs at high elevations: PO2 of 80mmHg, haemoglobin 95% saturated
When the PO2 in the lungs declines below typical sea level values, haemoglobin still has a high affinity for O2 and remains almost fully saturated.
Even though PO2 differs by 20 mmHg there is almost no difference in haemoglobin saturation.
increased blood temperature
reduces haemoglobin affinity for O2
hence more O2 is delivered to warmed-up tissue
Respiratory Response to ExerciseFactors affecting Disassociation
CARBON DIOXIDE CONCENTRATION
Each of these conditions can reflect increased local oxygen demand. They increase oxygen uploading in the needy area.
3) Haemoglobin is usually about 98% saturated with oxygen. This reflects a much higher oxygen content than our body requires, so the blood’s oxygen-carrying capacity seldom limits performance.
4) Carbon dioxide is transported in the blood primarily as bicarbonate ion. This prevents the formation of carbonic acid, which can cause H+ to accumulate, decreasing the pH. Smaller amounts of carbon dioxide are carried either dissolved in the plasma or bound to haemoglobin