XI: Gas Transport Flashcards
Why does blood reach left atrium at 95mmHg instead of 105mmHg?
Because of drainage of bronchial circulation and mixture of blood from different ventilation areas
PCO2 is always 40mmHg except
When it leaves the tissues at 45mmHg
Blood reaching the tissues with a PO2 of
95mmHg
Why are pressure differences smaller for CO2
Due to a greater diffusion capacity
How much oxygen is dissolved in blood
3%
How much oxygen bound to Hb
97%
In situations of high PO2, O2 binds or dissociates from Hb
Binds
In situations of low PO2 is dissociates from Hb
Hb saturation when leaving capillaries, leaving lungs and tissues
Capillaries - 100%
Lungs - 98%
Tissues - 75%
How much O2 mL dissolved for every 100mL of blood
0.3mL of O2
Venous level saturation during exercise
Decreases because we need to get more O2 to tissues
1st step for exchange
Partial pressure have to be equalized to 100mmHg
What happens after partial pressures have been equalized,
Hb from deoxeginated oxygen binds to O2
Partial pressure equalization in tissues process
Partial pressure first equalized, then O2 dissociates and Hb becomes less saturated
PO2 at 100mmHg at
100% Hb saturation
PO2 at 95mmHg at
98% Hb saturation
PO2 at 40mmHg at
75% Hb saturation
Relationship of Hb dissociation curve is
Sigmoidal
At P50
50% saturation –> 26/27mmHg
At P90
90% saturation –> 60mmHg
Curve has 2 parts (horizontal and vertical)
Horizontal part where changes in pressure do not lead to large changes in saturation
Vertical part where large changes in pressure lead to great changes in saturation
Factors impacting O2-Hb dissociation curve
Temperature
PCO2
2-3,DPG
pH
Factors increasing Hb affinity for O2
Decreased temperature
Decreased PCO2
Decreased 2,3-DPG
Increased pH
Factors decreasing Hb affinity for O2
Increase temperature
Increase PCO2
Increase 2,3-DPG
Decrease in pH
