Respiratory: Oxygen transport in the blood Flashcards
How do you calculate how much dissolved O2 conc?
Solubility coefficient x pO2
What are the 2 oxygen binding pigments?
Hb - in blood, binds 4 O2 molecules
Myoglobin - in muscles, binds 1 O2 molecule
How low can pO2 get in the tissues?
pO2 must be high enough to drive diffusion of O2 into cells - must not fall below 3kPa
(however the higher the capillary density the lower this can fall)
What is the Bohr shift?
The Bohr shift shifts the Hb dissociation curve to the right
- pH causes a shift (acidic conditions)
- temp causes the shift (warmer conditions)
pH is lower and temp is higher in the most metabolically active tissues so extra O2 is given up
What is the effect of 2,3 -BPG on Hb?
What factors affect concentrations of 2.3-BPG?
Shifts the dissociation curve to the right and allows more O2 to be given up at the tissues.
2,3-BPG increases at altitude and with anaemia
2,3-BPG decreases at refrigeration
What is cyanosis?
A blueish colour of skin and mucous membranes due to unsaturated Hb.
Can be peripheral due to poor local circulation or central (mouth, tongue, lips) due to poorly saturated Hb in systemic circulation.
How does pulse oximetry work and what does it measure?
Pulse oximetry detects level of Hb saturation by measuring the difference in the absorption of light between oxy and deoxy Hb in arterial blood.
It measures the saturation however doesnt measure how much Hb is present.
