PSC1002/L17 Transport of Gases in Blood Flashcards
How is oxygen transported in blood?
Bound to haemoglobin
What is the solubility of oxygen in plasma?
very low
At what PO2 is haemoglobin fully saturated?
100mmHg
At rest, what is the PO2 of arterial blood and tissue level?
Blood - 100mmHg
Tissue - 40mmHg
During exercise, what is the PO2 of arterial blood and tissue?
Blood - 100mmHg
Tissue - 15-40mmHg
What effect does CO2 have on the oxygen saturation curve? (2)
Shifts to right
Reduced affinity for O2
What effect does increased pH have on the oxygen saturation curve? (2)
Shift to left
Increased affinity for oxygen
Why does an increase in pH increase oxygen affinity? (2)
Decreased H+ bound to Hb
More O2 can bind to Hb
Describe the Bohr effect.
The reduction in oxygen affinity of haemoglobin when pH is low and increase in oxygen affinity when pH is high
What conformation of Hb does H+ binding favour?
T (tense) form
What effect does increased temperature have on the oxygen saturation curve? (2)
Shift to right
Reduced affinity for oxygen
Where is 2,3-BPG produced and what does it do? (3)
In erythrocytes
Interacts with B-chains of Hb
Improves O2 delivery to tissue which may otherwise be hypoxic
Give 3 conditions in which 2,3-BPG production is increased.
Chronic lung disease
Anaemia
Congestive heart failure
Lower atmospheric PO2 (altitude)
What is foetal haemoglobin composed of?
2a and 2y chains
What is the relative affinity of foetal Hb for oxygen? (2)
Stronger affinity than normal Hb
Foetal Hb takes up oxygen at PO2 values at which maternal Hb is releasing it
Give a pneumonic to remember the conditions which shift the oxygen saturation curve.
CADET
Carbon dioxide
Acid
Diphosphoglycerate
Exercise
Temperature
How is carbon dioxide transported in the blood? (2)
Bound to haemoglobin
As carbonic acid (70%)
What enzyme converts carbon dioxide into carbonic acid?
Carbonic anhydrase
What conformation does carbon dioxide binding promote in Hb?
Tense (T)
What is the name given to Hb bound to CO2?
Carbaminohaemoglobin
What is the relative affinity of carbon monoxide for Hb?
200x more than O2
What 2 effects does carbon monoxide binding to Hb have?
Limits O2 that Hb can carry - plateau of curve
Shifts Hb to relaxed conformation - shifts curve to left
Give a treatment oxygen for carbon monoxide poisoning.
Hyperbaric oxygen therapy
What effect does nitric oxide binding to Hb have? (3)
Ends NO reactivity
Opens blood vessels to allow RBC passage
Shifts curve to left
