PHYSIOLOGY: Carriag Of Bloog Gases Flashcards
Hawk goo in consist of ?
A pair of α-like chains and a pair of β-like chains
Haemoglobin can bind to how many O2 molecules?
4
When oxygen is bound to haemoglobin it is called?
oxyhaemoglobin
If 2 molecules of oxygen are bound to one Hb molecule, it is?
50% saturated
When blood PCO2 is high, the affinity of Hb for oxygen falls, the curve shifts?
To the right and more oxygen is released
When pH is reduced (high concentration of hydrogen ion), the affinity of Hb for oxygen ?
Reduces
More O2 released (lower SaO2)
Curve shifts to the right
Increasing temperature ?
Reduces Sa02- affinity to 02
Curve shifts to the right
Decreasing temperature?
Curve shift to the left
Higher Sa02
Effect of 2,3 DPG on affinity of haemoglobin
Curve shift to the right
Promotes release of O2
Foetal Hb affinity for oxygen
Higher affinity for O2 than maternal HbA
Myoglobin has a …… to O2 than haemoglobin
GREATER affinity
Accepts O2 from haemoglobin when PO2 in blood is low and release O2 in muscle
The myoglobin binding curve lacks the sigmoidal shape of the haemoglobin binding curve
Why?
Because of the single O2 binding site in each molecule
CO2 transport in blood
A small amount of CO2 dissolves in plasma
●Most carbon dioxide diffuses into red blood cells
●Some carbon dioxide attaches to Hb, displacing oxygen (note O2 affinity)
●Most carbon dioxide reacts with water catalysed by carbonic anhydrase to produce bicarbonate and hydrogen ion
●Bicarbonate diffuses out of the red blood cell and is replaced by chloride ions (chloride shift)
●In the lungs the process is reversed
Why must hydrogen ion concentration be kept constant?
Changes in pH affect:
●The affinity of Hb for oxygen
●The rate of enzyme reactions (optimal within a very narrow range)
●The ionisation states of many substances, disrupting their structure e.g. DNA
Metabolic processes affect …………, and respiratory processes affect ……
Bicarbonate concentration
PCO2
