Respiratory Physiology - Gas transport in the blood Flashcards
What 2 forms does oxygen travel in blood?
in solution in plasma and bond to haemoglobin in red blood cells
Of 200ml, what is the split of Oxygen in plasma and RBC?
3ml PLASMA
297ml RBC
What percent of CO2 is carried in RBC and plasma?
23% RBC
77% PLASMA
very soluble
What is the O2 demand of resting tissue?
250ml/min
How much blood can haemoglobin carry per litre of blood?
197ml
How much O2 is there in each litre of blood?
200ml
197 haemoglobin
3ml plasma
How much oxygen do we deliver to our peripheral tissues per minute?
1000ml per min
What percent of oxygen in peripheries is metabolised?
25%
massive excess
What is the common form of haemoglobin?
A
What does each chain in haemoglobin associate with? and how many oxygens does each heam group associate with?
haem group
1 Fe2+
4 chains and associated with 4 molecules of O2
each 4 chains creates a binding site for 1 oxygen
carry 4 in total per RBC
What is the reaction between the association of the iron atom and haem group called?
oxygenation reaction
weaker reaction than oxidation
What is the cooperative biding of haemoglobin?
as the number of bound oxygen molecules increases in the association reaction, the apparent binding affinity increases
What is the partial pressure of O2 in the alveoli and in arterial circulation?
100mmHg
What does haemoglobin help maintain and how?
maintain partial pressure gradient of O2 in the alveoli and blood
by sucking the oxygen in until saturation
4 O2 per haemoglobin
What does haemoglobin react with oxygen to form?
oxyhaemoglobin
HbO2
How log does it take for the haemoglobin to be fully saturated with Oxygen?
0.25 seconds
Does the fall in oxygen in plasma effect the oxygen bound to haemoglobin?
no, can fall by ~40% and has minimal effect in haemoglobin bound to oxygen
it is still 90% saturated
When do plasma levels effect the oxygen bound to haemoglobin?
when they fall below 60%
What s the normal partial pressure of mercury at resting tissues?
40mmHg
Is veous blood deoxygenated?
no, still has 75% oxygenated, 25% has gone to tissues.
What is venous and arterial partial pressure?
100mmHg is arterial
40mmHg is venous
What happens to the partial pressure of someone who is anaemic?
nothing, PO2 is normal despite total blood O2 content being low
Is it possible for red blood cells to be fully saturated in anaemia? and why?
YES
As saturation relies on partial pressure ad this is normal in anaemia
What happens f you slide the resting cell arterial pressure to a higher partial pressure?
change the offloading of oxygen, not as strong gradient to offload
What factors can cause the oxyhaemoglobin curve to shift?
pH
PCO2
Temp
DPG
What does a decrease in pH, increase in PCO2 and temp…
cause the oxyhaemoglobin curve to shift in what direction?
(exercise)
right
Bohr effect - promoting oxygen offloading at peripherals
What does a decrease in pH, increase in PCO2 and temp…
aid in loading or unloading of oxygen at peripherals?
unloading
reduces affinity of oxygen and haemaglobin.
the oxygen becomes less saturated with oxygen
give oxygen to peripherals
what happens to haemoglobins affinity for oxygen when…
pH increases
pCO2 decreases
Temp decreases?
curve shift left
increase affinity for oxygen
What is occurring is
pH increases
pCO2 decreases
Temp decreases?
hypothermia
peripheral tissues cannot access oxygen as the affinity of haemoglobin has increased
What is DPG?
diphosphoglycerate
When do RBC produce more DPG?
HYPOXIA
chronic lung or heart disease
high altitudes
help maintain oxygen release
What is the Bohr effect?
describes red blood cells’ ability to adapt to changes in the biochemical environment
Does carbon monoxide have a higher affinity for haemoglobin than oxygen?
yes
very high
hard to get off once bound
What diseases does CO occur?
hypoxia and anaemia
What is the partial pressure gradient of CO2 from peripherals to arterial structures?
peripheral = 46 mmHg
arterial = 40 mmHg
