Haemoglobin and Gas transport Flashcards
How much oxygen dissolved per litre of plasma
3ml
Haemoglobin is RBCs increases oxygen carrying capacity to
200ml/L
Bulk of CO2 is transported in solution in
plasma
Arterial oxygen content is 3ml/L and cardiac output is 5 litres therefore oxygen delivery to tissues is…
15ml/min
Oxygen demand of resting tissues
250ml/min
Only ……% of arterial oxygen is extracted by peripheral tissues at rest
25
each litre of systemic arterial blood contains ~……ml of oxygen
200
more than …..% of oxygen is bound to haemoglobin (the rest is dissolved in plasma)
98
Haemoglobin cooperatively binds
4 molecules of oxygen
how many ml of oxygen bind to each gram of haemoglobin?
1.34 ml
92% of haemoglobin in RBCs is in the form
HbA
8% (rest of) haemoglobin in RBCs is made up of
HbA2, HbF and glycosylated Hb
Major determinant of the degree of which haemoglobin is saturated with oxygen is the
partial pressure of oxygen in arterial blood
What is the partial pressure of a gas?
The hypothetical pressure of the gas if it alone occupied the entire volume of the original mixture at the same temperature
Haemoglobin is almost 100% saturated at the normal systemic arterial PO2 which is…
100mmHg
At normal venous PO2 - there is still….. %reserve capacity of saturated haemoglobin
75%
HbF
Foetal Haemoglobin
Anaemia
Any condition where the oxygen capacity of the blood is compromised
(eg iron deficiency, haemorrhage, Vitamin B12 deficiency)
Oxygen content of plasma is
3mL O2/L blood
Oxygen content of RBC
197ml O2/L blood
In anaemia, PaO2 is normal despite total blood oxygen content being
low
Affinity of haemoglobin for oxygen changes in response to certain
chemical factors
Affinity of haemoglobin for oxygen is decreased by a
decrease in pH
increase in PCO2
Increase in temperature
binding of 2,3 disphosphoglycerate
2,3-DPG is synthesised by …… and increases in situations where there is …….
erythrocytes
inadequate oxygen supply
Carbon monoxide binds to Hb to form
carboxyhemoglobin
carboxyhaemoblogin has an affinity …… greater than oxygen
250
Symptoms of Carbon Monoxide poisoning
nausea hypoxia anaemia headaches cherry read skin mucous membranes
potential brain damage and death
Hypoxaemic hypoxia
most common hypoxia
reduction in oxygen diffusion at lungs either due to decreases PO2atmos or tissue pathology
Anaemic Hypoxia
Reduction in O2 carrying capacity of blood due to anaemia (RBC loss/ iron deficiency)
Stagnant Hypoxia
Heart disease results in inefficient pumping of blood to lungs/ around the body
Histotoxic Hypoxia
poisoning prevents cells utilising oxygen delivered to them (eg carbon monoxide/cyanide)
Metabolic Hypoxia
oxygen delivery to the tissues does not meet increased oxygen demand by cells
