Haemoglobin and Gas Transport Flashcards
What is the main carrier for oxygen in the blood?
Haemoglobin
How is most of CO2 transported in the blood?
In solution in plasma
Do gases travel in gaseous phase when in plasma and why?
No as bubbles in the blood would cause an air embolism
How much arterial O2 is extracted by peripheral tissues at rest?
25%
What is the main determinant of the degree to which haemoglobin is saturated with oxygen?
Partial pressure of oxygen in arterial blood
What are the 4 forms of haemoglobin in red blood cells?
HbA
HbA2
HbF
glycoisated Hb
What is the most common form of haemoglobin?
HbA (makes up 92%)
What is HbF?
Foetal haemoglobin
What is the reserve capacity of haemoglobin for oxygen and normal venous PO2?
75%
Does HbF have a higher or lower affinity than HbA and why?
Higher affinity to allow O2 extraction from maternal blood
What is the definition of anaemia in relation to O2 carrying capacity of the blood?
Any condition where O2 carrying capacity of the blood is compromised
During anaemia what happens to PaO2 and total blood O2?
PaO2 is normal
Total blood O2 is low
Are red blood cells able to be fully saturated with O2 in anaemia and why?
Yes as PaO2 is normal
What effect does acidosis and alkolisis have on haemoglobin’s affinity for O2?
Acidosis - decreases affinity
Alkalosis - increases affinity
What effect does increasing the PCO2 have on haemoglobin’s affinity for O2?
As PCO2 increases, affinity decreases
What effect does increasing the temperature have on haemoglobin’s affinity for O2?
As temperature increases, affinity decreases
What effect does adding 2,3-DPG have on haemoglobin’s affinity for O2?
As 2,3-DPG is added, affinity decreases
What effect does carbon monoxide have on haemoglobin?
It binds to haemoglobin with 250 times greater affinity than O2 causing it to competitively inhibit O2
What are 6 symptoms of carbon monoxide poisoning?
Hypoxia Anaemia Nausea Headaches Cherry red skin Mucous membranes
What are 2 of the possible consequences of carbon monoxide poisoning?
Brain damage
Death
What are the 3 outcomes when CO2 diffuses from the tissues into the blood?
70% combines with water in the erythrocytes to form carbonic acid
23% combines in the erythrocytes with deoxyhemoglobin to form carbamino compounds
7% remains dissolved in plasma and erythrocytes
What effect does hypoventilation have on respiratory pH and why?
Hypoventilation causes CO2 retention leading to respiratory acidosis
What effect does hyperventilation have on respiratory pH and why?
Hyperventilation blows off more CO2 leading to respiratory alkalosis
