CH8 transport of oxygen and carbon dioxide in the blood Flashcards
1
Q
Where are erythrocytes formed
A
Bone marrow
2
Q
Why do eythrocytes only last for 120 days
A
Have no nucleus
3
Q
Structure of haemoglobin
A
- four polypeptide chains
- each with an iron containing prosthetic haem group
4
Q
What is positive cooperativity
A
- as soon as one molecule binds to a haem group the molecule changes shape
- makes it easier for next oxygen to bind
5
Q
How is a steep concentration gradient maintained in erythrocytes
A
- oxygen bound to haemoglobin
- free oxygen concentration stays low
6
Q
Why is oxygen disssociation curve an s shape
A
- once first oxygen molecule attached, haemoglobin changes shape so other oxygen molecules are added rapidly
- curve levels out as once all haem groups are bound to oxygen, haemoglobin is saturated and cannot take up anymore
7
Q
What is the bohr effect
A
- as partial pressure of carbon dioxide rises, haemoglobin gives up oxygen more easily
8
Q
Why is the bohr effect important in the body
A
- in active tissues with high ppco2, haemoglobin gives up oxygen more easily
- in lungs with a low amount of co2, oxygen binds to haemoglobin more easily
9
Q
Fetal haemoglobin
A
- fetus completely dependant on mother to supply with oxygen
- has a higher affinity for oxygen than mother
- if blood had the same affinity, little to no oxygen would be transferred to blood of foetus
10
Q
What are the three main ways carbon dioxide is carried in the blood
A
- 5% in plasma
- 10-20% combined with amino groups in polypeptide chains of haemoglobin
- 75-85% converted to hydrogen carbonate ions in red blood cells
11
Q
How are hydrogencarbonate ions formed
A
- carbon dioxide reacts with water, catalysed by carbonic anydrase, to form carbonic acid
- carbonic acid dissociates to form hydrogen ions and hydrogen carbonate ions
12
Q
What is chloride shift
A
- hydrogen carbonate ions move out of red blood cells into blood plasma
- chloride ions move in to maintain electrical balance of cell
