Transporting Oxygen Flashcards
Adaptions of erythrocytes
Biconcave- increases SA available for diffusion, also helps flexibility
Continuously formed in bone marrow
haemoglobin
No membrane bound organelles
Haemoglobin
Globular protein
Pigment carries o2
4 polypeptide chains, 2 alpha, 2 beta
Haem group at the centre, contains fe2+ which has an affinity for oxygen
No nucleus or organelles to allow more space of 02
How do erythrocytes carry oxygen
When erythrocytes enter the lungs o2 levels are low
Creates a steep concentration gradient with the alveoli which have high o2 concentration.
O2 moves into erythrocytes and binds to the haemoglobin
Once 1 molecule binds to the haem group the tertiary structure of the molecule changes shape making it easier for more o2 to bind. Positive cooperation
As o2 is bound to the haemoglobin the o2 conc in the erythrocytes stays low until all of the haemoglobin is saturated
Why does foetal haemoglobin need a higher affinity for o2
A foetus is dependant on its mother for its oxygen needs
Maternal blood runs close to the fetal blood in the placenta
Planeta has a low partial pressure of oxygen
At all partial pressures fetal haemoglobin has a higher affinity for o2 as allowing the featus to remove o2 from the maternal blood as they move past each other
Explain the partial pressure of oxygen vs saturation curve
At low pao2, few haem groups are bound to o2 so o2 saturation is low.
At higher pao2 more haem groups are bound to o2 making it easier for more o2 to be picked up
The haemoglobin becomes saturated at very high pao2 as all haem groups are bound
3 ways co2 is transported from tissues to lungs
5% is dissolved in the plasma
10-20% is combined with amino groups to form a carbaminohaemoglobin
75-85% is converted to hydrogen carbonate ions in the cytoplasm of the red blood cells
Process of transporting carbon dioxide
Co2 diffuses from tissue into blood stream
5% remains in plasma , 95% diffuses into RBC’s
10-20% binds to haemoglobin creating carbaminohaemoglobin
75-85% converted into carbonic acid ( H2CO3), catalysed by carbonic anhydrase
Carbonic acid dissociates into h+ and hco3-
H+ is removed by buffers, haemoglobin
Hco3- moves out of the RBC’s in exchange for cl-, chloride shift due to conc gradients
Oxyhemoglobin dissociates under h+ influence hbo8 —> hb + 4o2
O2 is released into surrounding cells
Why does the RBC’s go through the processes of converting co2
By removing co2 and converting it to hco3- , the erythrocytes maintain a steep concentration gradient for co2 to diffuse from the respiring tissues into the erythrocytes
Effect of carbon dioxide on oxygen association curve
Bohr effect - as partial pressure of co2 rises haemoglobin gives up oxygen more readily.
Result of the Bohr effect
In active tissues with a high partial pressure of carbon dioxide haemoglobin gives up oxygen more readily.
In the lungs where the proportion of carbon dioxide is low oxygen binds to the haemoglobin more easily
How do the components of tobacco smoke effect cardiovascular system
Nicotine- increases stickiness of platelets, Formation of blood clots ,Causes release of adrenaline, Constriction of arterioles, Reduced blood flow, therefore oxygen supply
Carbon monoxide
Combines permanently with haemoglobin to from carboxyhemoglobin
Reduced oxygen capacity of blood
Increased heart rate / blood pressure
Damage to lining endothelium
Increased risk of coronary heart disease
Why cartilage is essential in the trachea
Provide strength to stop the cartilage collapsing due to the changes in pressure after inhalation and exhalation
