module 3 - 8.4 transport of oxygen and carbon dioxide in the blood Flashcards
what does affinity mean?
tendency to bind to oxygen
what is the affinity of haemoglobin for oxygen?
high
at high partial pressures of oxygen, what happens to the haemoglobin?
it will bind to the oxygen forming oxyhaemoglobin
what happens to oxygen at high/ low concentration?
high conc. - oxygen binds to haemoglobin
low conc. - oxygen dissociates to haemoglobin
what is the equation for oxyhaemoglobin?
——————————affinity————————————->
Hb + 4O2 ⇌ Hb(O2)4
haemoglobin + oxygen ⇌ oxyhaemoglobin
<—————————dissociation———————————
what is partial pressure?
measuring concentration of gas when mixed with another gas
what is haemoglobins oxygen dissociation curve?
it is a sigmoid curve and plateau’s when all haemoglobin is oxyghaemoglobin
at respiring tissue or capillary beds, what is pO2?
low, so haemoglobin dissociates its oxygen to 20-25% saturation
what happens as oxygen binds to one monomer of Hb?
molecules shift from tense to relaxed state
what does the shift from tense to relaxed state promote?
promotes the binding of oxygen to remaining 3 monomer’s haem group thus saturating the Hb molecule with oxygen
what is cooperative binding?
the first oxygen molecule binds and changes structure of haemoglobin molecule, makes it easier for each successive oxygen molecule to bind
what happens when oxygen starts binding to the haemoglobin?
the alpha bonds start breaking
when does the dissociation from oxyghaemoglobin to haemoglobin occur?
doesn’t happen until capillaries
where is the highest concentration of oxygen?
lungs
where is oxygen concentration low?
in capillaries - its used for respiration
what is deoxygenated haemoglobin?
haemoglobin without the bound oxygen
how is the difference of absorption between oxy & deoxyhaemoglobin?
oxy - lower
deoxy - higher
measured with pulse oximeter
what is the Bohr effect?
- helps oxyhaemoglobin to dissociate and get oxygen more easily
- it describes how high pCO2 affects Hb’s affinity for oxygen
what does CO2 in the plasma form?
carbonic acid, this lowers pH of blood, causes oxyHb to dissociate its oxygen
what happens in respiring tissue? (to do with Bohr effect)
where pCO2 is high, Hb releases O2 more easily
what happens in the lungs? to do with Bohr effect)
- decrease in CO2 causes increase in blood pH (Hb releases O2 more easily)
- where pCO2 is low, Hb binds to oxygen more easily
where is CO2 the highest and what does this cause?
- highest in cells/respiring tissue
- diffuses down conc. gradient to lungs then to air
what molecules trigger the Bohr effect?
- carbon dioxide
- lactic acid
why does lactic acid trigger the Bohr effect?
- lactic acid is produced when cells don’t have enough oxygen
- this increases acidity of blood more than CO2
- cells need more oxygen