Oxygen and carbon dioxide transport

Question 1

how is oxygen transported

Answer 1

in RBC (erythrocytes)
oxygen binds to haemoglobin to form oxyhaemoglobin

Question 2

how are rbc adapted

Answer 2

biconcave for large SA for more diffusion
no nucleus for more space haemoglobin

Question 3

how is oxygen carried

Answer 3

rbc enter capillaries in lung where oxygen levels low so steep conc between o2 in air and alveoli
oxygen moves into rbc and forms oxyhaemoglobin
as soon as one oxygen binds easier for second
oxygen is bound so free o2 conc stays low in rbc so steep conc until haem saturated

Question 4

how is oxygen then moved out rbc

Answer 4

at tissues conc co2 lower so o2 moves out rbc down conc gradient

Question 5

what is oxygen dissociation curve

Answer 5

% saturation(left) against partial pressure oxygen (bottom axis)
low partial pressure few haem bound to oxygen
high partial pressure lots bound to oxygen so easy to pick up more
haem saturated as all haem bound so levels off
s shape curve

has slow start as hard to bind
then steep increase as it becomes easier
levels off as saturated

Question 6

talk about the affinity for oxygen

Answer 6

with inc partial pressure haemoglobins affinity for oxygen increases
one haem binds o2 changes structure so easier so affinity increases again

Question 7

problem with the affinity

Answer 7

needs high to absorb from air but if too high wont dissociate
why good that affinity varies with partial pressure as absorb at lungs and dissociate at tissues

Question 8

what is affinity

Answer 8

attraction of oxygen

Question 9

what is partial pressure

Answer 9

pressure exerted by gas in kPa

Question 10

what is the bohr effect

Answer 10

more co2 then lower affinity so even more released
graph shifts right

enhances oxygen transport as means more released at tissues as that is where co2 is produced in respiration

Question 11

how is fetal haemoglobin different

Answer 11

has higher affinity to acquire oxygen from mothers blood in the placenta even under low partial pressure

aided by gamma chains instead of beta chains

graph shift left

fetal haem replaced few months after birth so that it dissociated oxygen to its tissues

Question 12

how is co2 transported

Answer 12

dissolved into plasma 5%

bind to haemoglobin to form carbaminohaemoglobin 10%

hydrogen carbonate ions 85%

Question 13

how is co2 transported in carbonate ions

Answer 13

co2 into rbc
co2 converted to carbonic acid by the enzyme carbonic anhydrase
carbonic acid splits to H+ and HCO3 ions
HCO3 diffuse out down conc
replaced by cl- ions to keep neutral (chloride shift)
h+ combine oxyhaemoglobin (H2Co3) form haemoglobinc acid
increases oxygen release