20. blood gas transport

Question 1

gas transport

Answer 1

process of carrying O2 from the alveoli to systemic tissues and CO2 from the systemic tissues to the alveoli
via blood transport

Question 2

gas exchange via diffusion is dependent upon (5)

Answer 2

diffusion surface area eg large, moist
diffusion distance eg short
concentration gradient between alveolar air and blood 
solubility of gases 
coordinated blood flow and airflow

Question 3

what is daltons law of partial pressure

Answer 3

the total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture

Question 4

what is partial pressure

Answer 4

the pressure exerted by each gas

is directly proportional to its percentage in the total gas mixture

Question 5

henrys law (solubility)

Answer 5

amount of gas that dissolves in water is determined by its solubility in water and its partial pressure in air
at equilibrium the amount of dissolved gas in solution is proportional to the partial pressure of that gas

Question 6

which gas is more soluble (able to dissolve in solution)

Answer 6

carbon dioxide

Question 7

strcture of haemoglobin

Answer 7

4 globular protein subunits (2a and 2B)

each subunit has a globin protein and a non protein haem (iron) group

Question 8

function of haemoglobin

Answer 8

each Hb molecule binds four molecules of oxygen to it in a rapid and reversible reaction
Hb + O2 to HbO2
deoxyhaemoglobin to oxyhaemoglobin

Question 9

Hb saturatio

Answer 9

the percentage of haem units in a Hb molecule that contain bound oxygen

Question 10

the oxygen binding to Hb is affected by (4)

Answer 10

PO2 of blood
blood pH
temperature
state of O2 binding to the Hb molecule

Question 11

100% PO2 means the Hb saturation is

Answer 11

100%, the higher the p)2 the more O2 combines with Hb

Question 12

explain the bohr shift

Answer 12

decreased pH or increased CO2
curve shifts to the right
better unloading of oxygen at the tissues

Question 13

what happens to the dissociation curve if theres an increase in temperature

Answer 13

curve flattensshifts tp right

high O2 unloading in active tissues

Question 14

what happens to the dissociation curve if theres an increase in DPG

Answer 14

curve shifts to right so more )2 unloading in tissues due to anaerobic conditions

Question 15

what symptoms would u experience at high altitudes

Answer 15

foogy brain weak muscles
hypoxia- blood O2 conc very low
faster deeper breathing

Question 16

carboxyhaemoglobin

Answer 16

CO2 binds tighter than O2

dramticallt reduces the ability of O2 to bind to Hb

Question 17

methaemoglobin

Answer 17

the Fe2+ in haem is oxidised to Fe3+ by eg a drug
this means it is unable to carry O2
overtime the Fe2+ is slowly converted back

Question 18

fetal haemoglobin

Answer 18

2a and 2Y

curve is shifted to left, has a higher affinity for o2 which is important in transferring O2 across the placenta

Question 19

carbon dioxide

Answer 19

is generated by aerobic metabolism in peripheral tissues

co2 molecules ente the bloodstream then get transported

Question 20

what are the three ways in which CO2 can be transported

Answer 20

1. 70% is converted to carbonic acid formation H2CO3- and transported in plasma as bicarbonate ion HCO3-
2. bound to haemoglobin as carbaminohaemoglobin (23%)
3. remains dissolved in plasma (7%)

Question 21

1. describe the chloride shift

Answer 21

CO2 + H2O
to carbonic anhydrase H2CO3
dissociated into H+ and HCO3- (carbonic acid)
the HCO3- moves out of the RBC in exchange for Cl-

Question 22

how is carbaminohaemoglobin formed

Answer 22

the CO2 binds with HbNH2 to form HbNHCOOH

COO= carbamino

Question 23

what are the best buffers in red cells (2) to consume/release H+

Answer 23

histidine residues in haemoglobin: HbNNH + H+ to HbNNH2+

deoxygenated haemoglobin has the strongest affinity for H+

Question 24

describe the Haldane effect in the lungs (5)

Answer 24

oxygenation of Hb 
lowers the affinity for H+ ions 
decreases buffering power 
release of H+
aids in unloading of CO2 in the lungs

Question 25

describe the Haldane effect in the tissues

Answer 25

deoxygenation of Hb
higher affinity for H+ ions 
increase in buffering power 
increase in H+ uptake 
aids intaking CO2 from tissues