Carriage of gases

Question 1

Where is oxygen found in the body?

Answer 1

in alveolar gas in lungs, in solution in plasma, Majority bound to RBC, Bound to myoglobin in muscle

Question 2

oxygen in solution equation

Answer 2

O2 in sol=pp of O2 x solubility

Question 3

what is pp of O2 in aterial blood?

Answer 3

13.3kPa

Question 4

solubility of O2 in blood

Answer 4

0.225ml O2 per litre of blood kPa

Question 5

How much oxygen per litre of blood

Answer 5

13.3x0.225= 3ml litre

Question 6

Total amount of O2 in arterial blood

Answer 6

200ml

Question 7

what are our oxygen requirements at rest

Answer 7

250ml a minute at rest

Question 8

what are our oxygen requirements during exercise

Answer 8

can increase upwards of 4000ml

Question 9

structure of RBC

Answer 9

Biconcave, flexible, small, large SA to vol ratio, 7um in diameter, no nucleus so more space for Hb, contains 280million Hb molecules, Hb has 4 prosthetic groups (fe)
consists of 2 alpha and 2 beta chains in adults. it is a globular protein, is soluble

Question 10

Haemoglobin+oxygen=

Answer 10

oxyhaemoglobin

Question 11

Haemoglobin-oxygen=

Answer 11

deoxyhaemoglobin

Question 12

equation for association

Answer 12

HHb+O2—-HbO2 + H+

Question 13

What facilitates the affinity of O2

Answer 13

Concentration of CO2, when high affinity decreases, O2 is released

Question 14

Binding of O2 to haem

Answer 14

Affinity is low, as first O2 binds leads to a change in shape, increases the affinity for 2 & 3rd bind easier, 4th takes longer as it attaches to remaining prosthetic group

Question 15

Normal oxygen saturation in blood

Answer 15

98

Question 16

Describe the Bohr effect

Answer 16

When the affinity for O2 is facilitated by the conc of CO2, is a sigmoid (s-shape)

Question 17

PvO2

Answer 17

venous partial pressure of O2= 5.3kPa (40mmHg)

Question 18

PaO2

Answer 18

arterial partial pressure of O2= 13.3kpa (100mmHg)

Question 19

Factors that affect the bohr curve to right (o2 dissociation curve)

Answer 19

dependent on partial p of O2,
increase in temp
increases PCO2
decreased pH (due to CO2)
increased 2,3 DPG (metabolic product in RBC)

Question 20

If curve shifts to right:

Answer 20

Hb affinity for O2 is reduced, O2 is given off to tissues where CO2 is high, Hb is less saturated

Question 21

If curve shifts to left:

Answer 21

Hb affinity for O2 is increased, O2 is picked up at lungs

Question 22

effect of CO2 on curve

Answer 22

increased CO2 causes more H+ concentration, reducing pH
a drop in pH shifts curve to the right, pH causes bond to weaken between Hb and O2, leading to offloading

Question 23

CO2 transport in blood:

Answer 23

10% dissolved in plasma
15% if CO2 bound to plasma proteins
75% transported as carbonic acid

Question 24

Buffering of CO2 equation

Answer 24

H2O+CO2-H2CO3-H++HCO3-

Question 25

explain equation

Answer 25

CO2 diffuses into RBC water combines with co2 to form carbonic acid, this is catalyzes by carbonic anhydrase enzyme, this causes carbonic acid to dissociate into H+ and HCO3- ions, HCO3- diffuses out of RBC, Cl- moves in to restore electrochemical balance H+ lowers pH

Question 26

Carbamino compounds

Answer 26

CO2 combines with Hb to form carbinohaemoglobin H+ and CO2 can inhibit binding of O2,(Haldane effect)

Question 27

Define Haldane effect:

Answer 27

Binding of O2 to Hb promotes release of CO2 and H+, e.g., at lungs

Question 28

At tissues:

Answer 28

15% of CO2 replaces O2 in RBC forming carboxyhemoglobin, causes O2 to be released at tissues, causes an increase in H+, so lowers pH, leading to more O2 to be released

Question 29

At Lungs:

Answer 29

High affinity for O2, as O2 combines with Hb to form oxyhaemoglobin, releases CO2 at lungs, allowing it to be breathed out, bicarbonate recombine with H+ to form carbonic acid which dissociates to water & CO2 which diffuses out of RBC

Question 30

What are the percentage regarding CO2: amount of CO2 dissolved in plasma Amount of CO2 bound to Hb Amount of CO2 transported as HCO3- ions

Answer 30

7% dissolved in plasma 70% carried as HCO3- ions 23% is attached to Hb to form carbinohaemoglobin