L16 - respiratory physiology - transport and exchange of gasses

Question 1

what is daltons law

Answer 1

the individual pressure of a gas in a mixture is its partial pressure

sum of partial pressures = total pressure

Question 2

what is henrys law

Answer 2

gasses diffuse from high partial pressure to low partial pressure

Question 3

how much o2 is consumed by tissues per min

Answer 3

250ml

Question 4

how much CO2 is produced by tissues per min

Answer 4

200ml

Question 5

what is the respiratory quotient

Answer 5

o2 consumed

Question 6

CO at rest

Answer 6

5L/min

Question 7

Va at rest
total air
oxygen only

Answer 7

4.2L/min

882

Question 8

what is PO2 at the alveoli

Answer 8

13.3

Question 9

what is PO2 in tissues

Answer 9

5.3

Question 10

what factors affect rate of diffusion

Answer 10

Partial pressure difference
diffusion barrier thickness & permeability
solubility of gas in water

Question 11

what is PCO2 in tissues

Answer 11

6.1

Question 12

what is PCO2 in alveoli

Answer 12

5.3

Question 13

what is systemic PO2

Answer 13

12.5

Question 14

what is systemic CO2

Answer 14

5.3

Question 15

why doesnt systemic PO2 = Alveolar PO2

Answer 15

1. anatomical right to left shunt

2. partial draining of coronary venous blood into LV

Question 16

explain anatomical right to left shunt

Answer 16

deoxygenated bronchial vein blood mixes with oxygenated pulmonary vein blood

Question 17

define % saturation

Answer 17

%of O2 binding sites on Hb , bound to O2

Question 18

define O2 content

Answer 18

sum of gas present in blood (bound to HB and dissolved in plasma)

Question 19

define max O2 carrying capacity

Answer 19

amount of O2 blood is capable of carrying when Hb is 100% saturated

Question 20

why do we need haemoglobin

Answer 20

for dissolved oxygen alone CO would have to be 83L/min to supply tissues with sufficient O2

Question 21

what factors affect binding of O2 to Hb

Answer 21

PO2 & co - operativity
PCO2 (pH)
temperature
2, 3 diphosphoglycerate

Question 22

what is the normal shape of the o2 Hb dissociation curve

Answer 22

sigmoidal

Question 23

explain cooperativity of Hb

Answer 23

binding of each successive O2 increases affinity of remaining binding sites

release of O2 causes release of O2 from the other binding sites

Question 24

what is 2,3 diphosphoglycerate

Answer 24

product of glycolysis that accumulates when o2 supply isn’t sufficient

Question 25

``` what effect does increased PCO2 temp [2,3 DPG] and decreased pH have on the O2 Hb dissociation curve ```

Answer 25

causes a right shift - decreased affinity of oxygen so oxygen dissociates

Question 26

define oxygenation

Answer 26

the binding of oxygen to Hb binding sites

Question 27

``` what effect does decreased PCO2 [2,3 DPG] temp and increased pH have on the O2 Hb dissociation curve ```

Answer 27

shift to right, higher affinity for oxygen so it wont dissociate in tissues

Question 28

explain the effects of anaemia on oxygen transport

Answer 28

1. reduced no. of rbc reduced Hb 2. reduced O2 carrying capacity 3. mild tissue hypoxia

Question 29

effects of anaemia on O2 Hb dissociation curve

Answer 29

flatter version of normal - not as high

Question 30

explain the effects of CO poisoning on oxygen transport

Answer 30

1. CO binds to Hb at higher affinity than O2 2. fewer O2 binding sites available disrupts cooperativity (O2 that binds doesn't dissociate) 3. severe hypoxia

Question 31

effects of CO poisoning on O2 Hb dissociation curve

Answer 31

no longer sigmoidal | lower and flatter

Question 32

how is CO2 transported in blood

Answer 32

HCO3 carbamino compounds (on Hb) dissolved in plasma

Question 33

what enzyme speeds up the CO2 - HCO3 reaction

Answer 33

carbonic anhydrase

Question 34

what is the haldane effect

Answer 34

deoxy Hb promotes the uptake of CO2 by RBCs better than oxygenated Hb due to haldane effect A haldane effect B

Question 35

what mechanisms favour the forward reaction of CO2 - HCO3

Answer 35

H+ binds to deoxy Hb (removing H+) | HCO3 leaves via chloride shift

Question 36

what is the haldane effect A

Answer 36

H+ binds to deoxy Hb (removing H+) | favouring the forward reaction of CO2 - HCO3

Question 37

what is the haldane effect B

Answer 37

deoxy Hb more readily forms carbamino compounds with CO2 than oxy Hb does

Question 38

what is hypocapnia

Answer 38

drop in PaCO2 increased pH respiratory alkalosis

Question 39

what is hypercapnia

Answer 39

increase in PaCO2 decrease in pH respiratory acidosis