phy 4

Question 1

“Effect of Partial

Pressure on Gas Solubility?”

Answer 1

increasing partial pressure in gas phase, proportionally increases the concentration of the gas in the liquid phase

Question 2

partial pressure of a gas in solution

Answer 2

partial pressure in the gas mixture with which it is in equilibrium

Question 3

henrys law

Answer 3

At a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid (e.g. blood) is directly proportional to the partial pressure of that gas in equilibrium with that liquid

Question 4

resting O2 consumption of body cells

Answer 4

250ml/min

Question 5

in which forms is oxygen found in the blood and what percentage of O2 do these forms carry, respectively

Answer 5

“oxygen bound to haemoglobin - 98.5%

oxygen carried in its dissolved form - 1.5%”

Question 6

normal arterial O2 concentration

Answer 6

200ml per litre

Question 7

normal arterial PO2

Answer 7

13.3kPa

Question 8

normal haemoglobin(Hb) concentration

Answer 8

150 grams per litre

Question 9

“how many oxygen molecules can one haemoglobin molecule bind to?
what structures on the haemoglobin molecule allow oxygen binding?”

Answer 9

“1 Hb can bind to 4 oxygen molecules

oxygen binding is facilitated by the 4 haem groups present in a haemoglobin molecule. each haem group can reversibly bind to oxygen”

Question 10

when is haemoglobin considered to be fully saturated

Answer 10

When all the Hb present is carrying its maximum O2 load

Question 11

which factor primarily determines the percent saturation of haemoglobin with O2

Answer 11

PO2

Question 12

normal PO2

Answer 12

95% or above

Question 13

what is the composition of haemoglobin

Answer 13

“2 Beta Chains
2 Alpha Chains
4 Haem Groups”

Question 14

what shape is an oxygen haemoglobin saturation curve

Answer 14

sigmoid

Question 15

what is oxygen delivery to tissues a function of

Answer 15

“oxygen content of arterial blood

cardiac output”

Question 16

oxygen delivery index equation

Answer 16

“DO2I = CaO2 x CI

where
DO2I = Oxygen Delivery Index (ml/min/metre2)

CaO2 = Oxygen content of arterial blood (ml/L)

CI = Cardiac index (L/min/metre2)
“

Question 17

cardiac index

Answer 17

cardiac output with regard to the body surface area(i.e. size of the individual)

Question 18

O2 content of arterial blood is determined by

Answer 18

“haemoglobin concentration[Hb] (gram/L)

saturation of Hb with O2, SaO2”

Question 19

CaO2 equation

Answer 19

“CaO2 = 1.34 x [Hb] x SaO2

“

Question 20

what is the SaO2 determined by

Answer 20

PO2

Question 21

“Oxygen Delivery to the Tissues can be impaired by

“

Answer 21

“respiratory disease
decreased partial pressure of inspired oxygen - they can decrease arterial PO2 and hence decrease Hb saturation with O2 and O2 content of the blood
heart failure - decreases cardiac output
anaemia - this decreases Hb concentration and hence decreases O2 content of the blood
asthma”

Question 22

Partial pressure of inspired oxygen depends on

Answer 22

“total pressure (e.g. atmospheric pressure)

proportion of oxygen in gas mixture (about 21% in atmosphere)”

Question 23

what happens to the partial pressure of inspired oxygen when the altitude increases

Answer 23

decreases because increasing altitude decreases atmospheric pressure thus decreasing the pressure gradient between the atmosphere and the intraalveolar pressure

Question 24

water vapour pressure in the lungs

Answer 24

47mmHg

Question 25

how do respiratory disease and a decreased partial pressure of inspired oxygen affect oxygen delivery to the tissues

Answer 25

they can decrease arterial PO2 and hence decrease Hb saturation with O2 and O2 content of the blood

Question 26

cooperativity

Answer 26

binding and unbinding of one oxygen to haemoglobin increases and decreases the affinity of Hb for O2, respectively

Question 27

components of foetal haemoglobin

Answer 27

2 alpha and 2 gamma subunits, whilst HbA has 2 alpha and 2 beta subunits

Question 28

why does HbF have a higher affinity for O2 than HbA

Answer 28

HbF interacts less with 2,3- Biphosphoglycerate in red blood cells than HbA

Question 29

whats the structural significance of HbF

Answer 29

it allows O2 to transfer from mother to foetus even if the PO2 is low

Question 30

presence of myoglobin in the blood indicates

Answer 30

muscle damage