D: abnormal bluish discolouration of skin & mucous membranes

• due to high levels of deoxygenated Hb

Dalton's Law
D: total pressure exerted by mixture of inert gas
=
sum of partial pressures of individual gases in a volume of air

Henry's Law
D: the no. of molecules dissolving in liquid directly proportional to the partial pressure of the gas

D: partial pressure gas would need in gaseous phase to equilibrate with that solution

concentration of gas in solution is NOT THE SAME as its partial pressure

• solubility of gas affects its concentration

matching ventilation to perfusion

concentration of O2 in
inspired air (FiO2)

1. inspired air - 159 mmHg
2. alveolar air - 104 mmHg - 13.8kPa
3. oxygenated blood - 95 mmHg - 12.7kPa
4. tissue fluid (in respiring tissue) - 40 mmHg - 5.4kPa
5. deoxygenated blood - 40 mmHg

• 4 peptide chains
  (2 alpha & 2 beta)

• each chain haem group

• each containing iron atom
  (where O2 binds)

means that fetal Hb can bind to oxygen MORE TIGHTLY than adult Hb

• so HIGH AFFINITY Hb

D: amount of O2 bound to Hb relative to maximal amount of O2 that can bind to Hb

oxygen capacity =
amount of O2 bound to Hb
AND
amount of O2 dissolved in plasma

X 100

measured using probe (pulse oximeter) applied to finger/earlobe

total oxygen content in blood = 204 mL/L
3 mL/L (plasma) + 201 mL/L (Hb)

illustrates relationship between PO2 in blood & no. of O2 molecules bound to Hb

Plateau (>60mmHg)

• increase in PO2 over wide range 60-100
• minimal effect on Hb saturation (90-100%)

Steep increase (<60mmHg)

• large amount O2 binds with Hb
• even though only small increase in PO2
• facilitates release&diffusion of O2 into tissues

Hb has specific affinity for O2

• as PO2 increases - Hb saturation increases

D: the point on curve where 50% of Hb saturated with O2

when ODC shifts to RIGHT

• increases O2 dissociation
• P50 INCREASES
  why?

1. increased CO2 - increases H+ ions & decreases pH

• aids release of O2 from Hb - Bohr effect
  

2. increased body temp - allows more O2 released into tissue

   
   

3. increased 2,3-DPG (formed in RBC during glycolysis)

• hypoxia, decreased Hb & increased pH = increases 2,3-DPG

when ODC shifts to LEFT

• O2 dissociation inhibited
• P50 DECREASES
  why?

1. exhaled CO2 (decreased) = increases pH
2. decreased body temp - higher Hb affinity (O2 not lost from Hb)

• means in cold temps why extremities blue
• O2 not reaching peripheries

3. decreased 2,3-DPG

benefits

• can extract more O2 from mother
• fetal blood less O2 because shares with mother

differences between V and A are the SAME

• both 50mL/L difference
• 50mL/L of oxygen used by tissues in both

at V and A - anaemic MUCH LOWER

• about half the value of normal

anaemic

• despite less Hb
• as long as Hb normal
• then 98% Hb should still have O2 bound

oxygen consumption (mL/min) =
arterio-venous O2 content difference
x
cardiac output

D: volume of blood pumped out by heart each minute