RESP- Oxygen Transport

Question 1

how is oxygen transported around the body

Answer 1

bound to haemoglobin and dissolved in plasma

Question 2

how is carbon dioxide transported in the body

Answer 2

as bicarbonate, bound to haemoglobin, dissolved in plasma

Question 3

is more oxygen bound to haemoglobin or dissolved in the plasma

Answer 3

bound to haemoglobin - oxygen has low solubility in plasma

Question 4

what is the partial pressure of oxygen a measure of

PaO2

Answer 4

how much oxygen is in the plasma

Question 5

what is total oxygen content (CaO2) a measure of

Answer 5

volume of oxygen carried in each litre of blood- includes oxygen bound to haemoglobin and dissolved in plasma

Question 6

what is oxygen saturation a measure of (SaO2)

Answer 6

proportion of haemoglobin binding site which currently have oxygen bound to them

Question 7

what is the oxygen-haemoglobin dissociation curve

Answer 7

proportion of saturated haemoglobin plotted against the partial pressure of oxygen

Question 8

what shape is the oxyhaemoglobin dissociation curve

Answer 8

sigmoidal

Question 9

explain the oxyhaemoglobin dissociation curve

Answer 9

as the partial pressure of oxygen increases the saturation of haemoglobin increases - until a certain point when haemoglobin saturation is full

therefore at high pO2 - there is high affinity for oxygen - O2 binding

at low pO2 - there is low affinity for O2 - O2 release

Question 10

how is oxygen released from haemoglobin to respiring tissues

Answer 10

at tissues there is a low ppO2 so there is oxygen release (oxygen-haemoglobin dissociation curve)
this subsequently causes more release and therefore there is rapid oxygen unloading at low partial pressures

Question 11

what is P50 in relation to the oxygen dissociation curve

Answer 11

partial pressure of oxygen in blood when haemoglobin is 50% saturated

Question 12

why is P50 an important measure

Answer 12

some physiological disease processes may shift the dissociation curve to the left or the right changing the P50 value
therefore this value is comparative

Question 13

what are the effects of shifting the oxyhaemoglobin curve to the right

Answer 13

right shift - lower oxygen affinity - so P50 occurs at a higher PO2 - increased oxygen unloading

Question 14

what are the effects of shifting the oxyhaemoglobin curve to the left

Answer 14

left shift - higher oxygen affinity - P50 occurs at a lower ppO2 - impaired oxygen unloading

Question 15

what factors can shift the oxyhaemoglobin dissociation curve to the left / the tight

Answer 15

left - decreased pCO2, decreased temperature, decreased 2,3-DPG, increased pH, HbF

right - increased pCO2, increased temperature, increased 2,3-DPG, decreased pH

Question 16

what is the bohr effect

Answer 16

the effect of pH, CO2 and temperature on oxygen affinity

Question 17

how is HbO2 affinity different in:

the lungs
resting tissue
working tissue

Answer 17

lungs - increased pO2, decreased pCO2, increased pH = increase in O2 saturation

resting tissue - decreased pO2 - oxygen moves from haemoglobin to tissues

working tissues - decreased pO2, increased pCO2, 2,3-DPG and lactic acid = decrease pH = lower HbO2 affinity = more oxygen moves from haemoglobin to respiring tissues

Question 18

what colours do oxyhaemoglobin and deoxyhaemoglobin appear

Answer 18

oxyhaemoglobin - red

deoxyhaemoglobin - blue

Question 19

what produces the colour of cyanosis

Answer 19

purple discoloration of the skin due to build up of deoxyhaemoglobin

Question 20

what is the difference between central cyanosis and peripheral cyanosis

Answer 20

central cyanosis - bluish discolouration of core, mucous membranes and extremities due to inadequate oxygenation of blood - due to hypoventilation, V/Q mismatch

peripheral cyanosis - bluish colouration confined to extremities (fingers), inadequate O2 supply to the extremities - small vessel circulation issues

Question 21

can hypoxia occur despite adequate ventilation and perfusion

Answer 21

yes - if the tissue demand for oxygen outweighs the ability of blood to carry oxygen

Question 22

what is anaemia

Answer 22

iron deficiency = decrease in production of blood cells / haemorrhage = increase in loss

Question 23

how does anaemia contribute to hypoxia

Answer 23

decreased O2 content despite normal saturation and paO2 due to decreased Hb and HBO2

Question 24

how does carbon monoxide poisoning contribute to hypoxia

Answer 24

haemoglobin binding sites have a higher affinity for CO than O2
decreases O2 content, decreased SaO2, normal SpO2, normal PaO2, decreased HBO2, Hb normal

Question 25

does carbon monoxide poisoning produce cyanosis

Answer 25

no- carboxyhaemoglobin has a cherry red pigmentation

Question 26

what is the difference between hypoxemia and hypoxia

Answer 26

hypoxemia - low O2 in the blood

Hypoxia- low O2 in tissues