RESP- Oxygen Transport Flashcards
how is oxygen transported around the body
bound to haemoglobin and dissolved in plasma
how is carbon dioxide transported in the body
as bicarbonate, bound to haemoglobin, dissolved in plasma
is more oxygen bound to haemoglobin or dissolved in the plasma
bound to haemoglobin - oxygen has low solubility in plasma
what is the partial pressure of oxygen a measure of
PaO2
how much oxygen is in the plasma
what is total oxygen content (CaO2) a measure of
volume of oxygen carried in each litre of blood- includes oxygen bound to haemoglobin and dissolved in plasma
what is oxygen saturation a measure of (SaO2)
proportion of haemoglobin binding site which currently have oxygen bound to them
what is the oxygen-haemoglobin dissociation curve
proportion of saturated haemoglobin plotted against the partial pressure of oxygen
what shape is the oxyhaemoglobin dissociation curve
sigmoidal
explain the oxyhaemoglobin dissociation curve
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
how is oxygen released from haemoglobin to respiring tissues
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
what is P50 in relation to the oxygen dissociation curve
partial pressure of oxygen in blood when haemoglobin is 50% saturated
why is P50 an important measure
some physiological disease processes may shift the dissociation curve to the left or the right changing the P50 value
therefore this value is comparative
what are the effects of shifting the oxyhaemoglobin curve to the right
right shift - lower oxygen affinity - so P50 occurs at a higher PO2 - increased oxygen unloading
what are the effects of shifting the oxyhaemoglobin curve to the left
left shift - higher oxygen affinity - P50 occurs at a lower ppO2 - impaired oxygen unloading
what factors can shift the oxyhaemoglobin dissociation curve to the left / the tight
left - decreased pCO2, decreased temperature, decreased 2,3-DPG, increased pH, HbF
right - increased pCO2, increased temperature, increased 2,3-DPG, decreased pH
what is the bohr effect
the effect of pH, CO2 and temperature on oxygen affinity
how is HbO2 affinity different in:
the lungs
resting tissue
working tissue
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
what colours do oxyhaemoglobin and deoxyhaemoglobin appear
oxyhaemoglobin - red
deoxyhaemoglobin - blue
what produces the colour of cyanosis
purple discoloration of the skin due to build up of deoxyhaemoglobin
what is the difference between central cyanosis and peripheral cyanosis
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
can hypoxia occur despite adequate ventilation and perfusion
yes - if the tissue demand for oxygen outweighs the ability of blood to carry oxygen
what is anaemia
iron deficiency = decrease in production of blood cells / haemorrhage = increase in loss
how does anaemia contribute to hypoxia
decreased O2 content despite normal saturation and paO2 due to decreased Hb and HBO2
how does carbon monoxide poisoning contribute to hypoxia
haemoglobin binding sites have a higher affinity for CO than O2
decreases O2 content, decreased SaO2, normal SpO2, normal PaO2, decreased HBO2, Hb normal
does carbon monoxide poisoning produce cyanosis
no- carboxyhaemoglobin has a cherry red pigmentation
what is the difference between hypoxemia and hypoxia
hypoxemia - low O2 in the blood
Hypoxia- low O2 in tissues
