gas transport Flashcards
dissociation curves: explain respiratory gas dissociation curves and how these are affected by physiological and environmental changes
why aren’t O2 dissociation curves linear
ensures that high saturation occurs in lungs but that in systemic circuit a lot of oxygen can be unloaded when really needed (during exercise much greater scope for tissues taking O2 out of what is arriving)
at rest what % of oxgen is removed in systemic circulation
25%
what is P50
partial pressure of oxygen when HbO2 is 50%
what type of affinity does left shift indicate
high affinity
4 things that can increase O2 affinity and cause left shift
hypothermia, alkalosis, hypocapnia, decreased 2,3-DPG
4 things that can decrease O2 affinity and cause right shift
hyperthermia, acidosis (Bohr effect), hypercapnia, increased 2,3-DPG
what 4 things affect P50
temperature, pH, CO2, 2,3-DPG
what does an upwards shift indicate
polycythaemia (increased oxygen carrying capacity)
what does a downwards shift indicate
anaemia (impaired oxygen carrying capacity)
what does a down and leftwards shift indicate (CO poisoning)
decreased capacity and increased affinity resulting from increased HbCO (carboxyhaemoglobin) caused by CO poisoning, which when bound caused oxygen to bind more strongly
x and y axis of oxygen dissociation curve
x: PaO2 (kPa), y: HbO2 saturation (%)
what do amino acid Hb chains with negative charges act as
proton acceptors
describe CO2 dissociation curve
practically linear, with slightly higher concentration in venous blood than arteries; the more oxygenated the Hb, the less CO2 accepted
what does the shape of the CO2 dissociation curve indicated about significance of dissolved CO2
not as significant as not sigmoid shaped curve
what happens to oxygen dissociation curve in older age
shifts right
