UW graph that I don't understand. Can someone please explain?

[Tristy]

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It's a graph of blood oxygen content (Y-axis) vs vascular resistance and asks which organ would show a behavior like such.















The curve goes downwards exponentially (trying to be as graphic as possible). In their explanation, they basically say that arterial resistance goes up as blood oxygen goes down (hypoxic vasoconstriction, I understant that).

But the curve shows otherwise, at least to me, and I can't figure out their reasoning...The way I see it is that resistance goes down as oxygen goes down (from looking at the curve). Can someone please explain?

 

[Captopril]

It's a graph of blood oxygen content (Y-axis) vs vascular resistance and asks which organ would show a behavior like such.















The curve goes downwards exponentially (trying to be as graphic as possible). In their explanation, they basically say that arterial resistance goes up as blood oxygen goes down (hypoxic vasoconstriction, I understant that).

But the curve shows otherwise, at least to me, and I can't figure out their reasoning...The way I see it is that resistance goes down as oxygen goes down (from looking at the curve). Can someone please explain?

My internet sucks so the image isn't loading. The organ in question is the lungs though. As PaO2 drops, vasoconstriction occurs in an effort to shunt the blood to areas of higher ventilation (I assume the apices?). Must be an impt concept because it was in FA, RR Path, and UW.

 

[Scaredshizzles]

My internet sucks so the image isn't loading. The organ in question is the lungs though. As PaO2 drops, vasoconstriction occurs in an effort to shunt the blood to areas of higher ventilation (I assume the apices?). Must be an impt concept because it was in FA, RR Path, and UW.

It is an important concept....The strong association between sleep apnea and CHF is thought to at least in part be related to this....Ongoing pulmonary hyperetension from hypoxic vasoconstriction at night secondary to sleep apnea leads to increased RV pressures and hypertrophy and eventual right sided HF.

But I can't see the graph, the way the OP describes the graph, it would be correct. The graph should show increasing resistence with decreasing PaO2. If the Y-axis is arterial O2 and the X-axis in vascular resistence, then as you move along the X-axis you should having increasing resistence and the associated decrease arterial oxygen (i.e. a downward sloping graph)....The graph may be confusing though since resistence should really be the dependent variable the way we conceptualize it, and should be plotted on the Y-axis instead of the X-axis.