From Bio Chapter 3 on the Kidney, the question asks to find the graph that best represents the plasma osmolarity (X-axis) of the blood and the plasma concentration of antidiuretic hormone (Y-axis).
The answers include the following curves (try to get the best general shape example):
A. sigmoid function with flat vertical region like the titration of a strong acid with a strong base: at one point there is a huge increase in ADH before plasma osmolarity is really impacted
B. flat horizontal region like a titration curve (see general curve below going through the origin: the idea that ADH increases in 2 phases as ADH concentration stays the same before increasing again with increased plasma osmolarity? the shape is similar to this:
C. increasing log function like saturation kinetics. graph shape similar to this:
D. graph where X increases and Y stays the same until 1 point where there is a linear positive increase in the graph (see graph below)
The answer given by TBR is that the best graph is the sigmoid function (A) with a flat vertical region in that there is a quick response from ADH and as ADH is being released the osmolarity doesn't change much.
Why is it not choice D where there is a threshold at which plasma osmolarity is sensed by osmoreceptors to release ADH?
The answers include the following curves (try to get the best general shape example):
A. sigmoid function with flat vertical region like the titration of a strong acid with a strong base: at one point there is a huge increase in ADH before plasma osmolarity is really impacted
B. flat horizontal region like a titration curve (see general curve below going through the origin: the idea that ADH increases in 2 phases as ADH concentration stays the same before increasing again with increased plasma osmolarity? the shape is similar to this:
C. increasing log function like saturation kinetics. graph shape similar to this:
D. graph where X increases and Y stays the same until 1 point where there is a linear positive increase in the graph (see graph below)
The answer given by TBR is that the best graph is the sigmoid function (A) with a flat vertical region in that there is a quick response from ADH and as ADH is being released the osmolarity doesn't change much.
Why is it not choice D where there is a threshold at which plasma osmolarity is sensed by osmoreceptors to release ADH?