Hi Joanna,
This was a question from a passage:
A lower-than-normal blood pressure will cause which of the following effects on the rate of plasma clearance of Substance A? (Substance A is similar to glucose)
An increase, because the concentration of Substance A in the urine will increase
An increase, because the ADH levels will be very low
A decrease, because the decreased rate of urine output will allow more reabsorption by the kidney
A decrease, because ADH levels will be very high
a) what is meant by plasma clearance....is this what happens in the glomerulus?
Plasma clearance refers to the removal of the drug from the blood - in this case the implication is into the urine through the glomerulus (but you can have plasma clearance into other pathways).
b) when ions and water are secreted from loops of Henle - where are they reabsorbed to? The vasa recta (i.e. the blood) or to the kidney tissue?
When ions and salts are reabsorbed, they are ultimately returned to the blood. I believe that this should be the vasa recta.
c) Does blood pressure increase because juxtaglomerular apparatus recognizes BP is low and therefore more water is reabsorbed into the VASA RECTA specifically?
When you have water reabsorption, your blood pressure is going to go up because you have a larger volume of fluid in a relatively constant volume of your blood vessels. I do not understand the significance you are placing on the Vasa recta specifically, as this reabsorption will balance out eventually over all the blood (via diffusion). However, this overall seems reasonable to me.
Katt