1) Draw a schematic diagram showing how the osmolarity of the
“lumen” solution changes as it moves through Bowman’s capsule, then
the proximal tubule, the descending loop of Henle, the bottom
portion of the loop of Henle, the ascending portion of Henle, the
distal tubule and the collecting duct. Do this both in the presence
and absence of antidiuretic hormone (two separate diagrams). Be
sure to put numbers indicating osmotic values at appropriate
portions of the lumen. Also show the osmotic gradient that exists
in the extracellular matrix of the kidney, going from the top of
the cortex to the bottom of the medulla; be sure to put in numbers.
In a third diagram, draw an “aberrant” kidney in which at the top
of the medulla, the extracellular osmotic gradient was 1400 mosm
and at the very end of the loop of Henle the osmolarity was 300.
Draw the direction of the flow of water and salts as they move
through the loop of Henle in this aberrant condition.
(2) What is the osmotic pressure difference that exists from the
top of the cortex to the bottom of the medulla in the human kidney?
Give an answer in both atmospheres and mm Hg.
(3) Draw a schematic diagram showing the flow of water and salts
in the proximal tubule of the kidney. In this diagram, put
the lumen on the left side of the diagram and the extracellular
fluids on the right side of the diagram. Indicate where
the lumen is, where the extracellular fluid is, where the apical
portion of the cell is, and show the location of the proteins that
are responsible for the movement of water and salts and glucose
reabsorption in this area of the kidney
(4) Draw a graph showing the quantitative relation between the
amount of glucose in the plasma vs. the amount of glucose absorbed
in the kidney