Regulation of Water and Na+ Reabsorption

Question 1

What happens to the FF of Na+ in a patient who is hypovolemic?

Answer 1

FF, decreases. FF= GFR/RBF (GFR decreases)

Question 2

What happens to the FF of Na+ in a patient who is hypervolemic?

Answer 2

FF, increases. FF= GFR/RBF (GFR increases)

Question 3

What is antidiuresis?

Answer 3

High Levels of ADH; retaining water (opposite effect of diuretics)

Question 4

What is diuresis?

Answer 4

Low levels of ADH; secreting water (increased free water clearance)

Question 5

Where would the tubular fluid/plasma osmolarity being the lowest in a person who is dehydrated?

Answer 5

RIght after the Ascending limb of the loop of Henle; as water is impermeable in this segment, causing dilution of the tubular fluid

Question 6

What does an increased filtration fraction represent?

Answer 6

It represents either an increased GFR or a decreased RPF; both would decrease peritubular hydrostatic pressure and increase osmotic pressure, thus increase reabsorption into the peritubular capillaries

Question 7

What is the action of Urodilatin?

Answer 7

It promotes Na+ excretion

Question 8

What is a major stimulus for Aldosterone release?

Answer 8

Hyperkalemia; (Resulting Aldosterone, increases Na+ reabsorption at the principle cells, subsequently causing K+ secretion

Question 9

Intrarenal prostaglandins suppress Na+ reabsorption at what sites?

Answer 9

TAL & Cortical collecting duct

Question 10

Urodilatin suppresses Na+ and water reabsorption at what site?

Answer 10

MEdullary collecting duct