Physiology 2: Osmolality Regulation, Azotemia, Bicarbonate

Question 1

Effects of Increased ECF Osmolality?

Answer 1

correction requires a positive water balance; increased thirst and decreased renal water excretion.

Question 2

Effects of Decreased ECF Osmolality?

Answer 2

correction requires negative water balance; decreased thirst and increased water excretion.

Question 3

Which limb (thin descending or thin ascending) of the Loop of Henle is most important to the movement of water?

Answer 3

The Thin DESCENDING limb as the ascending is impermeable to water.

Question 4

What are the 4 elements of the system that controls body fluid osmolality?

Answer 4

Loop of Henle and vasa recta
Variable permeability of the collecting ducts to water
Osmoreceptors
ADG

Question 5

The vasa recta pick up relatively more/relatively less solute than water in the kidney?

Answer 5

Relatively more solute, causing the blood leaving the vasa recta to have a slightly higher osmolality.

Question 6

What happens to the sensitivity of ADH with hyper and hypovolemia?

Answer 6

Hyper: depresses the sensitivity

Hypo: increases the sensitivity

Question 7

What is the relative sensitivity of ADH system in osmotic changes vs. volume changes?

Answer 7

Changes in osmolality cause dramatic increases in ADH in changes from 0-5%.

Changes in volume causes changes in ADH release but only after changes of 10% or greater.

**Osmotic is more sensitive but Volume has more gain (requires more input).