Renal: Urine Concentration and Dilution Mechanisms

Question 1

Osmoreceptors that sense osmolarity

Answer 1

Osmoreceptors

Question 2

ADH is released from which Pituitary Gland?

Answer 2

Posterior Pituitary

Question 3

True/False:

Changes in Blood Osmolarity changes ADH release

Answer 3

True

Question 4

What Hormone concentrates Urine?

Answer 4

ADH

Question 5

Which part of the Loop of Henle is the concentrating segment?

Answer 5

Descending limb of Loop of Henle

Question 6

Which part of the Loop of Henle is the diluting segment?

Answer 6

Thick Ascending limb of Loop of Henle

Thin Ascending limb of Loop of Henle

Question 7

What is the difference between Nephrons?

Answer 7

Placement and Length of Loop of Henle

Question 8

Concentrations _____ while moving down Loop of Henle

Answer 8

Increase. Up to about 1200mOsm/L

Question 9

pumps against 200mOsm gradient. 200mOsm maximum difference between outside and inside (higher on the outside)

Answer 9

Sodium-Potassium-2 Chloride Transporter (mostly on Ascending but some on Descending)

Question 10

Countercurrent Mutltiplier System

Answer 10

Loop of Henle

Question 11

Countercurrent Exchanger System

Answer 11

Vasa Recta

Question 12

Isoosmotic level

Answer 12

300mOsm/L

Question 13

Urea contributes to hyperosmotic medulla. Urea contributes how much of the osmolarity of renal medullary interstitium?

Answer 13

40%

Question 14

Which parts of the Nephron are relatively impermeable to Urea?

Answer 14

Ascending Limb of Loop of Henle, Distal tubule, and Cortical Collecting Duct are relatively impermeable to urea

Question 15

Which part of the Collecting Duct is very permeable to Urea?

Answer 15

Inner-medullary Collecting Ducts very permeable to urea (even more so with ADH)

Question 16

Which parts of the Nephron have some reabsorption to Urea?

Answer 16

Proximal Tubule

Question 17

Which part of the Nephron Urea diffuses into?

Answer 17

Descending Limb of Loop of Henle

Question 18

Urea recycling

Answer 18

Urea moves in and out of Nephron

Question 19

Vasa Recta surrounds which type of Nephron?

Answer 19

Juxtamedullary Nephrons

Question 20

Peritubular Capillaries surrounds which type of Nephron?

Answer 20

Cortical Nephrons

Question 21

Difference between Vasa Recta and Loop of Henle?

Answer 21

Loop of Henle makes the concentration gradient

Vasa Recta aids the Loop of Henle function, preserves concentration gradient

Question 22

What helps to preserve hyperosmolarity of the renal medulla?

Answer 22

Vasa Recta

Question 23

What are the 2 characteristics of the Vasa Recta?

Answer 23

1. Medullar blood flow is low

2. Vasa Recta serve as countercurrent exchangers

Question 24

How does the Vasa Recta preserve the gradient?

Answer 24

As solutes move into blood, solutes move back into the interstitium instead of “washing out” gradient

Question 25

What 4 factors impact Urine Concentration?

Answer 25

1. Plasma level of ADH
2. Osmolar concentration of interstitial fluid surrounding the collecting ducts
3. Urea recycling
4. Vasa recta

Question 26

Dehydration leads to a more ______ Urine

Answer 26

Concentrated (higher osmolarity)

Question 27

Hydration leads to a more _______ Urine

Answer 27

Diluted (lower osmolarity)