Loop of Henle, Distal tubule and Collecting Duct - Rao Flashcards Preview

Nephrology > Loop of Henle, Distal tubule and Collecting Duct - Rao > Flashcards

Flashcards in Loop of Henle, Distal tubule and Collecting Duct - Rao Deck (26):
1

Describe the cells of the thin descending limb.

Thin epithelial cells with few mitochondria

2

What is the tonicity of the interstitial environment compared to plasma?

Interstitial environment is hyperosmotic compared to plasma

3

Describe the permeability to water, NaCl, and urea in the thin descending limb.

Water - highly permeable
NaCl - impermeable
Urea - impermeable

4

Describe the permeability to water, NaCl, and urea in the thin ascending limb.

Water - highly impermeable
NaCl - permeable (strong reabsorption 20-25%)
Urea - impermeable

5

Describe the cells of the thick ascending limb.

Thick epithelial cells with many mitochondria

6

What transporters are present in the thick ascending limb?

Na K 2Cl cotransport - apical
Na K ATPase antitransport - basolateral
Cl channel - basolateral
K Cl cotransport - basolateral
K channel - apical (K -> lumen)

7

What can inhibit NaK2Cl transporter?

Diuretic agents with high affinity for Cl site
Furosemide, bumetanide

8

What is the net result of fluid passing through the DCT and CT?

Dilution of tubular fluid (if impermeable to water)

9

How is sodium reabsorbed in the DCT?

Electrically conductive Na channels
Na / Cl cotransporter

10

What diuretics block electrically conductive Na channels?

Amiloride
Triamterene

11

What diuretics inhibit Na / Cl cotransporters?

Thiazide diuretics

12

What is the driving force for potassium secretion in the DCT and CT?

High intracellular concentration of K caused by Na K ATPase
Lumen-negative transepithelial voltage

13

What are regulatory factors affecting K secretion?

Increased flow by diuretics cause increased K secretion
Increased Na reabsorption increases K secretion

14

What is the affect of loop diuretics, thiazides, and amilorides on K secretion?

Loop diuretics - increase K secretion
Thiazides - no change
Amilorides - no change

15

How is Na reabsorbed in the CT?

Electrically conductive Na channels

16

Where is aldosterone synthesized and where does it act?

Synthesized - adrenal cortex
Act - DCT and CT

17

What are aldosterone's actions?

Increase Na reabsorption
Increase K secretion

18

What is Addison's disease?

Complete lack of aldosterone
Increased urinary excretion of NaCl

19

What is Conn's Syndrome?

Aldosterone secreting tumor
Increased Na reabsorption / K secretion
Hypokalemia, hypernatremia, hypertension

20

What factors stimulate aldosterone?

Reduced ECF volume
Reduced plasma Na
Increased plasma K
Increased plasma AT II
Trauma / stress

21

What is reabsorbed and secreted in the DCT and CD to maintain acid-base balance?

Bicarbonate - reabsorbed
Protons - secreted

22

What do principal cells do?

Na - reabsorb
K - secrete

23

What do intercalated cells do?

Proton - secrete
Bicarbonate - secrete (some cells)

24

How are protons secreted in the DCT and CD?

Under acidosis conditions
Proton activated ATPase (luminal; proton pumped to lumen)
H K ATPase (luminal; H to lumen; K to cell)
HCO3 / Cl exchanger (basolateral; HCO3 to ISF; Cl to cell)

25

Under what conditions and how is bicarbonate secreted?

Under alkalosis condition
H ATPase (basolateral; proton to ISF)
HCO3 / Cl exchanger (luminal; HCO3 to lumen)
alpha cell - luminal proton channel
beta cell - luminal bicarbonate channel

26

What sitmulates distal nephron calcium reabsorption?

Parathyroid hormone