Renal Physiology: Urinary Concentration and Dilution Flashcards Preview

Physiology II > Renal Physiology: Urinary Concentration and Dilution > Flashcards

Flashcards in Renal Physiology: Urinary Concentration and Dilution Deck (31)
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1
Q

Hyposmotic body fluids create a ________ urine

A

dilute, (50 mOsm/L)

2
Q

Hyperosmotic body fluids create a ______ urine

A

concentrated (1200 mOsm/L)

3
Q

Can the kidneys regulated water excretion independently of solute excretion?

A

yes

4
Q

The countercurrent multiplier ensures high concentration gradient from ________ to the _________

A

corticomedullary border (proximal descending loop)

to the (papilla)

5
Q

The osmotic gradient in the ISF from the cortex to the medulla is used to do what?

A

remove water from urine in the collecting duct

6
Q

This portion of the loop of henle has the following characteristics…

  • no active transport of NaCl
  • very water permeable
A

Descending limb

7
Q

This portion of the loop of henle has the following characteristics…

  • Increases in thickness
  • actively reabsorbs NaCl
  • impermeable to water
A

ascending limb

8
Q

by what mechanism is NaCl pumped form the ascending limb?

A

active transport

9
Q

What is the largest possible gradient across the wall of the ascending limb?

A

200 mOsm

10
Q

What is the essential component to maintaining the countercurrent multiplier?

A

active transport of sodium and chloride ions

11
Q

What is meant by “countercurrent” in countercurrent multiplier

A

flow of current occurs in opposing direction through the two limbs

12
Q

What transporter present in the thick ascending limb of the LOH is responsible for active transport of ions from the ascending limb to the interstitium?

A

Na+, K+, 2Cl- transporter (NKCC2)

13
Q

what blocks the NKCC2 receptor, leading to duresis?

A

furosemide

14
Q

What stimulates NKCC2 leading to antiduresis?

A

ADH

15
Q

What ensures that the renal blood flow doesn’t wash away the concentrated solute in the medullary ISF?

A

Countercurrent exchange in the vasa recta

16
Q

Is the countercurrent exchange in the vasa recta active or passive?

A

passive

17
Q

As blood flows down a hairpin loop of vasa recta, what occurs? What about the ascending part of the hairpin?

A

NaCl into capillary

H20 diffused out of capillary

opposite for ascending

18
Q

the early distal convoluted tubule has what kind of transporter?

A

NaCl transporter NCC

19
Q

NCC transporter is blocked by what?

A

thiazide diuretics

20
Q

The early portion of the distal tubule is impermeable to what?

A

water

21
Q

What is the osmolarity of the early distal convoluted tubule?

A

50 mOsm

22
Q

The late distal tubule and collecting dict have what two cell types?

A

Principal cells

Alpha intercalated cells

23
Q

This cell type in the late distal tubule has the following characteristics…

Reabsorbes Na+
Secretes K+
Site of aldosterone action
Site of ADH action

A

principal cells

24
Q

This cell type in the late distal tubule has the following characteristics…

Secretes H+
Reabsorbes K+

A

Alpha intercalated cells

25
Q

What determines sodium reabsorption and potassium secretion?

A

Basolateral Na,K ATPase and apical ion channels

26
Q

What controls water and urea permeability in the collecting duct?

A

ADH

27
Q

High ADH increases the expression of what on the apical membrane, leading to what changes?

A

AQP2, increased water reabsorption, concentrated urine

28
Q

What percentage of sodium and water are reabsorbed in the proximal tubule, leaving tubular fluid ________?

A

60-80% reabsorbed

isosmotic fluid

29
Q

Where is water primarily reabsorbed, making fluid hyperosmotic?

A

descending limb of LOH

30
Q

Where does most NaCl reabsorption occur, making fluid hyposmotic?

A

ascending limb of LOH

31
Q

What is reabsorbed in the early distal tubule, leading to a hyposmotic fluid?

A

NaCl