Lecture 18 - Renal Regulation Of [ion] Flashcards Preview

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Flashcards in Lecture 18 - Renal Regulation Of [ion] Deck (43):
1

The normal [K]ecf is _______.

A. 142 mEq/L ( 0.3mEq/L)
B. 4.2 mEq/L ( 0.3mEq/L)
C. 150 mEq/L
D. 5 mEq/L

B. 4.2 mEq/L ( 0.3mEq/L)

2

ECF contains approximately what % of body K?

A. 1%
B. 5%
C. 25%
D. 79%

A. 1%

3

An increase in ECF [K] of _____ may lead to the development of cardiac arrhythmia.

3-4 mEq/L

4

Normal ICF [K] is _______.

A. 140 mEq/L ( 0.3mEq/L)
B. 4.2 mEq/L ( 0.3mEq/L)
C. 150 mEq/L
D. 5 mEq/L

A. 140 mEq/L ( 0.3mEq/L)

5

ECF potassium is directly controlled in what two portions of the nephron?

DCT and collecting ducts

6

Aldosterone is a stimulator/inhibitor of potassium secretion

stimulator (increased aldosterone increases potassium loss)

7

Potassium reabsorption occurs in the:

A. PCT and late DCT
B. Ascending limb of LoH
C. Collecting duct and PCT
D. PCT and ascending LOH

D. PCT and ascending LoH

8

Potassium secretion/sodium reabsorption occurs via the ____ in principal cells.

Na/K ATPase

Na+ is reabsorbed; K+ is secreted

9

K+ flow through ____ on the apical membrane

K+ channel

10

High K+ plasma produces an ____ in aldosterone, as well as direct K+ secretion in the ______.

Increase
cortical collecting tubules

11

Approximately 50% of Ca2+ is found ______ proteins.

bound to transport

12

Changes to ___ will affect the binding of Ca2+ to transport proteins

A. Cell size
B. Blood volume
C. Body temp
D. pH

D. pH (changing pH will change proteins)

13

Acidosis results in a ____ of protein bound Ca2+.

A. Decrease
B. Increase
C. No change

A. decrease

14

Release of _____ causes an increase in blood calcium levels.

PTH

15

PTH works to raise blood [Ca2+] by _____.

increasing bone breakdown; increasing Ca2+ absorption in the GI tract; increased Vit. D3 activation; increased tubular reabsorption (indirectly)

16

What % of Ca2+ is reabsorbed by the PCT?

A. 99%
B. 65%
C. 50%
D. 22%

B. 65%

17

20% of calcium is absorbed in the PCT by what routes?

Transcellular
- Electrochemical gradient "pushes" Ca2+ out of the lumen
- Basolateral Ca2+ ATPase
- Basolateral Na+/Ca2+ exchanger

18

Calcium resorption in the loop of Henle is in the _______.

A. Thick descending
B. Thick ascending
C. Thin descending
D. Thin ascending

B. Thick ascending

19

50% of calcium absorption in the thick ascending loop of Henle occurs by paracellular routes. The remaining 50% occurs through the transcellular route and is stimulated by ______.

A. Calcitonin
B. PTH
C. Aldosterone

B. PTH

20

T/F: Ca2+ reabsorption occurs in all portions of the nephron.

False; Ca2+ reabsorption is relegated to the PCT, DCT, and thick ascending Loop of Henle

21

Ca2+ reabsorption of calcium is accomplished by ____ stimulated by PTH.

A. Sodium/Calcium exchanger on the basolateral side
B. Sodium/Calcium exchanger on the apical side
C. Calcium ATPase on the basolateral side
D. Calcium ATPase on the apical side

C. Calcium ATPase on the basolateral side

22

Phosphate excretion occurs via what mechanism?

overflow (Tmax=0.1mM/min)

23

Resorption of phosphate occurs via a ____cellular route.

A. paracellular
B. trans

B. trans

24

____ assists in both resorption of Ca2+ and PO4

PTH

25

PTH causes phosphate to exceed its transport maximum; this results in _____.

phosphate excretion

26

Of insulin, chatecholamines, and aldosterone, which produce potassium uptake?

all three

27

Describe the mechanism of action of aldosterone in regard to potassium reabsorption

1) Aldosterone stimulates Na/ATPase pumps in principal cells
2) Luminal membrane permeability for K+ increases
3) Extracellular [K+] increases

28

Describe the effect of metabolic acidosis on ECF [K+]

Acidosis (decreased pH= increased [H+]) produces changes to the proteins comprising the Na/KATPase pumps. This produces decreased re-uptake of K+ into the cells.

29

Describe the effect of cell lysis on ECF [K+]

Increased, as lysis of cells releases large amounts of the ICF K+

30

Describe the effect of metabolic alkalosis on ECF [K+]

Decreases extracellular K+

31

Principle cells are responsible for (secretion/absorption) of K+.

Secretion

32

Principal cells are located in what portion of the nephron?

A. DCT
B. Cortical collecting tubule
C. Medullary collecting tubule
D. DCT & Cortical collecting tubule

D. DCT and cortical CT

33

Principle cells secrete K+ what what mechanism?

Na/K ATPase on the basolateral membrane

passive diffusion of K+ into tubular lumen

34

Intercalated cells resorb K+ during what situation?

A. Increased ECF K+
B. Decreased ECF K+
C. Decreased tubular K+

B. Decreased ECF K+ (K+ depletion)

35

Intercalated cells move K+ and what other ion during K+ depletion? Is this sym- or anti-port?

H+; anti-port (H+ is secreted)

36

_____ intercalated cells secrete K+

Type B

37

______ of the late distal and collecting tubules reabsorb K+

Type A intercalated cells

38

By what mechanisms are internal [K] regulated?

Decreased ECF [K]
1) insulin - increases cellular K uptake
2) aldosterone - stimulates cellular K uptake
3) beta-adrenergic stimulation - increases cellular K uptake

Increased ECF [K]
4) acid/base disturbances - decreased pH can increase [K]ecf. The mechanism is unclear, but it's believed to arise from decreased Na/KATPase function 2/2 acidosis*
5) cell lysis - spills out ICF potassium
6) exercise - myocytes release K with strenuous exercise
7) increased ECF Osmolarity - Complicated! Increased ECF Osmolarity promotes diffusion of water out of cells. This, in turn, raises ICF [K]. When this increase in ICF [K] occurs, K flows down its gradient into the ECF fluid.

*Remember that pumps are proteins. A change in pH affects the structure of the protein.

39

Potassium excretion is primarily controlled by the _____ of the late distal and cortical collecting tubules.

Prinicpal (Think "Principal Potassium")

40

Outline the process of potassium excretion by the kidneys.

1) Increased blood [K] occurs
2) K is absorbed into renal tubule cells by basolateral Na/KATPase
3) ICF [K] is raised
4) K flows down its gradient into the tubular lumen
- occurs in prinicpal cells
- "ROMK"-renal outer medullary potassium channels
- "BK"- "Big Potassium" channels

41

In severe K depletion, the ____cells act to resorb K.

A. Principle cells
B. Type A Intercalated cells
C. Type B Intercalated cells

B. Type A Intercalated cells

42

In cases of excess potassium, the _____ act in concert with principal cells to secrete potassium.

A. Principle cells
B. Type A Intercalated cells
C. Type B Intercalated cells

C. Type B Intercalated cells

These are under control of aldosterone

43

This hormone sees its secretion increased when ECF [K] begin to rise.

A. ADH
B. Epinephrine
C. Aldosterone
D. Erythropoietin

C. Aldosterone