Renal 8

Question 1

ECF K+ tightly regulated at ____ meq/L.

Answer 1

4.2

Question 2

Increase of only ____to____ mEq/L of K can cause cardiac arrhythmias, cardiac arrest, or fibrillation.

Answer 2

3 to 4

Question 3

What are the 2 mechs controlling K+ homeostasis?

Answer 3

1. Control of K+ distribution between the ECF and ICF

2. To keep [K+]ECF constant; rate of K+ excretion must equal rate of K+ input.

Question 4

High [K+]ECF

Answer 4

: Hyperkalemia

Question 5

Low [K+]ECF

Answer 5

: Hypokalemia

Question 6

Factors that shift K+ ____ cells:

• Insulin
• Aldosterone
• B2 Adrenergic stimulation (Epi and NE)
• Alkalosis
• Decreased Osm

Answer 6

into cells (Decreases [K}ECF)

Question 7

What is the mechanism for how the following factors shift K into cells?

• Insulin
• Aldosterone
• B2 Adrenergic stimulation (Epi and NE)
• Alkalosis

Answer 7

Increased Na-K ATPase activity

Question 8

What is the mechanism for how the following factors shift K into cells?
- Decreased ECF Osm

Answer 8

Dilute ICF, Decreased ΔEC for diffusion out of K+ cell

Question 9

Factors that shift K+ ____ cells:

• Increased Insulin deficiency
• Aldosterone insufficiency (Addison’s disease)
• B2 Adrenergic antagonists
• Acidosis
• Increased ECF Osm
• Strenuous exercise
• Cell lysis

Answer 9

Out of cells (Increases [K}ECF)

Question 10

What is the mechanism for how the following factors shift K out of cells?

• Increased Insulin deficiency
• Aldosterone insufficiency (Addison’s disease)
• B2 Adrenergic antagonists
• Acidosis

Answer 10

Decreased Na-K ATPase activity

Question 11

What is the mechanism for how the following factors shift K out of cells?
- Increased ECF Osm

Answer 11

Concentrate ICF, Increased ΔEC for diffusion out of K+ cell

Question 12

Where does the majority of the regulation of K+ occur?

Answer 12

Secretion in collecting duct

Question 13

Day to Day regulation of [K+]ECF is function of what portion of nephron?

Answer 13

late Distal Tubule/Collecting Duct

Question 14

High K+ intake leads to Increased K+ _________

Answer 14

secretion (principal cells)

Question 15

Low K+ intake leads to increased K+ _______

Answer 15

reabsorption (alpha intercalated cells)

Question 16

What are the 3 factors that determine the rate of K secretion by principal cells?

Answer 16

1. Na+/K+ ATPase Activity
2. Transepithelial potential difference (TEPD) between blood and lumen
3. Permeability of apical membrane for K+

Question 17

____ in [K]ECF results in increased K+ secretion

Answer 17

Increased [K]ECF

Question 18

_____ in aldosterone results in increased K+ secretion

Answer 18

INcreased Aldo

Question 19

____ in distal tubule flow rate results in increased K+ secretion

Answer 19

Increase in distal tubule flow rate

Question 20

Does alkalosis increase or decrease K+ secretion?

Answer 20

Increases K+ secretion

Question 21

Does acidosis increase or decrease K+ secretion?

Answer 21

Decreases K+ secretion

Question 22

The mechanisms for ____ K+ secretion are :

1. Increased Na+/K+ ATPase activity
2. TEPD is more lumen negative (due to increased Na+ reabsorption) which favors K+ secretion
3. Increased # K+ channels in apical membrane
4. Stimulates aldosterone secretion.

Answer 22

↑[K+]ECF

Question 23

Does aldosterone increase or decrease K+ secretion?

Answer 23

Increase K secretion

Question 24

Causes of ____ that increases K+ secretion:
Increased ECF volume
Na+ loading
Some Diuretics

Answer 24

INcreased distal tubule flow rate

Question 25

How does increased ECF volume lead to increased distal tubule flow rate?

Answer 25

Increased ECF volume -> Increased ANP release -> Increased GFR -> Decreased Na and K reabsorption -> Increased distal tubule flow rate

Question 26

The mechanisms for _____ that causes increased K+ secretion include: 1. Increased tubule flow rate keeps luminal K+ lower, maintaining ΔC for secretion 2. Increases #BK channels in apical membrane

Answer 26

INcreased distal tubule flow rate

Question 27

Causes of _____ include: Renal failure  Decreased distal nephron flow (heart failure, severe volume depletion, NSAID, etc.)  Decreased aldosterone or decreased effect of aldosterone - adrenal insufficiency - resistance to aldosterone - K+ sparing diuretics (spironolactone)  Metabolic acidosis (hyperkalemia is mild) Diabetes (kidney disease, acidosis, insulin)

Answer 27

Hyperkalemia

Question 28

``` Causes of _____ include: Very low intake of K + GI loss of K+ - diarrhea Metabolic alkalosis Excess insulin Increased distal tubular flow -salt wasting nephropathies -osmotic diuretics - loop diuretics Excess aldosterone ```

Answer 28

Hypokalemia

Question 29

_____ is a drug that increases urine volume output.

Answer 29

Diuretic

Question 30

Most diuretics act by _____ Na+ reabsorption from some part of the nephron

Answer 30

decreasing

Question 31

_______ causes diuresis by an osmotic mechanism.

Answer 31

Natriuresis

Question 32

Most common reason for use of diuretics is to ______

Answer 32

reduce ECFV

Question 33

Reducing ECFV via diuretics _____ edema and _____ MAP

Answer 33

Reduces edema; reduces MAP

Question 34

______ Increase Solute and H2O Excretion until Compensatory Mechanisms Re-establishes Balance

Answer 34

Diuretics

Question 35

____ Transport is a Target for many Diuretics

Answer 35

Na+ transport

Question 36

_____ diuretics: Nonabsorbable substance is filtered (ex. mannitol, sucrose). Osmols in tubular fluid require water. Similar to effects of endogenous substances (glucose, urea). -Diuresis caused by hyperglycemia. May increase excretion of other solutes.

Answer 36

Osmotic diuretics

Question 37

______ (diuretics): Acetazolamide. More than 80% of HCO3- reabsorption and H+secretion occurs in proximal tubule. block Na+reabsorption (and H+secretion) indirectly.

Answer 37

Carbonic Anhydrase Inhibitors

Question 38

At what part of the nephron do carbonic anhydrase inhibitors act?

Answer 38

Proximal tubule

Question 39

At what part of the nephron do loop diuretics act?

Answer 39

Thick ascending limb

Question 40

Furosemide, ethacrynic acid, bumetanide Inhibit Na+-K+-2Cl- - cotransport pump on luminal membrane of TAL of Henle. Most powerful diuretics available (30% of GFR may appear in urine!). Overwhelm downstream absorptive capacity. Disrupt countercurrent multiplier.

Answer 40

Loop diuretics

Question 41

At what part of the nephron do thiazide diuretics act?

Answer 41

Early distal tubule

Question 42

_____ diuretics increase osmolarity of tubular fluid in the proximal tubule

Answer 42

Osmotic

Question 43

_____ diuretics decrease Na-K-2Cl cotransport in the TAL of loop of henle

Answer 43

Loop diuretics

Question 44

_____ diuretics decrease Na-Cl cotransport in the early distal tubule

Answer 44

Thiazide diuretics

Question 45

______ diuretics decrease H secretion, HCO3 absorption (decreases Na-H exchange) in the proximal tubule

Answer 45

Carbonic anhydrase inhibitor

Question 46

_____ diuretics decrease Na absorption and K secretion in the late distal tubule and collecting duct

Answer 46

Aldosterone antagonists

Question 47

_____ diuretics block ENaC and decrease K secretion in the late distal tubule and collecting duct

Answer 47

Na channel blocker

Question 48

Which 2 classes of diuretics are K sparing diuretics?

Answer 48

Aldosterone antagonists and Na channel blocker

Question 49

_____ diuretics: cause K+ loss Increasing flow rate of filtrate through distal nephron increases K+ secretion. Keeps luminal K+ concentration low supporting secretion Hypokalemia may result.

Answer 49

K sparing diuretics

Question 50

_____ diuretics reduce levels of Na+/K+ ATPase, ENaC, K+ channel.

Answer 50

Aldosterone antagonists

Question 51

____ diuretics reduce Na+ uptake, Na+/K+activity, K+secretion

Answer 51

ENaC blockers