Potassium Metabolism - Showkat

Question 1

Where is the majority of K stored?

Answer 1

Intracellularly

Question 2

What are the major mechanisms for K excretion and the percentages?

Answer 2

Renal (90-5%) and GI excretion (5-10)

Question 3

What is the concentration of K inside the cell

Answer 3

120-140 meq/dl

Question 4

What is the internal vs external balance of potassium?

Answer 4

Internal is the regulatino of pot. between ICF and ECF

External is the regulation of total body K through intake and excretion

Question 5

Where is the only place that K is secreted?

Answer 5

Collecting Duct

Question 6

What percentage of K is reabsorbed in the PCT?

Answer 6

65%

Question 7

In the TALH, what transporter is responsible for the movement of K and where is it taking it?

Answer 7

It’s reabsorbing it into the luminal cell by the NaK2Cl transporter

Question 8

What are the actions of the principal cells?

Answer 8

Bring sodium in from the lumen, use the NaK AtPase pump on the blood side, having the ROMK channel on the lumenal side

Question 9

Explain the movement of K in relation to aldosterone?

Answer 9

Aldosterone is secreted into the lumenal cell, becoming active and activating the NaK ATPase on the basolateral membrane. This brings 2K into the cell for 3 Na outside, creating a high concentration of K in the cell. Then the Aldosterone also upregulates the activity of ROMK channels, releasing K into the urine.

Question 10

Explain the relationship between Na, K and having an electronegative lumen

Answer 10

When Na is absorbed from the lumen, it leaves an electronegative lumen, which then makes the K drawn to the lumen to compensate for the loss of + charges

Question 11

Wht are the three factors affecting K secretion?

Answer 11

concentration gradient
electrical gradient (depending on Na reabsorb.)
K permeability (ROMK channel depending on alodsterone)

Question 12

If you Increase the distal delivery of K, what happens to the K secretion? Why?

Answer 12

It increases secretion. This is because of the secreting mechanism that is in place only in the collecting duct

Question 13

How can you increase K excretion?

Answer 13

Increased K and Na delivery to the distal tubule and CD.

Potassium secretion regulated by aldosterone

Question 14

What are causes of decreased renal potassium secretion?

Answer 14

renal failure
distal tubular dysfunction
decreased distal tubular flow
hypoaldosteronism

Question 15

what disorders can lead to increased K secretino

Answer 15

prolong vomiting, nasogastric suction
bartters
gitelmans
hyperaldosteronism

Question 16

What transport is the main mechanism for regulation of K levels between ICF and ECF

Answer 16

NaK ATPase

Question 17

What factors affect the internal potassium balance?

Answer 17

plasma potassium concentration
insulin
epinephrine

Acid-Base disturbance
plasma tonicity
cell lysis and cell proliferation

Question 18

which receptor triggers increased NKATPase activity? Which receptor decreases it?

Answer 18

Beta2 receptors increase (insulin)

Alpha receptors decrease (epinephrine?)

Question 19

Is hypo or hyper kalemia seen in extracellular alkalosis? acidosis?

Answer 19

in alkalosis, the H has moved into the ecf, pushing the K into the cell, creating hypokalemia of the plasma

in acidosis, the H has moved into the cell, pushing the K into the plasma, causing hyperkalemia

Question 20

How does plasma tonicity affect K balance?

Answer 20

An increase in plasma tonicity (due to increased Na) will cause K to move into the ECF, to bring water with it. Causing more K to be in the ECF than in the ICF

THEN, loss of intracellular water increases the intracellular K concentration, causing an increased gradient when compared to the ECF. This then causes the K to flow passively out of the potassium channel.

Question 21

How does cell lysis affect K balance?

Answer 21

When cells lyse, intracellular K is released into extracellular space

Question 22

How does cell proliferation cause K balance changes?

Answer 22

K is rapidly taken up by proliferating cells, casuses ecf k concentration to fall.

Question 23

what could cause the cell lysis that leads to an increased K concentration in the ecf?

Answer 23

muscle injury, rhabomyolysis, rbc injury - hemolysis

Question 24

What are three general causes of hyperkalemia?

Answer 24

Excess Intake
Decreased Renal Excretion
Internal Redistribution

Question 25

What are some specific causes of hyperkalemia?

Answer 25

Oral intake of K,
Acute or Chronic Renal Failure
Decreased Distal Tubular Flow
Hypoaldosteronism
Insulin Deficiency (redistri)
Beta2 blockage (redistr)
hypertonicity (redist)
acidemia (redistri
Cell lysis (reddistr

Question 26

What are some ekg manifestations of hyperkalemia?

Answer 26

peaked t wave, wide qrs, sine-wave morphology (ventricular tachycardia)

Question 27

what are signs and symptoms of hyperkalemia?

Answer 27

cardiac toxicity (ekg changes, conduction defects arrhythmias)
neuromuscular changes
ascending weakness, ileus

Question 28

How do you treat hyperkalemia

Answer 28

insulin, b agonist, bicarbonate, to move into cells

diuretics resins and dialysis to remove from body

Question 29

what are the general causes of hypokalemia?

Answer 29

decreased intake
increased excretion
internal redistr

Question 30

what are specific causes of hypokalemia

Answer 30

GI losses, cutaneous losses, renal losses

insulin excess
catecholamin excess alkalemia, cell proliferation

Question 31

what two broad types of disorders can you group hypokalemia into?

Answer 31

normotensive, hypertensive

Question 32

What can lead to normotensive hypokalemia?

Answer 32

diuretics, prolong vomiting, bartters and gitelmans (all with metabolic alkalosis)

renal tubular acidosis, ureteral diversion (all with metabolic acidosis)

Question 33

What is hyperreninemia due to

Answer 33

renal artery stenosis or renin-secreting tumor

Question 34

what causes primary hyperaldosteronism

Answer 34

conn’s syndome adrenal hyperplasia adrenal tumor

Question 35

What are clinicla manifestations of hypokalemia?

Answer 35

chronic is typically asymptomatic

acute has muscle weakness, ekg changes, nephrogenic diabetes insipidus, htn, ileus