Session 5- Regulation of Potassium Flashcards Preview

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Flashcards in Session 5- Regulation of Potassium Deck (15)
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1
Q

normal range of potassium

A

3.5 - 5.5 mmol/l

2
Q

how does membrane potential change with ECF K+

A

if ECF K+ rises the resting membrane potential is decreased

if ECF K+ falls the resting membrane postential is increased

3
Q

hypokalaemia on a ECG

A

slightly prolonged PR interval

slighly peaked P wave

shallow T wave

prominent U wave

ST depression

4
Q

hyperkalaemia on ECG

A

decreased R wave amplitude

wide, flat P wave

prolonged PR interval

widened QRS

decreased ST segement

Tall peaked T wave

5
Q

water distribution in body

A

60% is water

of that 2/3 intra 1/3 extra

of 1/3 extra 25% plasma 75% interstitual fluid

6
Q

where is the majority of K reabsorbed

A

67% PCT
Thick ascending limb through NKCC
DCT- ROMK

7
Q

where is k reabsorbed and secreted

A

collecting duct -ROMK

8
Q

how does teh kidney alter the secretion of K in alkalosis

A

Beta intercalated cells in PCT

reabsorbs H+
secrete K+ and HCO3-

9
Q

How does the kidney alter the absorbption of K+ in acidosis

A

Alpha intercalated cells in PCT

secrete H+
reabsorb K+ and HCO3-

10
Q

Clinical features of hyperkalaemia

A

muscle weakness

cardiac arrythmias

11
Q

what can cause hyperkalemia

A

lack of excretion
release from cells
excess administration

12
Q

how do we treat hyperkalaemia

A

calcium gluconate - Ca2+ stabalises the myocardium preventing arrythmias

insulin-drives K+ into cells to lower plasma conc. Given with glucose to avoid hypoglycaemia

calcium resonium- removes K+ by increasing excretion from the bowels

13
Q

what causes hypokalaemia

A

reduced dietary intake
increased entry into cells
increase GI losses
increased urine loss

14
Q

clinical effects of hypokalaemia

A

muscle wekaness, cramps and tetany

vasoconstriction and cardiac arrythmias

impaired ADH action causing thirst, polyuria and no conc of urine

metabolic alkalosis due to increas ein intracellualr H+ conc

15
Q

how do we treat hypokalaemia

A

potassium replacement

  • oral
  • iv
  • potassium sparing diuretics