Potassium Balance Flashcards
Potassium is the major ________ ion. Concentration?
intracellular
150mmol/L
effect of extracellular K+?
effect on excitable membranes of nerve and muscle, depolarisation, heart arrythmias
K+ uptake from plasma due to what hormones?
insulin
aldosterone
adrenaline
immediate response to dietary K+
insulin stimulates the activity of the sodium proton exchanger > ^intracellular Na+ > activates sodium potassium ATPase > ^K+ uptake.
K+ in the nephron
67% reabsorbed in PCT
20% reabsorbed in loop of Henle
depending of plasma levels can be reabsorbed in DCT/CD also
K+ secretion/excretion is stimulated by?
increased plasma [K+]
increased aldosterone
increased tubular flow rate
increased plasma pH
increased plasma [K+] leads to increased K+ secretion by?
increased activity of the sodium potassium ATPase and reduce return of potassium into the plasma
how does tubular flow regulate potassium?
activating cilia > activate PDK1 > increases Ca++ in the cell > stimulates the opening of potassium channels on the apical membrane
causes of hypokalaemia
inadequate dietary intake diuretics surreptitious vomiting diarrhoea genetics
genetic causes of hypokalaemia
Gitelman’s syndrome mutation in the Na/Cl transporter in the distal nephron
causes of hyperkalaemia
K+ sparing diuretics ACE inhibitors elderly severe diabetes kidney disease
symptoms of hypokalaemia
Weakness and fatigue Muscle cramps and pain Worsening diabetes control or polyuria Palpitations Psychological symptoms
symptoms of hyperkalaemia
Muscle weakness Numbness and tingling Nausea and vomiting Irregular heartbeat Shortness of breath
