Renal Role in Normal Potassium Homeostasis Flashcards
extracellular K+ is maintained at what range
3.5-5
why is most of the body’s K+ intracellular
- the Na/K ATPase
what is the reservoir for excess K+ ingested during a meal
- skeletal muscle
what hormones stimulate uptake of K+ into skeletal muscle cells
how?
what is the signal
- aldosterone
- epinephrine
- insulin
- increase Na+/K+ ATPase activity
- increases in plasma K+
if you have acidosis, what is your potassium level
why?
- high
- hyperkalemic
- H+ taken up by cells in exchange for K+
if you have alkalosis, what is your potassium level?
why?
- low
- hypokalemic
- H+ exits cells in exchange for K+
process of proximal tubule reabsorption of K+
- reabsorb Na and AA, glucose
- leaves tubule lumen hypoosmotic
- water flows into cell through aquaporins or paracellular transport
- drags K+ with it
what is necessary in order to drive the NKCC transporter
- tubular K+ secreted by ROMK
what keeps intracellular K+ high and Na+ low
- Na/K ATPase
role of the principal cell in regard to potassium
through what channel
respond to
- secrete potassium
- ROMK
- aldosterone
role of the alpha intercalated cell in regard to potassium
through what channel
- reabsorb potassium
- H/K ATPase
what stimulates K+ secretion
- elevated plasma K
- aldosterone
- dietary intake of K
- increased tubular flow rates
- increased tubular negativity
how does elevated plasma K stimulates K+ secretion
- stimulates Na+/K+ ATPase
how does aldosterone stimulate K+ secretion
- stimulates ENac
- Na+/K+ activity
- increases number of ROMK channels
how does dietary intake of K+ stimulate K secretion
- kidney increases ROMK channels
