l11

Question 1

what is the total body content potassium

Answer 1

50 meq/kg of body weight or 3500 meq for 70 kg person

Question 2

intracellular concentration potassium

Answer 2

150 mEq/L (98%)

Question 3

how much potassium is in muscle cells, rbc, liver, and bones?

Answer 3

muscle- 2600 mEq

RBC, liver, bones- 300 mEq

Question 4

how much potassium in ECF

Answer 4

65 mEq (@% body weight)

Question 5

normal range plasma K+

Answer 5

3.5-5 mEq/l

Question 6

value of ecf for hyperkalemia and hypokalemia

Answer 6

hyperkalemia- above 5 meq/L

hypokalemia- below 3.5 mEq/L

Question 7

what 2 hormones are upregulated after a meal and help Na-K ATPase, and which is the most important

Answer 7

epinephrine and insulin. insulin is the most important

Question 8

what is th eplasma K in patients with B blocker (propanolol)

Answer 8

elevated longer because K not uptoo

Question 9

one way to treat hyperkalemia with glucose

Answer 9

give glucose to release insulin, which will regulate K hyperkalemia by increasing Na-K ATPase

Question 10

A drop in 0.1 pH results in how much change in K

Answer 10

increase 0.6 mEq/L plasma K results

Question 11

acidosis causes what change in plasma k

Answer 11

Variable
acidosis causes hyperkalemia- inhibits K/H exchanger and inhibition of Na-K ATPase on basso lateral membrane on distal nephron
-inhibition of Na K ATPase in pt cells by low pH decreases na/water reabsorption, increases tubular flow, enhancing k secretion
-chronic acidosis-ecf can decreases and inorganic acids can rise and aldosterone is secreted

Question 12

metabolic or respiratory acidosis causes K changes

Answer 12

metabolic acidosis (HCL, NaHCO3) causes shift in plasma K, but respiratory or organic acids (lactic acids, ketones) do not cause a shift in K

Question 13

how does increases in osmolality (hyperglycemia) change K

Answer 13

hyperosmolality- h2o moves out first to ecf then [K] inside cell increase, so K moves to ecf- results in hyperkalemia

Question 14

how much K excreted per ady

Answer 14

90 mEq

Question 15

how is K reabsorbed in kidney

Answer 15

mostly in proximal tubule (80%) and TAL (10%); by intercellular diffusion through junctions and positive potential favors paracellular reabsorption; in TAL by NaK2CL transporter

Question 16

where does K secretion and reabsorption take place

Answer 16

mostly secretion by principal cell distal tubule (uptake by basolateral Na-K ATPase, higher conductance of apical channels so K diffuses into lumen); reabsorption by intercalated a type MCD (H secreted out, K in)

Question 17

what 3 factors control K secretion

Answer 17

1) Na K ATPase
2) electrochemical gradient for K movement across apical membrane
3) apical permeability to K

Question 18

how does hyperkalemia regulate K secretion

Answer 18

hyperkalemia increases NaK ATPase on basolateral membrane and increases permeability of K on apical membrane- both in distal nephron; independent of aldosterone because in adrenalectomized animals see same results

Question 19

how does aldosterone (and nagiotensin 2) regulate K secretion

Answer 19

upregulates Na K atpase, k and Na channels in principal cells in distal nephrons. also increased Na into cell depolarizes lumenal membrane and K secreted

Question 20

how does adrenal tumor or addisons disease effct plasma k

Answer 20

adrenal tumor- hypokalemia becuase too much aldosterone leads to K secretion
-aldosterone deficiency in addison’s disease- hyperkalemia because not secreting K

Question 21

ANP and plasma K

Answer 21

ANP inhibits aldosterne, so K not secreted

Question 22

what 3 factors cause high flow to increase K secretion

Answer 22

1- high flow rate deforms mechano-sensitive channels that causes opening of Ca-K channels
2- maintains high chemical gradient by diluting and washing away secreted K
3- more Na delivered to distal nephron, so more Na reabsorbed and K secreted and depolarizes lumenal membrane

Question 23

what is the effect of diurectics on plasma K

Answer 23

increases flow rate, which increases K secretion. so K needs to be administered to prevent hypokalemia. or use spironolactones as competitive inhibitors of aldosterone as a diurectic to inhibit K secretion

Question 24

what is the effect of acidosis on plasma K

Answer 24

variable-
inhibits Na-K ATPase at distal nephrone so K secretion reduced
-also inhibits Na-K ATPase at proximal tube and decreases salt and water reabsorption, which increases flow, which would increase K secretion
-chronic metabolic acidosis, ECF volume decrease stimulating RAA system which would increase K secreation

Question 25

Hyper polarization of principal cell membrane would cause what change to K secretion

Answer 25

Hyperpolarization would decrease driving force for K secretion

Question 26

Deformation of principal cells does what to k secretion

Answer 26

Deformation leads to influx of Ca which activate K channel

Question 27

How does ADH effect U/P for inulin?

Answer 27

It increases u/p for inulin because more water reabsorbed

Question 28

Loop diuretic and tubular osmolar clearance

Answer 28

Loop diuretic inhibits sodium and water reabsorption, so there would be a higher osmolar clearance

Question 29

Loss of blood volume and free water clearance

Answer 29

For a big loss in blood volume, baroreceptor sand cardiopulmonary receptors stop firing, ADH activated, increases urine concentration and therefore negative free water clearance

Question 30

Diabetic ketoqcidosis and H and titratable acid concentration

Answer 30

Diabetic ketoqcidosis causes increase formation of HCO3- and increased secretion of H and therefore increases TA