Muster - K and Ca Regulation

Question 1

what do you give to stabilize cardiac function in someone who is hyperkalemic

Answer 1

Calcium

Question 2

do you have cells that secrete sodium?

Answer 2

no

Question 3

what is 100% absorbed in the proximal tubule

Answer 3

glucose

Question 4

function of the BK channels

Answer 4

extra potassium channels for when you really need to get K out of the cell

Question 5

what common hormone blocks the ROMK channel and why does it?

Answer 5

angiotensin II

is so that when the kidney tries to retain sodium by upregulating the Na/K antiporter, you don’t loose a bunch of that intracellular potassium to the lumen (urine) of the kidney

Question 6

in what instance would you see a rise in aldosterone without a rise in angiotensin II

Answer 6

hyperkalemia

Question 7

why does someone become hypokalemic if you put them on a loop diuretic

Answer 7

NKCC is blocked in proximal tubule

more Na in the distal tubule, so Na flows down its concentration gradient through the ENac channel

to balance this, K is secreted out of the ROMK channels

Question 8

where are the principle and intercalated cells of the kidney

Answer 8

in the distal colvoluted tubule

they have the Na/K antiporter, ROMK, ENac and BK channels

Question 9

what effect does Mg have on the principle cells of the kidney

Answer 9

they block the ROMK channels from the inside, making it hard to retain potassium if you are low on magnesium

Question 10

most of our regulation of K is through secretion or absorption?

Answer 10

secretion

Question 11

what does the alpha intercalated cell use as an antiporter in order for it to kick out hydrogen ions

Answer 11

potassium

Question 12

Why can you get a metabolic alkylosis if you are hypokalimic

Answer 12

because the way the alpha intercalated cell takes back up K from the lumen is by switching it with H+

Question 13

calcium’s relationship to the parathyroid

Answer 13

parathyroid glands have calcium sensors on them. When ionized clacium binds, it inhibits the production of PTH

Question 14

effects of PTH

Answer 14

1. works directly on the bone by stimulating immediate release of calcium and phospherous
2. it tells the kidney to retain Ca
3. increases and stimulates the production of 125 dihydroxy vitamin D (1st position - the first place the Vit D is hydroxylated by the liver. 25th position - the second place it is hydroxylated by the kidney)

(vitamin D makes the gut absorb more calcium)

4. decreases renal phosphorus absorption (get decreased serum phospherous)

Question 15

Explain what happens to you ion levels in primary hyperparathyroidism

Answer 15

increased Ca - resorbed from bone

increased Ca - vit D in gut

decreased or normal serum PO4 - it is resorbed from the bone but the kidneys don’t resorb it

Question 16

what are you thinking if you see evidence of primary hyperparathyroidism but the PTH is low?

Answer 16

some cancers produce PTH mimicking “PTH related peptide” “PTHrp”

granulomatous disease producing excess vitamin D

Question 17

what is the “only other time” that your body is making activated vitamin D if the kidneys aren’t doing it?

Answer 17

if you have a granulomatous disease i.e. wegener’s, sarcoidosis