18 K+ and more!:)

Question 1

What is the intracellular concentration of K+?

Answer 1

140mM

Question 2

What is the extracellular concentration of K+/

Answer 2

4mM

Question 3

How can any adverse affects of increased extracellular K+ be avoided?

Answer 3

buffering by uptake into cells

Question 4

What 6 things might cause hyperkalaemia?

Answer 4

CKD 5
crush injuries
blood transfusion
cytotoxic drugs
insulin deficiency
over use of K+ sparing diuretics

Question 5

Why might blood transfusion cause hyperkalaemia?

Answer 5

red cells leak some K+ into the plasma during storage

Question 6

Why might giving glucose treat hyperkalaemia?

Answer 6

stimulates insulin release

insulin stimulates Na+/K+ ATPase
cells uptake K+

Question 7

Name 3 causes of hypokalaemia

Answer 7

diarrhoea
furosemide (along with most diuretics)
insulin overdose

Question 8

what might you do if someone is have significant furosemide-induced hypokalaemia?

Answer 8

decrease the concentration of furosemide and increase concentration of K+ sparing diuretic

Question 9

name a K+ sparing diuretic

Answer 9

sprinolactone

Question 10

What is the main dangerous consequence of hypo or hyperkalaemia?

Answer 10

dysrhythmia

Question 11

How might you treat hypokalaemia?

Answer 11

give IV K+ if acute

give orally if chronic

Question 12

How is K+ exchanged in the TAL?

Answer 12

through NKCC cotransporter

much of the K+ cycles back into the filtrate here though

Question 13

How is K+ exchanged in the DCT and CD?

Answer 13

apical membrane K+ channel (ROMK) (aldosterone)

A Ca2+ activatead K+ channel (flow rate dependent)

Question 14

What is aldosterone secretion sensitive to?

Answer 14

AngII

K+

Question 15

What is the main hormone for regulating bodily K+?

Answer 15

aldosterone

Question 16

What proportion of total Ca2+ is filtered by the glomerulus?

Answer 16

10% total

20% free

Question 17

what happens to filtered calcium in the PCT?

Answer 17

moves transcellularly

proportional to H2O movement

Question 18

What happens to filtered calcium in the TAL?

Answer 18

absorbed

driven by + potential in the lumen of the TAL

Question 19

Why is there a positive potential in the TAL lumen?

Answer 19

MKCC is electrically neutral
apical K+ recycling makes the filtrate +

this drives the reabsorption of Ca2+

Question 20

How does ascending to high altitudes affect red cell production?

Answer 20

it increases it

Question 21

where is EPO made?

Answer 21

renal mesangial cells

Question 22

What is another name for mesangial cells?

Answer 22

peritubular fibroblasts

Question 23

What stimulates transcription of EPO?

Answer 23

hypoxia-inducible factors (HIF-2)

Question 24

What is HIF-alpha degradation enhanced by?

Answer 24

Fe2+

Question 25

How does iron affect EPO?

Answer 25

low iron causes EPO production

Question 26

How is EPO regulated?

Answer 26

EPOR binds and internalises EPO

Question 27

how does renal failure lead to anaemia?

what is the exception to this?

Answer 27

falls in EPO production

polycystic kidney disease

Question 28

How does polycystic kidney disease not cause anaemia?

Answer 28

sufficient renal parenchyma to prevent loss of EPO production

Question 29

What EPO analogue is used clinically?

Answer 29

Darbepoietin alpha

Question 30

Can EPO be found in urine

Answer 30

yes, a little bit as it is 34kDa

Question 31

What is the other name for vitamin D?

Answer 31

cholecalciferol

Question 32

How is vitamin D metabolised?

Answer 32

converted to 25-hydroxycholecalciferol in the liver

converted to 1,25-hydroxycholecalciferol by the kidney

Question 33

What are the actions of 1,25-VitD?

Answer 33

increase Ca2+ and phosphate absorption in the ileum

decrease Ca2+ and phosphate excretion