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Flashcards in Renal regulation of K and Ca Deck (51)
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31

Acidosis results in extra H in the cells, forcing ______

K to diffuse out
- to maintain electroneutrality
- chronic acidosis results in potassium wasting and whole body potassium depeletion

32

Intercalated type B cells

Have the H K ATPase counter exchange pumps and H ATPase pumps in the basolateral cell membrane
- primarily responsible for maintaining pH by getting rid of excess bicarb during alkalosis
- function to secrete K

33

_____ of calcium is in bone

99%

34

Ionized divalent cation

Form of free circulating calcium

35

Calcium is loosely bound to ____

Albumin due to albumin's negative charge
- bound for is not biologically active

36

Acidosis ____ Ca binding, while alkalosis ___ Ca-albumin binding

Decreases; increases

37

Number of receptors is controlled by ____

PTH

38

Increase in serum Ca =

Decrease in PTH

39

Decrease in serum Ca =

Increase in PTH

40

What is the name of the Ca carrier molecule located on the apical membrane of the proximal tubules?

Phosphotidyl inositides
- bind Ca avidly
- rapid turnover times
- number of receptors determined by PTH

41

PTH secretion is determined by state of calcium ___ or ____

Repletion or depletion

42

What happens when excess Ca enters the cell?

Activates proteases that can result in significant cell damage and cell death

43

What is another location of PTH responsive Ca absorption?

Thick ascending loop of Henle
- paracellular movement of cations predominates in this portion

44

Distal convoluted tubule absorbs ____ through the transcellular pathway

5-10% of calcium

45

Does Ca absorption occur in the medullary collecting ducts?

No

46

The kidney is critical in the activation of ______

Vitamin D
- need UV light if active VD is not in the diet

47

If you do not need more Ca, then vitamin D is ___

Not activated and is excreted

48

If you do need more Ca, then vitamin D is ____

Converted to active form and will activate Ca absorption in the GIT and Ca mobilizaiton out of the bone stores

49

Phosphates

Most diets contain phosphates in excess and reabsorption is fairly unregulated

50

Phosphates - short term

Transport max
- when phosphate < transport max, most is absorbed
- when phosphate > transport max, most is excreted

51

Phosphates - long term

Transport max can vary depending on PTH
- increase PTH decreases phosphate transport max, leads to decrease in phosphate reabsorption