Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology > Renal regulation of K and Ca > Flashcards

Renal regulation of K and Ca Flashcards

1
Q

The vast majority of body potassium is located

A

In the cells

- is the most important intracellular ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Potassium output

A
  • urine: 92 mEq/d
  • feces: 8 mEq/d
  • total: 100 mEq/d
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Partitioning of Na and K across cell membrane allows for

A

Polarity differences that are critical for excitable membranes and the development of action potentials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Intracellular dehydration

A

Due to loss or lack of intake leading to long term potassium wasting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How does urinary excretion of potassium range from 1 - over 100% of what was filtered at the glomerulus?

A

Tubules can reabsorb almost all of what was filtered to actually secreting extra potassium into the tubule on top of what was filtered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Plasma potassium only represents _____

A

A small fraction of whole body potassium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How to assess overall body potassium status

A

Measure renal potassium fractional excretion

- asses proportion of potassium filtered across the glomerulus compared to that contained in the urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Causes of extracellular K moving into the cell

A
  • increases K intake
  • insulin
  • aldosterone
  • beta-adrenergic
  • alkalosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Causes of intracellular K moving out of the cell

A
  • cell lysis
  • strenuous exercise
  • acidosis
  • beta blockade
  • HYPP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Insulin

A

Insulin surge after eating moves excess K just ingested from the ECF into the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

____ and ____ tend to push K into cells

A

Insulin; alkalosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Giving IV bicarb causes H ions to move out of the cells to maintain normal pH, and K moves _____ to maintain an electroneutral exchange of ions

A

Into cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Cellular acidosis

A

Results in K moving out of the cell to maintain electroneutrality within the cell and reduce K uptake into the cell by decreasing the efficiency of the Na K ATPase pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Patients that are inappetent and suffering from GI electrolyte losses are _____

A

In a negative potassium balance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The ______ is responsible for long term sustainable control of potassium

A

Kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Potassium excretion is determined by the sum of 3 renal processes:

A
  • rate of filtration
  • tubular K reabsorption/secretion
  • tubular flow rate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Acute renal failure

A

Results in a decrease in GFR and can cause serious K accumulation and hyperkalemia due to a high potassium diet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the primary cell involved in potassium excretion?

A

Principal cells of the late distal and collecting tubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the limiting factor of the Na K ATPase pump?

A

Electrolyte availability, NOT energy!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Aldosterone secretion is increased by

A

Increased serum potassium

  • independent of angiotensin 2
  • causes increased secretion of K into the distal tubule lumen by the principle cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where is the primary site of aldosterone?

A

On the principle cells of the cortical collecting tubule

22
Q

Aldosterone feedback loop

A

Increased K intake –> increased plasma K concentration —> increased aldosterone (+) –> increased K secretion cortical collecting tubules –> increased K excretion

23
Q

What happens to K in the absence of aldosterone secretion?

A

Renal secretion of K is impaired, leading to ECF potassium concentration to rise to high levels

24
Q

What happens to K with excess aldosterone secretion?

A

Potassium secretion becomes greatly increased, causing potassium loss by the kidneys = hypokalemia

25
Q

Does decreased aldosterone secretion due to a Na rich diet lead to K retention?

A

No, effects are counterbalanced by increased flow rate, which moves any filtered K downstream fast enough that there is a minimal build up of K within the lumen

26
Q

An increase in distal tubular flow rate (due to volume expansion, high Na intake, etc) stimulates potassium _____

A

Secretion

27
Q

A decrease in distal tubular flow rate (caused by sodium depletion) leads to _______

A

Reduced K secretion

28
Q

The effect of tubular flow rate on K secretion is the distal and collecting tubules is strongly influenced by _______

A

Potassium intake

29
Q

The principle cell apical membrane contains ________

A

Unregulated K channels

30
Q

Intercalated type A cells are able to actively pump _____ out against a high concentration gradient

A

H ions

- function to reabsorb K

31
Q

Acidosis results in extra H in the cells, forcing ______

A

K to diffuse out

  • to maintain electroneutrality
  • chronic acidosis results in potassium wasting and whole body potassium depeletion
32
Q

Intercalated type B cells

A

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
Q

_____ of calcium is in bone

A

99%

34
Q

Ionized divalent cation

A

Form of free circulating calcium

35
Q

Calcium is loosely bound to ____

A

Albumin due to albumin’s negative charge

- bound for is not biologically active

36
Q

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

A

Decreases; increases

37
Q

Number of receptors is controlled by ____

A

PTH

38
Q

Increase in serum Ca =

A

Decrease in PTH

39
Q

Decrease in serum Ca =

A

Increase in PTH

40
Q

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

A

Phosphotidyl inositides

  • bind Ca avidly
  • rapid turnover times
  • number of receptors determined by PTH
41
Q

PTH secretion is determined by state of calcium ___ or ____

A

Repletion or depletion

42
Q

What happens when excess Ca enters the cell?

A

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

43
Q

What is another location of PTH responsive Ca absorption?

A

Thick ascending loop of Henle

- paracellular movement of cations predominates in this portion

44
Q

Distal convoluted tubule absorbs ____ through the transcellular pathway

A

5-10% of calcium

45
Q

Does Ca absorption occur in the medullary collecting ducts?

A

No

46
Q

The kidney is critical in the activation of ______

A

Vitamin D

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

47
Q

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

A

Not activated and is excreted

48
Q

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

A

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

49
Q

Phosphates

A

Most diets contain phosphates in excess and reabsorption is fairly unregulated

50
Q

Phosphates - short term

A

Transport max

  • when phosphate < transport max, most is absorbed
  • when phosphate > transport max, most is excreted
51
Q

Phosphates - long term

A

Transport max can vary depending on PTH

- increase PTH decreases phosphate transport max, leads to decrease in phosphate reabsorption

Physiology (33 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions