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A. White- Human Physiology > Renal Regulation of Ion Concentrations > Flashcards

Renal Regulation of Ion Concentrations Flashcards

1
Q

You encounter a patient who is experiencing symptoms of cardiac arrest. Would you expect their extracellular potassium levels to be high or low?

A

High

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2
Q

How much of the total body potassium is located in the extracellular fluid?

A

2%

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3
Q

What is the normal intracellular concentration of potassium ions?

A

140 mEq/L

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4
Q

An increase in extracellular potassium stimulates an increase in the secretion of what molecule?

A

aldosterone

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5
Q

Where does reabsorption occur in the nephron?

A

proximal tubule and the ascending limb of Henle

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6
Q

Where does secretion occur in the nephron?

A

late tubule and collecting duct.

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7
Q

How are principle cells stimulated to secrete potassium and aldosterone?

A

They are dependent upon potassium concentration and aldosterone.

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8
Q

Is there an inverse or direct relationship between aldosterone secretion and extracellular potassium secretion?

A

direct

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9
Q

Potassium concentration is indirectly affected by what molecule?

A

aldosterone

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10
Q

If the aldosterone system is blocked, how will potassium regulated be affected?

A

Potassium will not be as regulated; the aldosterone system imparis regulation of potassium concentration.

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11
Q

A high potassium diet is usually correlated with what?

A

A high secretion of potassium.

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12
Q

How does a in increased sodium diet affect potassium excretion?

A

It does not affect potassium excretion.

An increased intake of sodium decreases aldosterone (decreases K+ secretion) and increases distal tubular flow rate (increases K+ secretion). These counteract each other and there is not net change in potassium excretion.

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13
Q

Approximately what percentage of total plasma calcium is in the ionized form?

A

50%.

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14
Q

You encounter a patient who is experiencing acidosis. Do you expect high or low levels of calcium to be bound to the plasma proteins?

A

low

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15
Q

You encounter a patient with alkalosis. Do you expect high or low levels of calcium to be bound to the plasma proteins?

A

high

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16
Q

Almost all of the calcium in the body is stored where?

A

In the bones

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17
Q

What hormone is one of the most important regulators of bone uptake and release of calcium?

A

Parathyroid hormone

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18
Q

Vitamin D is activated by what hormone?

A

Parathyroid hormone

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19
Q

How much of the filtered calcium is reabsorbed, and what region of the nephron absorbs most of it?

A

99%; the proximal tubules absorb the most through paracellular (65%) and transcellular (20%) routes.

20
Q

How is calcium reabsorbed in the proximal tubules?

A

Through paracellular (65%) and transcellular (25%) routes.

21
Q

What region of the loop of henle absorbs calcium?

A

thick ascending limb.

22
Q

How is calcium reabsorbed in the distal tubule?

A

via active transport.

23
Q

What factors regulate tubular calcium reabsorption?

A

increased PTH

Plasma concentration of calcium

metabolic acidosis

24
Q

Reabsorption in the distal tubule is stimulated by what hormone?

A

PTH

25
Q

Calcium excretion is decreased by what factors?

A

Decreased PTH

Plasma concentration of phosophate

Metabolic acidosis

26
Q

When parathryoid hormome is increased, what three regions of the body will subsequently increase calcium reabsorption?

A

intestines, kidneys and bones.

27
Q

What is the phosphate transport maximum for reabsorption?

A

0.1 mM/min.

If it is above this value, excess is secreted.

If it is below this value, all filtered phosphate is reabsorbed in the proximal tubule.

28
Q

What is the relationship between PTH and phosphate?

A

An increase in PTH causes an increase of extracellular phosphate, which is eventually lost in the urine.

29
Q

During a fed state, insulin is released. What is the relationship of insulin and potassium?

A

Insulin stimulates potassium uptake by cells.

30
Q

You encounter a patient who is experiencing Conn’s Syndrome (hyporkalemia). You order a blood test. Do you expect aldosterone levels to be high or low?

A

high

31
Q

You encounter a patient who has Addison’s disease (hyperkalemia). You order a blood test. Do you expect aldosterone levels to be high or low?

A

low

32
Q

What is the function of aldosterone?

A

It increases potassium uptake by cells.

It also stimulates active reabsorption o Na+ by principal cells via Na/K ATPase pump.

33
Q

As extracellular potassium increases, what substance is secreted?

A

aldosterone

34
Q

What is the function of catecholamies?

A

They stimulate potassium uptake by cells.

35
Q

You encounter a patient who has metabolic acidosis. You order a blood test. Do you expect plasma (extracellular) concentrations of potassium to be high or low?

A

high

36
Q

You encounter a patient who has metabolic alkalosis. You order a blood test. Do you expect their plasma (extracellular) levels to be high or low?

A

low

37
Q

You perform a study on rats that have undergone strenous excercise and are experiencing hyperkalemia. What physiological symptoms do you expect the rats to have?

A

cell lysis and increased extracellular fluid osmolarity.

38
Q

What are the major cells found in the late distal tubule and collecting tubules?

A

principal cells.

39
Q

What type of pump is important in controlling K+ secretion?

A

Activity of the Na/K ATPase pump.

40
Q

What three factors control K+ secretion?

A

Activity of the Na/K ATPase pump

Electrochemical gradients

Permeability of luminal membrane.

41
Q

What three factors stimulate K+ secretion?

A

Increased extracellular K+ concentration

Increased aldosterone

Increased tubular flow rate

42
Q

What is the function of intercalated cells?

A

To reabsorb potassium during potassium depletion.

They reabsorb through a H/K ATPase pump.

H+ is secreted into the lumen.

43
Q

In order to excrete high levels of sodium, what must happen to blood pressure?

A

It has to increase.

44
Q

At reduced angiotensin II levels, ____ levels of sodium can be maintained at reduced arterial pressures.

A

normal

45
Q

At what concentration is extracellular potassium maintained?

A

4.2 mEq/L (+/- 0.3 mEq/L)

A. White- Human Physiology (32 decks)

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