Renal - Physiology Flashcards Preview

USMLE (S1) Renal > Renal - Physiology > Flashcards

Flashcards in Renal - Physiology Deck (187)
Loading flashcards...
1
Q

Identify (A), (B), and (C), which are actively absorbed into the thick tubule cell, and (D) and (E), which are passively reabsorbed.

A

(A) sodium; (B) potassium; (C) two chloride ions; (D) magnesium; (E) calcium

2
Q

Elevated parathyroid hormone increases exchange of (A) and (C) between cell and blood. How does this affect uptake of (C) from the lumen?

A

(A) sodium; (C) calcium; increased exchange reduces intracellular calcium and allows more luminal calcium to be reabsorbed

3
Q

Hydrochlorothiazide inhibits the active reabsorption of (A) and (B) from the lumen. How does this affect tonicity of the urine?

A

The absorption of (A) sodium and (B) chloride helps to make the urine hypotonic; inhibition of this process makes the urine more hypertonic

4
Q

In Gitelman syndrome, early distal convoluted tubules do not actively reabsorb (A) and (B). How does this affect reabsorption of (C)?

A

More reabsorption; less intracellular Na+ from less pumping increases (A/C) Na+/Ca2+ exchanger activity, increasing (C) Ca2+ reabsorption

5
Q

Nonwater mass comprises _____% of total body weight (in kilograms), while total body water (in liters) makes up _____% of total body weight.

A

40% nonwater mass; 60% total body water

6
Q

What fraction of total body water is extracellular vs intracellular fluid?

A

One third extracellular fluid, two thirds intracellular fluid

7
Q

What fraction of the extracellular fluid is plasma volume vs interstitial volume?

A

One fourth plasma volume, three fourths interstitial volume

8
Q

What substance is used to measure plasma volume?

A

Radiolabeled albumin

9
Q

What substance is used to measure extracellular volume?

A

Inulin

10
Q

What is the 60-40-20 rule of body weight?

A

60% of total body weight is made up of total body water, 40% is made up of intracellular fluid, and 20% is made up of extracellular fluid

11
Q

What is the normal value for plasma osmolarity?

A

290 mOsm

12
Q

Extracellular fluid consists of _____ (high/low) sodium chloride and _____ (high/low) potassium, whereas intracellular fluid consists of _____ (high/low) sodium chloride and _____ (high/low) potassium.

A

High; low; low; high (remember: HIKIN': HIgh K INtracellular)

13
Q

What are the two characteristics on which the glomerular barrier bases plasma filtration?

A

Size and net charge of plasma molecules

14
Q

The fenestrated capillary endothelium of the glomerular filtration barrier is responsible for the filtration of plasma by what characteristic, size or charge?

A

Size

15
Q

The fused basement membrane of the glomerulus containing heparan sulfate is responsible for the filtration of plasma molecules by which characteristic, size or charge?

A

Net charge

16
Q

What kind of charge does heparan sulfate have?

A

Negative; as a result, negatively charged proteins are kept in plasma

17
Q

The epithelial layer of the glomerular filtration barrier is formed by which cells?

A

Podocyte foot processes

18
Q

What are the three components of the glomerular filtration barrier?

A

Fenestrated capillary endothelium (size barrier), fused basement membrane with heparan sulfate (negative charge barrier), and epithelial layer that consists of podocyte foot processes

19
Q

Albuminuria, hypoproteinemia, generalized edema, and hyperlipidemia are hallmarks of what syndrome?

A

Nephrotic syndrome; resulting from loss of the charge barrier in the glomeruli

20
Q

What is the formula for calculating the clearance of substance x, the volume of plasma from which the substance is cleared completely per unit of time?

A

Renal clearance of x = the urine concentration of x times the urine flow rate divided by the plasma concentration of x (Cx = Ux × V/Px)

21
Q

If renal clearance is less than the glomerular filtration rate of substance x, then there is net tubular _____ (reabsorption/secretion) of x.

A

Reabsorption

22
Q

If renal clearance is greater than the glomerular filtration rate of substance x, then there is a net tubular _____ (reabsorption/secretion) of x.

A

Secretion

23
Q

Why is para-aminohippurate used to estimate renal plasma flow?

A

Para-aminohippurate is actively secreted from the proximal tubule into the urine; the concentration of para-aminohippurate in the renal vein is zero

24
Q

The clearance of what substance is used to estimate renal plasma flow?

A

Para-aminohippurate

25
Q

What is the formula for estimating the effective renal plasma flow using para-aminohippuric acid?

A

Effective renal plasma flow = urine concentration of para-aminohippuric acid times the urine flow rate divided by the plasma concentration of para-aminohippuric acid (UPAH × V/PPAH)

26
Q

What is the formula for estimating renal blood flow if renal plasma flow is known?

A

Renal blood flow = renal plasma flow divided by (1 - the hematocrit), or RBF = RPF/(1 - Hct); in a normal individual, renal blood flow will be approximately double the renal plasma flow

27
Q

Effective renal plasma flow _____ (over-/under-) estimates true renal plasma flow by approximately _____%.

A

Under; 10

it is an underestimate because 10% of renal blood flow perfuses the kidney parenchyma rather than being filtered through the glomerulus

28
Q

How is the filtration fraction for a molecule determined?

A

By determining the ratio of the glomerular filtration rate to renal plasma flow

29
Q

What are the effects of prostaglandins on the glomerulus?

A

Prostaglandins cause dilation of the afferent arteriole and an increased glomerular filtration rate

30
Q

What are the effects of angiotensin II on the glomerulus?

A

Angiotensin II causes constriction of the efferent arteriole and increased glomerular filtration rate

31
Q

What type of drug blocks the effect of prostaglandins on the afferent arteriole?

A

Nonsteroidal antiinflammatory drugs

32
Q

What type of drug blocks the effect of angiotensin II on the efferent arteriole?

A

Angiotensin-converting enzyme inhibitors

33
Q

Prostaglandins cause a(n) _____ (decrease/increase) in renal plasma flow, a(n) _____ (decrease/increase) in glomerular filtration rate, and a _____ (constant/decreased/increased) filtration fraction.

A

Increase; increase; constant

34
Q

In terms of filtration in the glomerulus, the filtered load is equal to the glomerular filtration rate multiplied by what?

A

The plasma concentration

35
Q

Angiotensin II causes a(n) _____ (decrease/increase) in renal plasma flow, a(n) _____ (decrease/increase) in glomerular filtration rate, and a _____ (constant/decreased/increased) filtration fraction.

A

Decrease; increase; increased

36
Q

What is the path of blood flow leading to the afferent arteriole?

A

Renal artery to interlobar artery to interlobular artery to afferent arteriole

37
Q

What is the path of vasculature coming from the efferent arteriole?

A

Efferent arteriole to vasa recta to interlobular vein to interlobar vein to renal vein

38
Q

Constriction of the afferent arteriole causes _____ (decrease/increase/no change) in renal plasma flow and _____ (decrease/increase/no change) in glomerular filtration rate, which in turn results in _____ (decrease/increase/no change) in the filtration fraction.

A

Decrease; decrease; no change

39
Q

Constriction of the efferent arteriole causes _____ (decrease/increase/no change) in renal plasma flow and _____ (decrease/increase/no change) in glomerular filtration rate, which in turn results in _____ (decrease/increase/no change) in the filtration fraction.

A

Decrease; increase; increase

40
Q

Increased plasma protein concentration causes _____ (decrease/increase/no change) in renal plasma flow and _____ (decrease/increase/no change) in glomerular filtration rate, which in turn results in _____ (decrease/increase/no change) in the filtration fraction.

A

No change; decrease; decrease

41
Q

Decreased plasma protein concentration causes _____ (decrease/increase/no change) in renal plasma flow and _____ (decrease/increase/no change) in glomerular filtration rate, which in turn results in _____ (decrease/increase/no change) in the filtration fraction.

A

No change; increase; increase

42
Q

Constriction of the ureter causes _____ (decrease/increase/no change) in renal plasma flow and _____ (decrease/increase/no change) in glomerular filtration rate, which in turn results in _____ (decrease/increase/no change) in the filtration fraction.

A

No change; decrease; decrease

43
Q

How is free water clearance calculated?

A

Free water clearance = urine flow rate minus the osmolar clearance (V - Cosm)

44
Q

As part of the free water clearance calculation, how is the total clearance of osmoles calculated?

A

Osmolar clearance = urine osmolarity times the urine flow rate divided by plasma osmolarity (Cosm = Uosm V/Posm)

45
Q

What is free water clearance?

A

A measure of the kidney's ability to dilute urine

46
Q

In the presence of antidiuretic hormone, free water clearance is _____ (greater than/less than/equal to) zero.

A

Less than

(water is retained)

47
Q

In the absence of antidiuretic hormone, free water clearance is _____ (greater than/less than/equal to) zero.

A

Greater than

the body has net loss of water relative to osmoles

48
Q

What is the free water clearance equal to in isotonic urine?

A

Zero

isotonic urine is seen with use of loop diuretics

49
Q

What is the formula for filtered load?

A

Filtered load = glomerular filtration rate × Px; where Px is the plasma concentration of x

50
Q

What is the formula for excretion rate?

A

Excretion rate = V × Ux; where V is the urine flow rate and Ux is the urine concentration of x

51
Q

What is the formula for the amount of a substance reabsorbed in the kidneys?

A

Reabsorption = filtered - excreted

52
Q

What is the formula for the amount of a substance secreted by the kidneys?

A

Secretion = excreted - filtered

53
Q

In the nephron, glucose at normal plasma concentrations is reabsorbed in which structure? By which transporter?

A

Glucose is reabsorbed in the proximal tubule by sodium/glucose cotransport

54
Q

At normal plasma glucose concentrations, how does the proximal tubule handle glucose in the urine?

A

Glucose is completely reabsorbed from the urine

55
Q

When plasma glucose levels exceed 200 mg/dL, what finding may result on urinalysis?

A

Glucosuria; due to inability of the glucose reabsorption mechanism of the proximal tubule to deal with the filtered load of urine glucose

56
Q

Glucosuria is an important clinical clue to what condition?

A

Diabetes mellitus

57
Q

At what concentration of plasma glucose is the transport mechanism of the proximal tubule completely saturated?

A

350 mg/dL

58
Q

How and where are amino acids reabsorbed in the kidney?

A

Amino acids are filtered and then reabsorbed from the urine at the level of the proximal tubule by three distinct sodium-dependent transporters with competitive inhibition within each group

59
Q

What is Hartnup's disease?

A

Deficiency of neutral amino acid (tryptophan) transporter, resulting in pellagra due to niacin deficiency

60
Q

What substance is secreted into the lumen of the early proximal convoluted tubule of the kidney nephron and acts as a buffer for hydrogen ions?

A

Ammonia

61
Q

In the thin descending loop of Henle, water is passively reabsorbed, because the tonicity of the medulla is _____.

A

Hypertonic

62
Q

The thin descending loop of Henle in a kidney nephron is permeable to _____ (sodium/water) but not to _____ (sodium/water).

A

Water; sodium

63
Q

Does the thin descending loop of Henle reabsorb water passively or actively?

A

Passively

64
Q

Which three ions are actively reabsorbed in the thick ascending loop of Henle of a kidney nephron?

A

Sodium, potassium, and chloride

65
Q

In the thick ascending loop of Henle of a kidney nephron, which two ions are indirectly reabsorbed as a result of the active reabsorption of sodium, potassium, and chloride?

A

Magnesium and calcium

66
Q

The thin descending loop of Henle is _____ (impermeable/permeable) to water, whereas the thick ascending loop of Henle is _____ (impermeable/permeable) to water.

A

Permeable; impermeable

67
Q

What two ions are actively reabsorbed in the early distal convoluted tubule of a kidney nephron?

A

Sodium and chloride

68
Q

Which hormone controls the reabsorption of calcium in the early distal convoluted tubule of a kidney nephron?

A

Parathyroid hormone

69
Q

In the collecting tubule of a kidney nephron, which ion is reabsorbed in exchange for secreting potassium or hydrogen ion?

A

Sodium

70
Q

Which segment of the kidney nephron does the hormone aldosterone act on?

A

The collecting tubules

71
Q

Which segment of the kidney nephron does the hormone antidiuretic hormone (vasopressin) act on?

A

The collecting tubules

72
Q

Sodium/potassium exchange and sodium/hydrogen exchange in the collecting tubule of a kidney nephron is regulated by which hormone?

A

Aldosterone

73
Q

The reabsorption of water in the collecting tubule of a kidney nephron is regulated by which hormone?

A

Antidiuretic hormone (vasopressin)

74
Q

What type of cell in the collecting tubule of a kidney nephron is responsible for sodium/potassium exchange and the reabsorption of water?

A

The principal cell

75
Q

On what type of cell in the collecting tubule of a kidney nephron is the vasopressin receptor of the V2 type located?

A

The principal cell

76
Q

Is the reabsorption in the early proximal tubule hypertonic, isotonic, or hypotonic?

A

Isotonic

77
Q

Does the thin descending loop of Henle make the urine in the tubule hypertonic, isotonic, or hypotonic?

A

Hypertonic

78
Q

Is the thick ascending limb of the loop of Henle a concentrating or a diluting segment?

A

Diluting

79
Q

Does the thick ascending limb of the loop of Henle make the urine hypotonic, isotonic, or hypertonic?

A

Hypotonic

80
Q

Is the early distal convoluted tubule a concentrating or a diluting segment?

A

Diluting

81
Q

Does the early distal convoluted tubule make the urine hypotonic, isotonic, or hypertonic?

A

Hypotonic

82
Q

Antidiuretic hormone action at V2 receptors results in what action?

A

Insertion of aquaporin water channels on the luminal side of the collecting tubules resulting in increased water reabsorption

83
Q

What substances are reabsorbed in the early proximal convoluted tubule?

A

Glucose, amino acids, bicarbonate, sodium, chloride, and water

84
Q

What does angiotensin II do in the early proximal convoluted tubule?

A

Angiotensin II stimulates the sodium/hydrogen ion exchange, causing increased sodium and water reabsorption, thereby permitting contraction alkalosis

85
Q

How does parathyroid hormone increase phosphate excretion in the kidney?

A

It inhibits Na+/phosphate cotransport in the proximal tubule

86
Q

The ratio of solute concentration in the tubular fluid vs plasma (TF/P) can indicate the level of secretion or reabsorption of that solute along the proximal renal tubule. If the TF/P ratio of that solute is less than that of inulin, there is net _____ (reabsorption/secretion) along the proximal tubule.

A

Reabsorption

87
Q

Which exogenous substance filtered at the glomerulus quickly increases in concentration along the proximal tubule because there is net secretion?

A

Para-aminohippurate

88
Q

Along the length of the proximal tubule, does the relative concentration of chloride increase, decrease, or stay the same?

A

Increases

chloride is reabsorbed distally in the nephron

89
Q

The ratio of solute concentration in the tubular fluid vs plasma (TF/P) can indicate the level of secretion or reabsorption of that solute along the proximal renal tubule. Because the TF/P ratio of chloride, potassium, sodium, phosphate, bicarbonate, amino acids, and glucose is less than that of inulin, there is net _____ (reabsorption/secretion) along the proximal tubule.

A

Reabsorption

90
Q

The concentration of amino acids in urine along the length of the proximal tubule decreases; therefore, there is _____ (net reabsorption/net secretion/balanced reabsorption and secretion).

A

Net reabsorption

amino acids are entirely reabsorbed within the proximal tubule

91
Q

The concentration of sodium ion along the length of the proximal tubule remains constant; therefore, there is _____ (net reabsorption/net secretion/balanced reabsorption and secretion).

A

Net reabsorption

92
Q

Reabsorption of which electrolyte drives water reabsorption, thus nearly matching total osmolarity throughout the length of the proximal tubule?

A

Sodium

93
Q

The concentration of bicarbonate along the length of the proximal tubule decreases; therefore, there is _____ (net reabsorption/net secretion/balanced reabsorption and secretion).

A

Net reabsorption

bicarbonate is reabsorbed more avidly than most other ions

94
Q

Along the length of the proximal tubule, does the concentration of inulin increase, decrease, or stay the same as water is reabsorbed?

A

Increases, because there is no net secretion or reabsorption of inulin

95
Q

What five actions of angiotensin II serve to increase intravascular volume and blood pressure?

A

Vasoconstriction, stimulation of sodium resorption in the proximal tubule, the release of aldosterone from the adrenal cortex, the release of antidiuretic hormone from the posterior pituitary, and the stimulation of thirst via the hypothalamus

96
Q

What is the physiologic function of renin?

A

Renin cleaves angiotensinogen from the liver into angiotensin I

97
Q

What is the site of action of angiotensin-converting enzyme?

A

The lungs

98
Q

Angiotensin I is cleaved to angiotensin II by what enzyme?

A

Angiotensin-converting enzyme; the reaction occurs in the lungs

99
Q

One action of angiotensin II is to stimulate the release of aldosterone from which organ?

A

The adrenal cortex

100
Q

When blood pressure drops, what proteolytic enzyme is released by the kidneys?

A

Renin

101
Q

Antidiuretic hormone primarily regulates _____ (osmolarity/blood volume), while aldosterone primarily regulates _____ (osmolarity/blood volume). However, in _____ (low/high) volume states, both antidiuretic hormone and aldosterone act to protect _____ (osmolarity/blood volume).

A

Osmolarity; blood volume; low; blood volume

102
Q

One action of angiotensin II is to stimulate the release of antidiuretic hormone from which gland?

A

The posterior pituitary

103
Q

What hormone, which is released from the atria, may act as a "check" on the renin-angiotensin system to prevent volume overload?

A

Atrial natriuretic peptide

104
Q

What are the effects of aldosterone secretion?

A

Aldosterone secretion from the adrenal cortex increases sodium channel and sodium/potassium pump insertion in principal cells and enhances potassium and hydrogen excretion by upregulating potassium channels in the principal cells and hydrogen ion channels in the intercalated cells. These actions create a favorable gradient for sodium and water reabsorption

105
Q

Atrial natriuretic peptide _____ (decreases/increases) renin secretion and _____ (decreases/increases) the glomerular filtration rate.

A

Decreases; increases

106
Q

Juxtaglomerular apparatus cells are modified cells of what type?

A

Smooth muscle

107
Q

What stimulates the macula densa of the nephron leading to release of renin?

A

Decreased sodium delivery to the macula densa cells

108
Q

What is the name of the cell type that produces renin in the kidney?

A

Juxtaglomerular cells

109
Q

Which hormone in the renin-angiotensin-aldosterone system alters baroreceptor response to prevent reflex bradycardia?

A

Angiotensin II; otherwise, the increase in blood pressure caused by angiotensin II would lead to a slower heart rate

110
Q

Juxtaglomerular cells, which are components of the juxtaglomerular apparatus, are modified smooth muscle cells of what arteriole of the glomerular vasculature?

A

The afferent arteriole

111
Q

What two components are part of the juxtaglomerular apparatus of the kidney?

A

Juxtaglomerular cells and macula densa

112
Q

The macula densa, which is a component of the juxtaglomerular apparatus, senses levels of which ion?

A

Sodium

113
Q

The macula densa, which is a component of the juxtaglomerular apparatus, is part of what section of the kidney nephron?

A

The distal convoluted tubule

114
Q

What are three triggers of renin release by the juxtaglomerular cells?

A

Decrease in renal blood pressure, decrease in sodium delivery to the distal tubule, and increase in sympathetic tone

115
Q

What are the results of renin release by the juxtaglomerular cells?

A

Angiotensin II and aldosterone levels increase, leading to increased circulating volume and blood pressure

116
Q

By what mechanism does the juxtaglomerular apparatus maintain and regulate the glomerular filtration rate?

A

Via the renin-angiotensin system

117
Q

What enzyme is released by the juxtaglomerular cells in response to decreased renal arterial pressure and increased renal sympathetic discharge (β1 effect)?

A

Renin

118
Q

What hormone is released by the endothelial cells of renal peritubular capillaries in response to hypoxia?

A

Erythropoietin

119
Q

What enzyme from the kidney is activated by parathyroid hormone and what is the function of that enzyme?

A

1α-Hydroxylase, which converts 25-OH vitamin D to 1,25(OH)2 vitamin D

120
Q

What effect do prostaglandins have on glomerular filtration rate?

A

They increase glomerular filtration rate by dilating the afferent arteriole

121
Q

What class of drugs can cause acute renal failure by inhibiting the renal production of prostaglandins?

A

Nonsteroidal antiinflammatory drugs

122
Q

What is the effect of nonsteroidal antiinflammatory drugs on the afferent arteriole of the kidney glomerulus?

A

Prevention of the vasodilation of the afferent arteriole by prostaglandins, reducing the glomerular filtration rate

123
Q

What are the direct and indirect effects of parathyroid hormone on the kidneys?

A

Parathyroid hormone directly acts on the kidney to increase renal calcium reabsorption and decrease renal phosphate reabsorption; it acts indirectly by stimulating the proximal tubule cells to make 1,25(OH)2 vitamin D, which increases the intestinal absorption of both calcium and phosphate

124
Q

Name four key hormones/enzymes released by the kidney that contribute to its endocrine function.

A

Erythropoietin, 1α-hydroxylase, renin, and prostaglandins

125
Q

Which cells of the collecting tubules have antidiuretic hormone receptors?

A

The principal cells

126
Q

What is the effect of atrial natriuretic peptide on the kidney's glomerular filtration rate and sodium excretion?

A

It increases both the glomerular filtration rate and sodium filtration, with no compensatory sodium reabsorption in the distal nephron to lower volume

127
Q

On what segment of the kidney nephron does aldosterone exert its effects?

A

The distal convoluted tubule

128
Q

Which hormone is secreted by the parathyroid gland in response to a decrease in plasma calcium?

A

Parathyroid hormone

129
Q

Parathyroid hormone increases serum calcium levels by acting on which two target organs?

A

Kidney and bone

130
Q

On what segments of the kidney nephron does parathyroid hormone exert its effects?

A

The proximal and distal convoluted tubules, increasing calcium reabsorption and phosphate secretion

131
Q

Which vitamin does parathyroid hormone stimulate conversion of to an active form and what is the effect of this vitamin on the gut?

A

1,25(OH)2 vitamin D, which increases both calcium and PO43- absorption from the gut

132
Q

What is the effect of angiotensin II on the glomerular filtration rate and thus the filtration fraction?

A

Angiotensin II increases the glomerular filtration rate and filtration fraction by increasing the vasoconstriction of the efferent arteriole; there is a compensatory increase in sodium reabsorption in the proximal and distal nephron

133
Q

What hormone is secreted by the pituitary in response to increased plasma osmolarity?

A

Antidiuretic hormone (vasopressin)

134
Q

Which hormone is secreted by the adrenal cortex in response to decreased blood volume (via angiotensin II) and increased plasma potassium?

A

Aldosterone

135
Q

What effect does antidiuretic hormone have on the number of water channels and thus reabsorption of water in the collecting tubule of a kidney nephron?

A

Antidiuretic hormone increases the number of water channels and thus increases water reabsorption

136
Q

What are the effects of aldosterone on the kidney?

A

Aldosterone increases sodium reabsorption, indirectly increases potassium secretion, and increases hydrogen ion secretion

137
Q

How does angiotensin II help to decrease additional volume loss in low-volume states?

A

By increasing glomerular filtration rate and filtration fraction, via constriction of the efferent arteriole, while simultaneously increasing sodium reabsorption proximally and distally

138
Q

Name six things that can cause hyperkalemia by causing a shift of potassium out of cells.

A

Insulin deficiency, β-blockers, acidosis, hyperosmolarity, digitalis, and cell lysis

139
Q

Name four things that can cause hypokalemia by causing a shift of potassium into cells.

A

Insulin, β-agonists, alkalosis, and hypo-osmolarity

140
Q

By what mechanism does insulin cause potassium shifts across cellular membranes?

A

Insulin stimulates the sodium-potassium adenosine triphosphatase pump to pump potassium into the cell in exchange for sodium out of the cell

141
Q

By what mechanism does stimulation of the β-adrenergic system cause hypokalemia?

A

By stimulating the sodium-potassium adenosine triphosphatase pump to pump potassium into the cell in exchange for sodium out of the cell

142
Q

By what mechanism does acidosis or alkalosis cause potassium shifts out of or into the cell, respectively?

A

Changes in pH alter the activity of the K+/H+ exchanger; in acidosis (high H+ concentration), H+ is sequestered in cells in exchange for K+, increasing serum K+ concentrations; the opposite occurs with alkalosis

143
Q

By what mechanism does digitalis cause hyperkalemia?

A

Digitalis blocks the sodium-potassium adenosine triphosphatase pump from pumping potassium into the cell in exchange for sodium, thus leaving the potassium outside of the cell

144
Q

In the state of respiratory acidosis, the renal compensatory response has what effect on serum bicarbonate?

A

Bicarbonate levels increase in serum

145
Q

What is the primary electrolyte disturbance in metabolic acidosis?

A

Decreased serum bicarbonate

146
Q

What is the compensatory respiratory response to metabolic acidosis and in what direction does partial pressure of carbon dioxide change?

A

Hyperventilation, which causes the partial pressure of carbon dioxide to decrease

147
Q

What is the primary electrolyte disturbance in metabolic alkalosis?

A

Increased serum bicarbonate

148
Q

What is the compensatory respiratory response to metabolic alkalosis and in what direction does partial pressure of carbon dioxide change?

A

Hypoventilation, which causes the partial pressure of carbon dioxide to increase

149
Q

What is the primary electrolyte disturbance in respiratory acidosis?

A

Increased partial pressure of carbon dioxide

150
Q

In the state of respiratory alkalosis, in what direction does bicarbonate change as a result of a compensatory response?

A

Bicarbonate decreases

151
Q

What is the primary electrolyte disturbance in respiratory alkalosis?

A

Decreased partial pressure of carbon dioxide

152
Q

Using the Henderson-Hasselbach equation, what can be calculated if bicarbonate and partial pressure of carbon dioxide are known?

A

pH, because pH = pKa + log (bicarbonate / [0.03] partial pressure of carbon dioxide)

153
Q

In metabolic acidosis, a reduction in bicarbonate is the primary disturbance. How is the expected compensatory change in partial pressure of carbon dioxide calculated?

A

Winter's formula: partial pressure of carbon dioxide = 1.5(bicarbonate) + 8 ± 2

154
Q

To compensate, PCO2 _____ (decreases/increases) by _____ mmHg for every 1 mEq/L increase in HCO3-.

A

Increases; 0.7; 1

155
Q

What is the formula for calculating the anion gap?

A

Anion gap = sodium - (chloride + bicarbonate)

156
Q

Acidemia is defined by an arterial pH value that is _____ (greater than/less than/equal to) 7.4, and alkalemia is defined by an arterial pH value that is _____ (greater than/less than/equal to) 7.4.

A

Less than; greater than

157
Q

What primary acid-base disturbance is present when the arterial pH is <7.4 and the partial pressure of carbon dioxide level is <40 mmHg?

A

Metabolic acidosis

158
Q

What is the differential diagnosis for a non-anion gap metabolic acidosis?

A

Diarrhea, glue sniffing, renal tubular acidosis, and hyperchloremia

159
Q

Hypoventilation can lead to which state of acid-base imbalance?

A

Respiratory acidosis

160
Q

What mechanisms or disease states can lead to respiratory acidosis?

A

Airway obstruction, acute or chronic lung disease, opioids, narcotics, sedatives, and the weakening of respiratory muscles

161
Q

What primary acid-base disturbance is present when the arterial pH is <7.4 and the partial pressure of carbon dioxide level is >40 mmHg?

A

Respiratory acidosis

162
Q

What are the possible causes of metabolic acidosis with an anion gap?

A

Methanol, Uremia, Diabetic ketoacidosis, Paraldehyde/phenformin, Iron tablets/Isoniazid, Lactic acidosis, Ethylene glycol, and Salicylates (remember: MUD PILES)

163
Q

A normal anion gap falls into what range of values?

A

8-12 mEq/L

164
Q

What primary acid-base disturbance is present when the arterial pH is > 7.4 and the partial pressure of carbon dioxide level is<40 mmHg?

A

Respiratory alkalosis

165
Q

What is the primary acid-base disturbance when the arterial pH is > 7.4 and the partial pressure of carbon dioxide level is > 40 mmHg?

A

Metabolic alkalosis

166
Q

Hyperventilation, seen early in high-altitude exposure, can lead to a _____ (respiratory/metabolic) _____ (acidosis/alkalosis).

A

Respiratory, alkalosis

167
Q

If the arterial pH is > 7.5 and the partial pressure of carbon dioxide is > 40 mmHg, which acid/base compensatory mechanism is in use?

A

Respiratory compensation (hypoventilation to increase carbon dioxide)

168
Q

What type of acid-base disturbance does aspirin overdose initially lead to? As the aspirin is metabolized, what type of acid-base disturbance does it become?

A

Respiratory alkalosis initially, then metabolic acidosis

169
Q

What are four causes of metabolic alkalosis?

A

Vomiting, diuretic or antacid use, and hyperaldosteronism

170
Q

In type 4 renal tubular acidosis, there is hypoaldosteronism leading to hyperkalemia, which causes inhibition of _____ excretion.

A

Ammonia

171
Q

In type 1 renal tubular acidosis, there is a defect in the hydrogen ion pump, leading to a failure to _____ (acidify/alkalinize) urine.

A

Acidify

as a result, the body's pH decreases

172
Q

In type 2 renal tubular acidosis, there is a failure to reabsorb _____.

A

Bicarbonate

173
Q

Which two types of renal tubular acidosis are associated with hypokalemia?

A

Type 1 and type 2

174
Q

Which type of renal tubular acidosis is characterized by a defect in the hydrogen pump, type 1, 2, or 4?

A

Type 1

175
Q

Which type of renal tubular acidosis is characterized by the inhibition of ammonia excretion, type 1, 2, or 4?

A

Type 4

176
Q

Which type of renal tubular acidosis is a defect of the collecting tubules?

A

Type 1; the collecting tubules cannot secrete H+ ions

177
Q

Which type of renal tubular acidosis is characterized by renal loss of bicarbonate, type 1, 2, or 4?

A

Type 2

178
Q

If a patient had a slightly elevated blood pH, a low plasma bicarbonate level, and a slightly low blood hydrogen ion level, what acid-base disturbance would be present?

A

Chronic respiratory alkalosis

179
Q

If a patient had a high blood pH, a slightly low plasma bicarbonate level, and a very low blood hydrogen ion level, what acid-base disturbance would be present?

A

Acute respiratory alkalosis

180
Q

If a patient had a low blood pH, a low plasma bicarbonate level, and a high blood hydrogen ion level, what acid-base disturbance would be present?

A

Metabolic acidosis

181
Q

If a patient had a low blood pH, a slightly elevated plasma bicarbonate level, and a high blood hydrogen ion level, what acid-base disturbance would be present?

A

Acute respiratory acidosis

182
Q

If a patient had slightly low blood pH, a high plasma bicarbonate level, and a slightly elevated blood hydrogen ion level, what acid-base disturbance would be present?

A

Chronic respiratory acidosis

183
Q

If a patient had high blood pH, a high plasma bicarbonate level, and a low blood hydrogen ion level, what acid-base disturbance would be present?

A

Metabolic alkalosis

184
Q

If a patient has a pH of 7.33, a plasma bicarbonate of 12, and a partial pressure of carbon dioxide of 21, that patient has a _____ (compensated/uncompensated) metabolic _____ (acidosis/alkalosis).

A

Compensated; acidosis

185
Q

If a patient has a pH of 7.18, a plasma bicarbonate of 14, and a partial pressure of carbon dioxide of 40, that patient has a _____ (compensated/uncompensated) metabolic _____ (acidosis/alkalosis).

A

Uncompensated; acidosis

186
Q

If a patient has a pH of 7.50, a plasma bicarbonate of 31, and a partial pressure of carbon dioxide of 40, that patient has a _____ (compensated/uncompensated) metabolic _____ (acidosis/alkalosis).

A

Uncompensated; alkalosis

187
Q

If a patient has a pH of 7.40, a plasma bicarbonate of 32, and a partial pressure of carbon dioxide of 48, that patient has a _____ (compensated/uncompensated) metabolic _____ (acidosis/alkalosis).

A

Compensated; alkalosis