Renal III Flashcards

1
Q

Most potassium reabsorption at the proximal tubule is _____

A

passive

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2
Q

Why is there is no conflict between sodium and potassium reabsorption?

A

Because in the grand scheme of things its relatively small amounts, there may be some pathological situations where one may drive the other away from homeostasis but that is relatively rare

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3
Q

Potassium acts directly on cells, independent of the _____ system

A

RAS

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4
Q

_______ is reabsorbed in proximal tubule and ascending limb of loop of Henle

A

Potassium

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5
Q

At _____ [K+] excretion =10-20% of filtered load (reabsorption is less than filtered)

A

normal

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6
Q

Low [K+] deceases _______ release, reducing secretion which reduces excretion (2%)

A

aldosterone

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7
Q

High [K+] stimulates _____ release directly and increases secretion and thus excretion (10-150%)

A

aldosterone

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8
Q

Aldosterone also plays a critical role in K+ ________ (enhances secretion in P cells)

A

homeostasis

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9
Q

Plasma (ECF) K+ needs to be maintained within a ____ range (3.5-5 mM). Alterations in body K+ levels affects the ______ membrane potential of all cells

A

narrow, resting

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10
Q

What are two reasons for why is it important to maintain adequate amounts of potassium?

A
  1. Potassium is mainly found intracellularly
  2. How much potassium that is in the ECF will determine the amount of potassium in the ICF which will determine the resting membrane potential of a cell
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11
Q

During a state of _______ (higher potassium in the ECF) there is a reduced amount of potassium that leaks out of the cell, more is being retained in the cell itself, which causes the resting membrane potential to become depolarized. Causes ______ of the cells

A

Hyperkalemia, hyperexcitation

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12
Q

During a state of ______ (lower potassium in the ECF) that will facilitate more potassium to leave the cell, which would hyperpolarize the cell and cause a more negative resting membrane potential. Now a stimulus that would normally cause an action potential won’t because now it needs a _____ depolarization to fire

A

Hypokalemia, stronger

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13
Q

Potassium balance is particularly important in ____ tissues such as the heart or skeletal muscles

A

excitable

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14
Q

__________ causes muscle weakness because its more difficult for hyperpolarized motor neurons and muscles to fire AP’s (failure of respiratory and cardiac muscles is particularly worrisome)

A

Hypokalemia

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15
Q

________ more dangerous, initially leads to hyperexcitability. Eventually cells are unable to repolarize and actually become less excitable and can lead to life threatening arrhythmias in the heart

A

Hyperkalemia

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16
Q

Disturbances in K+ balance may result from _____ dysfunction, eating disorders, loss of K+ in diarrhea or use of ____ that prevent kidneys from properly reabsorbing K+

A

kidney, diuretics

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17
Q

______ responses are critical in restoring the normal state, particularly when ECF volume decreases or osmolarity deviates.

A

Behavioral

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18
Q

_______ _____ is normally the only way to replace lost water and eating salt is the only way to raise the body’s Na+ content.

A

Drinking water

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19
Q

The act of drinking relieves thirst, water does not actually have to be _______

A

absorbed

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20
Q

Unknown receptors in the _____/______ respond to water by decreasing thirst and decreasing AVP release

A

mouth/pharynx

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21
Q

The region responsible for both thirst as well as sodium appetite are in the _______, they have osmo-sensitive neurons that respond to increase in osmolarity

A

hypothalamus

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22
Q

The act of drinking acts as a _______ mechanism assuming that the fluid that you did take in will be adequate to bring osmolarity back down to normal.

A

feedforward

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23
Q

Thirst comes in ______; this is to prevent swinging too far in the opposite direction

A

waves

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24
Q

While the RAS also is a stimulus of thirst, _______ is considered the main driver

A

osmolarity

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25
Q

_______ behaviors help prevent dehydration

A

Avoidance

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26
Q

Increased aldosterone and ANGII increases _____ appetite

A

sodium

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27
Q

Increased [Na+] of blood plasma, cerebrospinal fluid, post-ingestive signals from the gut sensed via the vagus nerve, and circulating & CNS peptide hormones/neuromodulators cause a _______ in sodium appetite

A

decrease

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28
Q

The ___ system responds to changes in blood volume and pressure, the _____ system responds to changes in blood volume and/or ________ and ______ mechanisms respond to both

A

CV, renal, osmolarity and behavioral

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29
Q

Normally volume and osmolarity can be kept within a narrow range but under certain circumstances becomes out of _____. Osmolarity and blood volume can change _________ resulting in different scenarios.

A

balance, independently

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30
Q

1- Ingestion of hypertonic saline: ↑ volume, ↑ osmolarity: may occur with ? and ? at the same time, net results= ingestion of hypertonic saline (salt>water). You need to therefore ? to match what was taken in

A

eating salty foods, drinking liquids, excrete the solute and liquid

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31
Q

2- Ingestion of isotonic saline: ↑ volume, no change in osmolarity: if salt and water ingested is equivalent to ______ solution

A

isotonic

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32
Q

3- Drinking larg amount of water: ↑ volume, ↓ osmolarity: simply drinking pure water without ?. The kidneys cannot excrete pure water, so some solute would be lost in this situation, compensation is ______

A

ingesting solute, imperfect

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33
Q

4- Eating salt without drinking water: No volume change, ↑ osmolarity: eating salt without ?, increases ECF osmolarity shifting water from cells to ECF, This triggers intense ____ and kidneys make _______ _____

A

drinking water, thirst, concentrated urine

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34
Q

5- Replacement of sweat loss with plain water: No change in volume, ↓ osmolarity: water and solutes would be lost in sweat but only _____ is replaced. This can lead to ______ or ________. Sports drinks help to replace fluid and solutes lost

A

water, hypokalemia, hyponatremia

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35
Q

6- dehydration: ↓ volume, ↑ osmolarity: dehydration could be due to ____ _____ (water loss from lungs can double, sweat loss can increase from 0.1-5 L) or ______ (excessive fluid loss in feces). This can result in inadequate _____ (decreased blood volume) and cell _______. Increases ____ intake

A

heavy exercise, diarrhea, perfusion, dysfunction, water

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36
Q

7- hemorrhage: ↓ volume no change in osmolarity: _______, need blood transfusion or ingestion of ______ solution.

A

hemorrhage, isotonic

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37
Q

8- Incomplete compensation for dehydration: ↓ volume, ↓ osmolarity: may result from incomplete compensation for _______, but is uncommon

A

dehydration

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38
Q

Of the 8 possibilities between, which is the most common?

A

6, increase in osmolarity, with a decrease in volume. AKA dehydration

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39
Q

Pathological hyponatremia, causes an increase in _____ secretion

A

aldosterone

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40
Q

Severe dehydration results in a loss of ECF volume, decrease in blood pressure and an increase in osmolarity, the ________ _____ aim to restore these three factors

A

compensatory mechanisms

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41
Q

Severe dehydration has compensatory mechanisms aim to restore a loss of ECF volume, decrease in blood pressure and an increase in osmolarity by:

A
  1. Conserving fluid to prevent additional loss
  2. Trigger cardiovascular reflexes to increase blood pressure
  3. Stimulate thirst so normal fluid volume and osmolarity can be restored
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42
Q

Four compensatory mechanisms with redundant overlap overcome the symptoms of dehydration:

A
  1. Cardiovascular mechanisms
  2. Renin-angiotensin system
  3. Renal mechanisms
  4. Hypothalamic mechanisms
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43
Q

During severe dehydration, decreased ECF volume (blood pressure) would signal to increase ______ release but at the same time an increased ______ inhibits aldosterone release

A

aldosterone, osmolarity

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44
Q

Osmolarity control in severe dehydration situation reigns and aldosterone is not secreted, if it were that would cause ____ _______ which would worsen the already high osmolarity

A

Na+ reabsorption

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45
Q

Carotid and aortic baroreceptors signal CVCC

a. Heart rate goes up as SA node control shifts from _______ to _______
b. Force of ventricular contraction increases from sympathetic stimulation, increases _____ ______. Causes an increase in ____
c. Sympathetic input to arterioles ______ peripheral resistance, increases ___
d. Sympathetic ________ of afferent arterioles in kidney decreases GFR, conserving fluid
e. Increased _______ activity at granular cells increases renin secretion

A

a. parasympathetic to sympathetic
b. stroke volume, CO
c. increases, BP
d. vasoconstriction
e. sympathetic

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46
Q

Decreased blood pressure directly decreases ____

A

GFR

47
Q

Paracrine feedback at macula densa cells causes granular cells to release _____

A

renin

48
Q

______ cells respond to decreased blood pressure by releasing renin

A

Granular

49
Q

Decreased blood pressure, volume, increased osmolarity, and increased ANGII all stimulate ________ and the thirst centers of the _______. ANG II reinforces ___ response

A

vasopressin, hypothalamus, CV

50
Q

Decreased blood volume and pressure results in:

____ attempt by the CVCC to maintain blood pressure

Restoration of volume by ____ conservation and fluid intake

Restoration of normal osmolarity by decreased ___ ______ and increased water reabsorption and intake.

A

Rapid, water, Na+ reabsorption

51
Q

The pH of a solution is a measurement of its ?

A

H+ concentration

52
Q

The H+ concentration of normal arterial plasma is very ____ compared to other ions, Na+ is usually expressed on a ______ pH scale of 0-14

A

small, logarithmic

53
Q

pH of 7 is _____, if a solution is below 7.0 the H+ concentration is greater than 1x10-7M and considered ____. If a solution is above pH of 7.0 it has a [H+] below 1x10-7 M and is considered _____ (basic)

A

neutral, acidic, alkaline

54
Q

Normal pH of the body is ____, slightly ______

A

7.40, alkaline

55
Q

A change of 1 pH unit represents a ___-fold change in H+ concentration

A

10

56
Q

Commonly look at ____ pH when considering ECF and whole body pH

______: 7.38-7.42

A

plasma, Normal

57
Q

The only time we see ______ of the norm is looking at areas that are technically considered “outside the body” or a “continuation of the external environment” like the GI tract

A

deviations

58
Q

pH changes can _____ proteins

A

denature

59
Q

pH is closely ____, intracellular proteins such as enzymes and membrane channels sensitive to pH changes. The function of these proteins depend on their normal three-dimensional ______

A

regulated, structure

60
Q

Very low pH (excess H+) can result in ______:

CNS depression, confusion, coma

A

acidosis

61
Q

Changes in H+ concentration results in disruptions in ____ ____ altering the structure

A

hydrogen bonds

62
Q

High pH, low H+ can result in _______:

hyperexcitability in sensory neurons and muscles, sustained respiratory muscle contraction

A

alkalosis

63
Q

In day to day functioning the body is challenged by intake and production of _____ more than _____

A

acids, bases

64
Q

Acid input is a result of ____ as well as acids produced during ______. The largest source of acid on a daily basis is ____ from aerobic metabolism

A

diet, metabolism, CO2

65
Q

pH homeostasis depends on three mechanisms: ?

A

Buffers (first line of defense)
Ventilation (handles 75% of disturbances)
Renal regulation of H+ and HCO3- (slowest)

66
Q

Buffers only function in the _____ range of pH, but when they go ______ of it that’s when the other two mechanisms kick in

A

normal, outside

67
Q

_____ systems include proteins, phosphate ions and HCO3-

A

Buffer

68
Q

A ______ is a molecule that moderates, but does not prevent changes in pH by combining with or releasing H+

A

buffer

69
Q

In the absence of a buffer adding acid to a solution causes a _____ change in pH, but in the presence of buffers the H+ added is bound and pH change is slightly ______ or may even be unnoticeable

A

sharp, moderated

70
Q

Buffers are found within cells and in the plasma. ________ buffers include cellular proteins and phosphate ions

A

Intracellular

71
Q

We measure pH generally of the _____

A

ECF

72
Q

HCO3- , the most ______ extracellular buffer system

A

important

73
Q

According to law of ____ _____ any change in amount of CO2, HCO3- or H+ in solution causes reaction to shift until new equilibrium is reached

A

mass action

74
Q

Increasing CO2 shifts equation to ______ creating one H+ and one HCO3-

A

right

75
Q

Adding H+ (through a metabolic source i.e. lactic acid) shifts the equation to the _____, HCO3- acts as buffer creating carbonic acid

A

left

76
Q

Because of the already _____ concentration of bicarbonate, you need to either gain/lose a significant amount for it to affect the equilibrium

A

high

77
Q

_______ compensates for pH disturbances

A

Ventilation

78
Q

_______ and _____ chemoreceptors sense changes in plasma PCO2 and/or H+ and signal to the respiratory control center to adjust ventilation accordingly

A

Peripheral, central

79
Q

Alterations in ventilation can correct disturbances in acid-base balance as well as cause them:
__________: right shift
__________: left shift

A

Hypoventilation, Hyperventilation

80
Q

In response in increased CO2, increased pH, you would have an increase in ____ and _____ of breathing so you would increase the _______ of CO2, which would cause levels of CO2 in the plasma to ____ and H+ to drop

A

rate and depth, exhalation, drop

81
Q

When you have low levels of H+ in plasma, you’d have lower levels of ____ as well, ____the rate and depth of breathing which would bring the pH back down to normal

A

CO2, reduce

82
Q

_____ use ammonia and phosphate buffers

A

Kidneys

83
Q

The kidneys handle the remaining ____ of pH disturbances slowly through two mechanisms

A

25%

84
Q

Kidneys handle the remaining 25% of pH disturbances slowly through two mechanisms: ?

A
  1. Directly, by altering the rates of excretion or reabsorption of H+
  2. Indirectly, by changing the rate at which HCO3- buffer is reabsorbed or excreted.
85
Q

In general, during _____ excess H+ is buffered by ammonia within tubule cells or enters lumen and is buffered by phosphate ions. H+ is not filtered, enters tubule via _____ only

A

acidosis, secretion

86
Q

The kidney secretes H+, which is buffered in the urine by _______ and ________ _____. It reabsorbs bicarbonate to act as an extracellular buffer

A

ammonia, phosphate anions

87
Q

The ____ tubule secretes H+ and reabsorbs HCO3-

A

proximal

88
Q

Hydrogen is secreted through a ?

A

sodium-hydrogen exchanger

89
Q

______ reabsorption drives all transport within the proximal tubule

A

Sodium

90
Q

There are no bicarbonate transporters on the _____ membrane, so the secretion of hydrogen allows to conversion of bicarbonate back to CO2 so that it can get into the ______ tubule cells

A

apical, proximal

91
Q

Another mechanism for bicarbonate creation and reabsorption as well as a potential buffer for hydrogen would be the use of _______ within proximal tubule cells

A

glutamine

92
Q

Order these statements for “proximal tubule secretion:”
1. CO2 diffuses into cell
2. HCO3- is reabsorbed with Na+
3. NHE secretes H+
4. Glutamine is metabolized to ammonium ion and HCO3-
5. CO2 combines with water to form H+ and HCO3-
6. H+ in filtrate combines with filtered HCO3- to form CO2
7. NH4+ is secreted and excreted
8. H+ is secreted again

A

3, 6, 1, 5, 8, 2, 4, 7

93
Q

The _____ nephron controls acid excretion

A

distal

94
Q

Initial portion of the _______ ____ plays a significant role in the fine regulation of acid-base balance

A

collecting duct

95
Q

_______: type B intercalated cells in collecting duct function in this. HCO3- and K+ are excreted; H+ is reabsorbed

A

Alkalosis

96
Q

Type B has the same transporters as Type A but on the ______ membrane, which means that the ______ is switched

A

opposite, polarity

97
Q

Type __: hydrogen-ATPase on apical, and bicarbonate-chloride transporters and potassium leak channels on the basolateral membrane
Type __: hydrogen-ATPase on basolateral, and bicarbonate-chloride transporters and potassium leak channels on the apical membrane

A

A, B

98
Q

_______: type A intercalated cells in collecting duct function to increase H+ secretion and HCO3- reabsorption is usually accompanied by an increase in K+ reabsorption (hyperkalemia)

A

Acidosis

99
Q

______: type B intercalated cells in collecting duct function to increase H+ reabsorption and HCO3- secretion is usually accompanied by increase K+ secretion (hypokalemia)

A

Alkalosis

100
Q

Acid-base disturbances may be _____ or ______

A

respiratory, metabolic

101
Q

Three compensatory mechanisms (buffers, ventilation and renal excretion) take care of most ______ in plasma pH

A

variations

102
Q

Acid-base disturbances are classified both by the ______ of the pH change (acidosis or alkalosis) and by the _______ ____ (metabolic or respiratory)

A

direction, underlying cause

103
Q

By the time an acid-base disturbance causes a change in plasma pH the body’s buffers are _______ leaving ______ and _____ compensation to alleviate the change in pH

A

ineffective, respiratory, renal

104
Q

_______ _____: occurs when alveolar hypoventilation results in CO2 retention and elevated plasma CO2. -Due to ______ origin, compensation must occur via _____ mechanisms (excrete H+, reabsorb HCO3-)

A

Respiratory acidosis, respiratory, renal

105
Q

What are some examples of respiratory acidosis?

A

-Pulmonary fibrosis
-Skeletal muscle disorders: Muscular dystrophy

106
Q

_______ ______: much less common, occurs as a result of hyperventilation in the absence of increased metabolic CO2 production. Compensation occurs via _____ HCO3- excretion and H+ reabsorption

A

Respiratory alkalosis, renal

107
Q

In respiratory alkalosis:
In clinic: usually caused by excessive artificial _______
Physiological: anxiety induced ___________

A

respiration, hyperventilation

108
Q

______ _______: occurs when dietary and/or metabolic input of H+ exceeds H+ excretion

A

Metabolic acidosis

109
Q

What are two examples of metabolic acidosis?

A

Lactic acidosis
Ketoacidosis

110
Q

______ acidosis as a result of anaerobic metabolism
________ from excessive breakdown of fats and some amino acids

A

Lactic, Ketoacidosis

111
Q

________ ______: can also occur from excessive HCO3- loss (diarrhea), H+ enters blood, HCO3- enters intestine. -rarely seen clinically, usually resolved by respiratory (increased ventilation) and slow renal compensation (HCO3- reabsorbed, H+ excreted)

A

Metabolic Acidosis

112
Q

________ ______: two common causes; excessive vomiting of acidic stomach contents or excessive ingestion of bicarbonate-containing antacids

A

Metabolic alkalosis

113
Q

_____ ______: usually rapidly resolved by a decrease in ventilation, but effectiveness is limited because it can cause hypoxia. There is a renal response: HCO3- excreted, H+ reabsorbed

A

Metabolic alkalosis