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Physiology III Final Exam > Loop of Henle/Distal Tubule > Flashcards

Loop of Henle/Distal Tubule Flashcards

1
Q

What is the primary function of the thin descending Loop of Henle?

A

Allow for simple diffusion

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2
Q

What is the thin descending Loop of Henle highly permeable to?

A

Water

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3
Q

What is the thin descending Loop of Henle moderately permeable to?

A

Urea and sodium

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4
Q

About how much water is absorbed in the thin descending Loop of Henle?

A

20%

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5
Q

What part of the Loop of Henle absorbs 25% of sodium, chloride, and potassium (as well as some calcium bicarbonate, and magnesium)?

A

Thick ascending

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6
Q

In what part of the Loop of Henle is the sodium-potassium ATPase pump highly active?

A

Thick ascending

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7
Q

Which part of the Loop of Henle is impermeable to water?

A

Thick ascending

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8
Q

Why is it important that the thick ascending limb of the Loop of Henle is impermeable to water?

A

Makes kidneys able to dilute or concentrate the urine as needed

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9
Q

What is the first portion of the distal tubule?

A

Macula densa

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10
Q

What is the function of the macula densa?

A

Provides feedback control of GFR

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11
Q

The macula densa is a part of what complex?

A

Juxtaglomerular complex

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12
Q

What ions are absorbed by the diluting segment of the distal tubule?

A

Sodium, postassium, chloride

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13
Q

The diluting segment of the distal tubule is impermeable to what substances?

A

Water and urea

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14
Q

What moves sodium chloride from the tubular lumen into the cell in the distal tubule?

A

Sodium-chloride co-transporter

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15
Q

What moves sodium across the basolateral membrane in the distal tubule?

A

Sodium-potassium ATPase pump

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16
Q

What two cells compose the late distal tubule and cortical collecting tubule?

A

Principal cells, intercalated cells

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17
Q

Principal cells function in the reabsorption and secretion of which ions?

A

Sodium reabsorption

Potassium secretion

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18
Q

Intercalated cells function in the reabsorption and secretion of which ions?

A

Hydrogen secretion

Bicarbonate and potassium reabsorption

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19
Q

Both the late distal tubule and cortical collecting tubule are impermeable to what substance?

A

Urea

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20
Q

What happens to most of the urea found in the distal tubule?

A

Will be excreted in the urine

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21
Q

What hormone controls the reabsorption of sodium and the secretion of potassium in the late distal tubule?

A

Aldosterone

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22
Q

The permeability of the late distal tubule and cortical collecting tubule to water is dependent on which hormone?

A

ADH (vasopressin)

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23
Q

What effect do high levels of ADH have on the water permeability of the late distal tubule?

A

High permeability

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24
Q

What structure plays an important role in the final output of water and solutes in the urine?

A

Medullary collect duct

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25
Where is urea reabsorbed in the medullary collecting duct?
Medullary interstitium
26
What is the purpose of hydrogen ions being secreted against a concentration gradient in the medullary collecting duct?
Plays a role in acid-base balance
27
Pressure natriuresis and pressure diuresis are compensatory mechanisms to regulate what?
Blood pressure (function to increase arterial BP)
28
What is natriuresis?
Increased sodium ion excretion in urine to increase BP
29
What is diuresis?
Increased water excretion to regulate BP
30
Why do we only seen small changes in excretion with pressure natriuresis and pressure diuresis?
Autoregulatory mechanisms
31
Increase in what kind of pressure causes backleak of sodium into the tubular lumen and increased urine output during pressure natriuresis and diuresis?
Peritubular hydrostatic pressure
32
What effect does a reduction in angiotensin II formation have on tubular sodium reabsorption when arterial BP increases?
Decreased tubular sodium reabsorption
33
The rate of which hormone is a major determining fact for urine concentration?
ADH
34
What happens to the osmolarity of filtrate at the beginning of the proximal tubule to the end of the proximal tubule?
Stays isotonic
35
Where is water reabsorbed by osmosis in the loop of Henle?
Descending segment
36
Does tubular fluid becomes more or less concentrated as it travels into the medulla?
More
37
Is renal medulla interstitial fluid more hyper- or hypotonic?
Hypertonic
38
Which segments of the Loop of Henle are NOT permeable to water?
Thin and thick ascending
39
How are solutes transported out of the thick ascending segment of the Loop of Henle?
Active transport
40
Does tubular fluid become more dilute or more concentrated as it travels up the ascending segment of the loop of Henle?
More dilute
41
As tubular fluid enters the Loop of Henle, is it isotonic, hypertonic, or hypotonic?
Isotonic
42
As tubular fluid leaves the Loop of Henle, is it isotonic, hypertonic, or hypotonic?
Hypotonic
43
What measurement is used to assess the concentration of urine?
Urine Specific Gravity
44
Does a high specific gravity measurement mean there is high or low concentration of urine?
High
45
What are the two basic requirements for forming a concentrated urine?
High level of ADH | High osmolarity in medulla tissue
46
How do we create a hyperosmotic renal medullary interstitial fluid?
Countercurrent mechanism
47
What factors contribute to the buildup of solute concentration into the renal medulla?
Active transport of sodium from thick ascending limb to medullary interstitium Active transport of ions out of collecting ducts into medullary interstitium Diffusion of urea from inner medullary collecting ducts into medullary interstitium Low diffusion of water compared to solute reabsorption
48
What is the term for the repetitive reabsorption of the sodium chloride by the thick ascending loop of Henle and continued inflow of new sodium from the proximal tubule into the loop of Henle?
Countercurrent multiplier
49
When do the collecting ducts become permeable to fluid?
When high levels of ADH are present
50
Where do we see a high concentration of urea?
Inner medullary collecting ducts
51
What effect do the vasa recta have on the solute concentration in the renal medulla?
Preserve the high concentration levels
52
Where is the thirst center located?
Anterolateral in preoptic nucleus
53
What area promotes the release of ADH to stimulate thirst?
Anteroventral wall of third ventricle
54
What levels of plasma osmolarity increases thirst?
Increased
55
What levels of blood volume increases thirst?
Decreased
56
What levels of blood pressure increases thirst?
Decreased
57
What levels of angiotensin II increase thirst?
Increased
58
What effect does gastric distention have on thirst?
Decreased
59
What determines extracellular fluid volume?
Intake and output of fluid and sodium (habitual)
60
What happens to the kidneys if they are unable to maintain the proper balance of extracellular fluid?
1 Adjustment of BP 2 Adjustment of circulating hormones 3 Adjustment in sympathetic nervous system changes
61
What is the cost of the kidneys making systemic adjustments to compensate for imbalance of extracellular fluid?
Damage possible and energy lost
62
What is the benefit to increased blood pressure as a response to kidney damage?
Helps maintain normal sodium excretion
63
What is the cost to increased blood pressure as a response to kidney damage?
Long term high blood pressure damage to blood vessels, heart, and organs
64
What is the effect on increased blood pressure on sodium excretion?
Increases it
65
Extensive decrease in blood volume (hemorrhage) will activate what kind of nerve activity?
Sympathetic
66
Angiotensin II controls the excretion of which ions?
Sodium
67
What levels of sodium lead to decreased production of renin?
High
68
What is the relationship between angiotensin II and "salt-sensitive people"?
They are unable to stop the angiotensin II formation in response to increased sodium levels
69
What effect does increased aldosterone have on potassium excretion?
Increased
70
What effect does increased aldosterone have on sodium and water reabsorption in the cortical collecting tubules?
Increased
71
What effect do alcohol, clonidine, and haloperidol have on ADH secretion?
Inhibition
72
What effect do nausea, hypoxia, morphine, nicotine, and cyclophosphamide have on ADH secretion?
Increase

Physiology III Final Exam (6 decks)

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