Brainscape's Knowledge GenomeTM

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


See full index

Renal Final > Proximal Convoluted Tubule > Flashcards

Proximal Convoluted Tubule Flashcards

1
Q

Name three structural features of the PCT and their function.

A
  1. Apical Microvilli and basolateral folds = drastically increase surface area
  2. Tight junctions = regulate movement
  3. Paracellular spaces = between cells, some movement of fluid and ions occur through the spaces.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the permeability of water, to ions, relative to conductance in the PCT?

A

High permeability to water (has aquaporin).

  • High permeability to ions = high conductance. Many ions move through the paracellular spaces.
  • Has relatively low electrochemical gradient needed to drive transport
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does the concentration of filtrate change in the PCT?

A

Concentration of filtrate does not change under normal conditions

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

About 60-70% of __, __, __, __ and 100% of _ are reabsorbed in the PCT.

A

60-70% Na, Cl, HCO3-, K.

100% glucose

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

PCT is permeable to urea, however their concentration still increases in the PCT, why?

A

Because more water is reabsorbed than urea.

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

what is the permeability of uric acid in the PCT?

A

It is both secreted and reabsorbed, but net reabsorption usually occurs.

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

Besides PCT, where else does uric acid transport occur?

A

PCT is the ONLY place where uric acid transport occurs

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

How does glucose get reabsorbed?

A

Na/Glu cotransporter.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does it mean by Na/Glu cotransporter is a capacity-limiting system?

A

You will run out of transporter before the gradient is eliminated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Up to what concentration of glucose does complete reabsorption occur?

A

Lower than 250 mg/dL

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

how do you expect the reabsorption of glu to change when there is D-galactose and D-fructose in the filtrate?

A

Reabsorption will likely decrease, since D-galactose and D-fructose compete for the same transporter.

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

How does Amino acid get reabsorbed?

A

Na/AA cotransporter.

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

True/False. The kidney regulate blood levels of amino acids.

A

False. Liver does that.

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

How does protein-hormones like ADH, PTH, insulin get reabsorbed?

A

pinocytosis and the broken down inside the cells and then transported back into the blood.

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

Usually organic anion are secreted rather than filtered. Why?

A

They are bound to plasma proteins carrier and so they are not filtered out.

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

prostaglandins is secreted in the PCT, why might that be?

A

So that they can get transported to the DCT where they act.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is an example organic cation secretion that occurs in PCT?

A

Creatinine and others.

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

Salt reabsorption does NOT appreciably affect __ of plasma, but has major effect on __ of plasma.

A

not much affect on composition (osmolarity), but major effect on volume.

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

What creates the gradient for Salt reabsorption in PCT?

A

Na/K-ATPase. The pump operates way below saturated level at a steady state, so more Na coming into the cell will increase the rate of pumping, thus maintain gradient.

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

Name some Na-Reabsorption channels and what other compounds they operate with.

A

Na-Channels = straight Na transport through apical channels. (minor contributor)
Na/H - antiport = Bring Na and kick H out. ThIS THE MAJOR CONTRIBUTOR to Na reabsorption along first third of PCT (contributes to pH balance)
- Na/Glu symport: Depends on glucose concentration.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Name ways HCO3- is reabsorbed.

A

HCO3- / Na+ symport in a 3:1 ratio.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

In the filtrate, HCO3- react with 1 which comes from 2 antiporter and to form 3 and 4.

A
  1. H+
  2. Na/H antiporter
  3. CO2
    4 H20
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Inside the tubular cell, what’s happening to the HCO3- level as H+ is being kicked out via the Na/H antiporter?

A

More HCO3- is created as H+ is being kicked to the lumen. This extra HCO3- is being transported back to the blood via HCO3- / Na+ symporter in a 3:1 ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What two locations of the tubular cell are carbonic anhydrase located?

A

On the brush border and inside the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How does Cl- get reabsorbed?

A

Cl- /Base antiporter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The Cl-/Base antiporter work in conjunction with __.

A

Na/H antiporter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

The net result of the Cl-/ Base antiporter and Na/H antiporter is transport of __ into the cell.

A

NaCl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the predominant mode of Na transport in the latter two thirds of the proximal tubule?

A

The net result of the Na/H antiporter and the Cl/Base antiporter.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Paracellular reabsorption of Cl- is the main mode of reabsorption during which part of the proximal tubule?

A

The latter portion. This transport is driven by a rise in Cl- concentration in the early segments of the tubule.

30
Q

On the basolateral part of the tubular cell, what transporter helps Cl get back to he blood?

A

K/Cl symporter

31
Q

In the PCT, is the gradient for water reabsorption small or big?

A

small gradient

32
Q

How does water reabsorption mainly occur in the PCT and is it via transcellular or paracellular?

A

Paracellular is the main way.

33
Q

What is the main inhibitor of water reabsoprtion in the PCT?

A

Solute concentration. Decrease of solute concentration will decrease water reabsorption. Because the PCT is pretty impermeable to solute, water is able to follow.

34
Q

If you have a high protein diet, how would filtrate urea concentration be affected?

A

High urea

35
Q

What is acetozolamide and where does it have it’s effect?

A

it’s an osmotic diuretic that works by blocking transport in the PCT

36
Q

What transporter does ang II stimulate in the PCT?

A

Na/H anitporter

37
Q

Under normal condition, what percent of the following are reabsorbed?

  1. H20
  2. Na
  3. Glu
  4. Urea
A
  1. 99%
  2. 99.5%
  3. 100%
  4. 50%
38
Q

What is the total liter amount that is filtered per day for the following

  1. H20
  2. Na
  3. Glu
  4. Urea
A
  1. 180
  2. 630
  3. 180
  4. 56
39
Q

What is the amount that is excreted by day for the following in liter?

  1. Water
  2. Na
  3. Glucose
  4. Urea
A
  1. 1.8
  2. 3.2
  3. 0
  4. 28
40
Q

What is fractional excretion?

A

Of the total amount that is filtered, the fraction that is excreted

41
Q

What would happen to the fractional excretion if you were on a low sodium diet for 5 days?

A

FE would decrease.

42
Q

What portion (s) of the nephron would you likely to find leaky tight junctions?

A

First part of the PCT

43
Q

What is the leaky tight junction important for?

A

important for setting gradient

44
Q

WHat is the tubular fluid to plasma ration?

A

the ratio of a substance to what it was in plasma to what it is in the tubules after it has been filtered.

45
Q

What compounds in PCT are reabsorbed isoosmotically and thus produces a straight horizontal line on the plasma concentration and PCT length?

A

Na, K,

46
Q

A curve downward below 1 means what?

A

that they’re being reabsrobed avidly

47
Q

A upward curve above 1 means what?

A

They’re being reabsorbed, but as water leaves the tubule their concnetration increases in the tubule more then they’re being reabsorbed.

48
Q

The curve for inulin is exponetial upward becuase?

A

it’s concentration increases in the tubule because they’re not being reabosrbed nor are they secreted

49
Q

THe curve for PAH spikes really high as water is reabsrobed why?

A

it’s not being reabosrbed AND it’s being secreted.

50
Q

What side of the cell is the NA/K ATPase located?

A

basolateral membrane (closer to the capillary)

51
Q

What other substances is Na reabsorption linked to?

A

Na/Glu symporter
Na/H exchanger
N/K,2Cl transporter (loop of henle)

52
Q

What are two components that helps to create the renal medulary interstitial gradient?

A
  1. Na/K, 2Cl transporter, and

2. Urea

53
Q

if Urea and Cl- is not being reabsorbed, what other substance isn’t also being reabsorbed?

A

Na and water. Cl and Urea reabsorption is not an active process. it’s dependent on Na and water reabsroption. Cl and Urea become more concentrated in the lunimical fluid as na and water leaves and so they move as their gradient increases.

54
Q

What are some factors that can promote fluid movement into the peritubular capillaries?

A
  1. High plasma colloid osmotic pressure in the peirtubular caps
  2. Low hydrostatic pressure in caps
  3. Consequences
55
Q

True or false? Kidney regulates plasma concentration of glucose and amino acid.

A

False. Liver regulates it.

56
Q

What are three mechanism by which tubular reabsorption of glucose and amino acid can occur?

A
  1. secondary active transport
  2. Uptake across luminal membrane
  3. Exit cell through basolateral membrane by faciliated diffusion
57
Q

What are each of the answers in the above question (mechansim of tubular reabsorption of glucose and amino acid) dependent on?

A
  1. Secondary transport (Na/Glu cotransproter) on the apical membrane of lumen of tubule. as Na goes into cell, glu follows. Glu conc in side the cell increaes and goes out to capillary in the basolateral side via simple diffusion down it’s concentration
  2. Uptake across luminal membrane is coupled to Na entry down’t sits electrochemical gradient. ultimately dependent on na/K ATPase
  3. Exit cell via faciliated diffusion at he basolaeral memrbane
58
Q

Explain why urine output is increased in diabetic pts.

A

Osmolarity of urine increases due to excess glucose beyond the threshold value and so water is retained in the tubule due to the high osmolarity. In diabetic pts, their cells are dehydrated due to the increased osmolarity, fluid form cells are drawn out into the ECF. Cells sense decreased fluid and induce thirst.

59
Q

Explain the mechanism of osmotic diuretics.

A

If there are osmotically active substances thats pulling fluid into the lumen, and if you’re continuously filtering glucose into the tubule, this is going to pull Na and water into the tubular lumen leading to polyuria. after a period of time of excreting so much fluid your cells will become dehydrated and plasma osmolarity will go up and again water will be pulled from the cells into the vascular spaces and thus increase GFR.

60
Q

Explain how use of mannitol works to treat intracerebral pressure

A

when mannitol is administer, it goes to plasma and increase osmotic pressure. this icnrease will draw fluid into he vessel thus decrease interstitial (i.e. intraceerebal) pressure.

61
Q

Explain how organic anion (ie. PAH, bile salt, uric acid, creatinine) is secreted.

A

the gradient is started at the basolateral membrane with Na and other compound bringing the compound into the cell and then the cell pushes it out on the apical side into the tubular lumen.

62
Q

Explain how organic cation (ie. N, NE), acetylcholine, dopmaine, are secreted in the PCT.

A

Organic cation comes into the cell via use of Na/K ATPase, and secreted via organic catcion transporter at the apica side.

63
Q

Of the following, which ones are saturable and thus can reach a threshold: PAH, GFR, Inulin, glucose, RPF

A

PAH and Glusose saturable as they depend on transporters.

Inulin, GFR and RPF are not saturable.

64
Q

Weak acid are neutral when __.

A

protonated

65
Q

Weak bases are neutral when __

A

Deprotonated

66
Q

weak acids become neutral in what kind of solution?

A

acidic solution

67
Q

Weak bases become netural in what kind of solution?

A

Basic solution

68
Q

Explain how organic bases in the lumen can become trapped.

A

A substances that is a weak acid, and if the pH in the lumen is acidic, it will combine with the H+ and become neutral and can now get reabsorbed. A weak base however, does not become neutral in an acidic solution (urine) and so cannot get reabsorbed and thus is trapped in the urine.

69
Q

If i was to acidify urine, how would that effect reabsorption of organic acids, and organic bases?

A

Organic acids reabsorption will increase

organic bases will be excreted cuz it cannot be reabsorbed.

70
Q

If a pt overdosed on aspirin how can you help eliminate it from the patient’s body?

A

aspirin is a weak acid, and so make the urine basic by giving the patient bicarbs which will trap the weak acid and thus keep it in urine and excrete it.

71
Q

What happens to proximal tubular reabsorption if ECF volume was contracted? ECF expansion?

A

Increases reabsorption, beucase the decreased ECF will increase peitublar capillary peritubular hydrostatic pressure and increases onocotic pressure and thus draws in more stuff in. Opposite is true for ECF expansion.

Renal Final (7 decks)

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