Kidney Function Flashcards

1
Q

What is the clearance?

A

The volume of plasma cleared of a substance per unit of time

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2
Q

For which type of glomeruli does the loope of Henle penetrate deeper into the medulla?

A

Juxtamedullary

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2
Q

Where is Na and Water reabsorption regulated?

A

Collecting duct

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2
Q

What is the name of the Na transporters in the collecting duct?

A

ENaC - channel

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3
Q

What is a possible consequence of low [Ca++]

A

Bone fractures

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3
Q

What happens when ADH is high?

A

Water is reabsorbed in the collecting duct

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4
Q

Which part of the nephron abuts with the parent glomeruli?

A

Thick ascending tubule

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4
Q

What are the two mechanisms of regulating glomerulus pressure?

A

Myoenteric reflex

Macula densa sensing

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5
Q

How do you calculate the clearance of a substance?

A

([X]urine x Volume of urine) / Plasma conc of X

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5
Q

What mediator regulates water reabsorption in the collecting duct?

A

Vasopressin

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5
Q

Which drugs act at the distal tubule?

A

Thiazide diuretics

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6
Q

What are the two types of glomeruli?

A

Superficial corticol

Juxtamedullary

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6
Q

What do the arterioles of juxtamedullary glomeruli become?

A

Vasa recta

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6
Q

T/F the thick ascending limb is permeable to water

A

False, the tight junctions are not permeable

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7
Q

Across what range of MAP does autoregulation keep GFR constant?

A

80-180mmHg

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9
Q

What does the 3 mean in vitamin D3?

A

It has 3 hydroxy groups

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10
Q

How much plasma is reuptaken into pertubular capillaries?

A

178L per day

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11
Q

What happens with anions in the proximal tubule?

A

They follow the gradient created by Na transport

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12
Q

Where in the proximal tubule is more Cl reabsorbed?

A

In the late PT

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13
Q

What is ureamia?

A

Accumulation of waste products in the blood - not necessarily urea

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14
Q

Is bicarbonate transport in the proximal tubule transcellular or paracellular?

A

Transcellular

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15
Q

What does microalbuminurea indicate?

A

Damage to the lamina propria in advanced diabetes that is allowing albumin to filter through capillaries

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15
Q

What is side effect of frusemide use?

A

K loss

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16
Q

Sometime the most important consequence of renal failure isn’t loss of tubular secretion but rather …?

A

Loss of endocrine function

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17
Q

What is the mechanism of renin release at the macula densa?

A

Non-active contraction of the arteriole is sensed > Renin is released via an unknown mechanism

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18
Q

What happens to NaCl at the tip of the loop of Henle?

A

It is reabsorbed due to there being relatively less of it in the ECF

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19
Q

How does the water and Na reabsorption change throughout the nephron

A

70% in proximal tubule

20-25% in the Loop of Henle

5% in the distal tubule

3% in the collecting duct

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21
Q

What what plasma concentration does glucose begin to be excreted?

A

10+mmol/L

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22
Q

What is the urine output per day?

A

1-2L

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23
Q

What is the resistance of the glomerulo-capillary?

A

Negligible

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24
Q

How much penilicin is reabsorbed in the kidneys?

A

None - it is all filtrated or secreted out

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25
Q

Overall, what happens to the contents of the TAL?

A

Diluted

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26
Q

What are the 4 physiological processes that occur in the kidneys?

A

Filtration

Reabsorption

Secretion

Excretion

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27
Q

What is major substance that is reabsorbed in the thin descending limb of the loop of Henle?

A

Water

28
Q

How does the collecting duct vary its water permeability?

A

Inserting or removing aquaporins

29
Q

How is HCO3 exchange at the baso-lateral membrane different in the thick ascending limb to the proximal tubule?

A

In the TAL it is coupled with Cl whereas in the proximal tubule it is coupled with Na

30
Q

What mediator regulates Na reabsorption in the collecting duct?

A

Aldosterone

31
Q

What is the myoenteric reflex?

A

Swelling of the afferent arteriole is sensed mechanically and the it constricts in response

32
Q

What transport occurs at the distal tubule?

A

Transcellular co-transport of Na with Cl

33
Q

Describe Na transport in the proximal tubule

A

Na/K pumps on the baso-lateral membrane creates a Na gradient into the epithelials. Na is coupled with other solutes and co-transported across the apical membrane.

Some Na backleaks through the paracellular path back into the lumen

34
Q

What is the filtration rate of plasma?

A

180L per day

34
Q

What pressure is the glomerulus kept at ideally?

A

50mmHg

34
Q

What is the major O2 consumer in the kidneys?

A

Na/K ATPase

35
Q

What is the target of frusemide?

A

Na/K/Cl co-transporters in the thick ascending limb

36
Q

What are the implications of the high flow of water out of the lumen in the proximal tubule?

A

It takes solutes that are disolved in it with it, like K, Ca and urea

38
Q

What factors influence GFR in the glomerulus?

A

Hydrostatic pressure in the glomerulo-capillaries

Hydrostatic pressure in the bowmen’s capsule

Onsotic pressure in the glomerulo-capillaries

Oncotic pressure in bowmen’s capsule

40
Q

Why does the filtration rate decrease along the glomerulo capillary?

A

Oncotic pressure increases in the capillary

41
Q

What does the macula densa do?

A

Senses the Na+ in the thick ascending tubule annd produces mediators that control the tone of the afferent arteriole

42
Q

What is the maximum and minimum concentration that urine can be excreted at?

A

1200 miliosmols

30 miliosmols

43
Q

How is phosphate reabsorbed?

A

Co-transported with Na in the apical membrane of the proximal tubule

44
Q

How is Na transported in the thick ascending loop of Henle?

A

Active transport

46
Q

T/F Each nephron has it’s own collecting duct

A

False, multiple distal tubules drain into a single collecting duct

46
Q

What do efferent arterioles become?

A

Peritubular capillaries

47
Q

How are amino acids reabsorbed?

A

Co-transported with Na in the apical membrane of the proximal tubule. 7 different types of co-transporters

48
Q

Is Cl transport in the proximal tubule transcellular or paracellular?

A

Paracellular

50
Q

What happens to GFR when the afferent arteriole constricts?

A

It decreases

51
Q

Which arteriole does angiotensin II constrict more?

A

The efferent

52
Q

Describe the sequential segments of the nephron

A

Bowmen’s capsule

Proximal tubule

Thin descending loop of Henle

Thin ascending loop of Henle

Thick ascending loop of Henle

Distal tubule

Collecting duct

52
Q

What are the 2 parts of the proximal tubule?

A

Proximal convoluted tubule

Pars recta

53
Q

How is glucose reabsorbed?

A

Co-transported with Na in the apical membrane of the proximal tubule

55
Q

How can renal failure cause anaemia?

A

Loss of EPO production

56
Q

What endocrine signals does the kidney produce?

A

EPO, renin, Vitamin D3, PGI2 (aka prostacyclin)

57
Q

What is the effect of renin release?

A

Increase blood volume

Na conservation

58
Q

What happens to K in the collecting duct?

A

It’s secreted

59
Q

Why can’t most plasma proteins filter through the capillaries?

A

They are negatively charged and so it the lamina propria

61
Q

Why do the capillaries have fenestration?

A

Limits the size of what can be filtered through

62
Q

Where in the proximal tubule is more HCO3 reabsorbed?

A

Early on in the PT

64
Q

How much phosphate is excreted?

A

20%

66
Q

What happens to GFR when efferent arteriole constricts?

A

It increases

67
Q

At what rate is GFR problematic?

A

30-40L per day

69
Q

What is the mediator of arteriole constriction released by the macula densa?

A

Adenosine

Thromboxane

71
Q

What is the renal blood flow rate?

A

1L per minute (in a 70kg adult)

73
Q

How Ca reabsorption regulated?

A

Parathyroid in the proximal tubule

Vitamin D3 in the distal tubule

74
Q

How is urea reabsorbed?

A

Passive means

75
Q

How does the ECF concentration vary across the kidney?

A

300mOsmol at the cortex

1200mOsmol towards the papilla

76
Q

What percentage of K is excreted?

A

10%

77
Q

What is the filtration fraction of the kidneys?

A

20%

78
Q

What percentage of urea is excreted?

A

50%

79
Q

What are the functions of the kidneys?

A

Water and Na homeostasis

Control of ECF ion concentration (K+, Cl-, Ca++, Mg++, HPO4-2)

Acid-base control

Excretion of waste products and xenobiotics

Endocrine functions

Formation or concentrated/diluted urine

80
Q

Which type of glomeruli are there more of?

A

Superficial cortical glomeruli

81
Q

What must happen to calciferol?

A

Have 2 hydroxy groups added

82
Q

How is water reabsorbed in the proximal tubule?

A

Passive transport transcellularly and paracellularly, following the gradient created by Na transport

83
Q

What normally happens to GFR when MAP increases from 90 to 110?

A

It doesn’t change