Renal Flashcards

1
Q

Urinary excretion rate =

A

Urinary excretion rate = Filtration rate - (Reabsorption rate + Secretion rate)

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2
Q

Creatinine in kidneys

A

Are only filtered not reabsorbed nor excreted

Filtration = Excretio

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3
Q

Na, Cl ions and others are

A

Freely filtered and partially reabsorbed

Excretion = Rate of filtration - Rate of reabsorption

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4
Q

Amino acids and glucose

A

Freely filtered and completely reabsorbed from tubules

No excretion

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5
Q

Organic acids and bases

A

Freely filtered not reabsorbed but additional substances secreted from capillary to tubule

Excretion rate = Filtration + secretion rate

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6
Q

Filtration fraction =

A

Filtration fraction = GFR/Renal plasma flow

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7
Q

The GC has 3 layers

A

1 endothelium
2 basement membrane
3 epithelial cell podocyte

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8
Q

Normal GFR

A

125 ml/min 180L/day

Filtrate devoid of protein, rbc, half of Ca bound and fatty acid

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9
Q

Fenestrations in gc are endowed with

that hinder passage of plasma proteins

A

negative charges

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10
Q

Filterability of solutes are determined by

A

Size

Electrical charge

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11
Q

Proteinuria/Albuminuria occurs in minimal change disease bec of

A

loss of negative charge on the basement membrane proteoglycan

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12
Q

Net filtration pressure =

A

Net Filtration Pressure = (GCh - Bh) - (GCc+Bc)

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13
Q

Glomerular Filtration Rate =

A

Glomerular Filtration Rate =

Kf x (Net filtration pressure)

Kf x [(GCh-Bh)-(GCc+Bc)]

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14
Q

Kf normal

A

12.5 ml/min/mmHg

Kf = GFR/NFP
Kf = 125/10mmHg
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15
Q

DM alters Kf by

A

Inc thickness of bm and damaging functional capillary less surface area

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16
Q

In obstructive renal disease such as calcium or uric stones, GFR is markedly dec bec of

A

Inc Bowman capsule hydrostatic pressure from backflow limiting filtration

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17
Q

Inc glomerular capillar colloid osmotic pressure : GFR

A

Decreases GFR

BY:
Inc arterial plasma colloid osmotic pressure, inc glomerular capillary colloid osmotic and dec GFR
Inc filtration fraction concentrating plasma proteins, inc colloid osmotic, dec GFR

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18
Q

A greater rate of blood floe into glomerulus: GFR

Lower rate of blood flow into glomerulus: GFR

A

Increases

Decreases

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19
Q

Primary means of physiologic regulation of GFR

A

Glomerular hydrostatic pressure

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20
Q

Glomerular hydrostatic pressure is determined by (3)

A

1 arterial pressure (inc AP, inc GFR)
2 afferent arteriole (vasoconstriction dec GFR and vice versa)
3 efferent arteriole (vasoconstriction inc GFR slightly as long as the inc does not reduce renal blood flow)

too much efferent vasoconstriction eventually dec GFR bec dec renal blood flow can promote inc filtration fraction and inc colloid osmotic pressure DEC GFR)

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21
Q

Oxygen consumption of kidney is related to

A

High rate of active sodium reabsorption by tubule

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22
Q

Renal blood flow =

A

Renal blood flow =

(Renal artery pressure1 - Renal vein pressure2)/Total renal vascular resistance

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23
Q

Total renal vascular resistance come from

A

Interlobular arteries
Afferent arteriole
Efferent arteriole

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24
Q

Strong activation of renal sympathetic nerves and autacoids (NE, Epi, Endothelin) such as in defense rx, ischemia brain, or severe hemorrhage

A

Dec GFR

Otherwise in mild to mod vasoconstriction, little influence on blood flow

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25
Q

Angiotensin II acts preferentially on the efferent arteriole when activated to

A

Promote flow in the glomerulus
Prevent dec glomerular hydrostatic pressure and prevent dec GFR
Efferent constriction causes reduction in renal blood flow leading to dec flow in peritubular capillaries and sodium and water reabsorption increases

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26
Q

Autoregulation of kidneys depend on:

A

1 sodium chloride concentration at macula densa

2 control of renal arteriolar resistance

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27
Q

GFR autoregulation is accomplished by

A

1 renal autoregulation

2 glomerulotubular balance (adaptive mech in renal tubules)

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28
Q

Tubuloglomerular feedback components:

A

1 afferent arteriolar feedback
2 efferent arteriolar feedback

depending on juxtaglomerular complex

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29
Q

JGC components

A

1 macula densa (initial distal tubule)

2 juxtaglomerular cell (afferent and efferent)

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30
Q

Macula densa cells sense change in volume delivery at distal tubule when

A

Dec GFR slows flow rate at LOH
INC reabsorption of NaCl ions in ascending LOH
Dec concentration of NaCl at macula densa

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31
Q

Dec of NaCl at macula densa cause:

A

Dec resistance to blood flow in afferent arteriole Inc GFR

Inc renin release in JGC (RAAS)

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32
Q

Angiotensin II inc GFR by

A

Vasoconstricting afferent arterioles

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33
Q

Myogenic mechanisms in renal arteriole has important protective function against

A

Hypertension-induced kidney i

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34
Q

Filtration =

A

Filtration = Glomerular filtration x Plasma conc

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35
Q

Reabsorption across tubular epi into interstitial fluid occurs by

A

active or passive transport

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36
Q

Transport from interstitial fluid into peritubular capillary involve

A

ultrafiltration (bulkflow)

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37
Q

Moves solute against electrochemical gradient requires energy from metabolism

A

active transport

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38
Q

Transport coupled to an energy source such as hydrolysis of ATP is called

A

Primary Active Transport

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39
Q

Transport coupled indirectly to energy source such as ion gradient

A

Secondary active transport

ex glucose

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40
Q

Diffusiob from a region of low solute to high solute concentration

A

Diffusio

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41
Q

Primary active transport in kidneys (4)

A

Na/K
H ATPase
H/K
Ca ATPase

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42
Q

Na enters apical membrane from tubular lumen by

A

Electrochemical gradient established by NaK ATPase

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43
Q

Na is transported across basolateral membrane by

A

Electrochemical gradient by NaK ATPase

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44
Q

Na is reabsorbed from interstitial fluid into peritubular capillary by

A

Ultrafiltration

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45
Q

Reabsorption or secretion of solutes across cells

A

Transcellular

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46
Q

Transport of solutes between cells across tight junctions and intercellular spaces

A

Paracellular

47
Q

Located on brushborder of proximal tubular cells carry glucose into cytoplasm against concentration gradient

A

Na-glucose co transporter SGLT2 (90%) and SGLT1

48
Q

Glucose diffuses out into interstitial space with help

A

GLUT1 and GLUT2

49
Q

Substances are secreted into tubules by secondary transport

Ex. Sodium reab in luminal membrane coupled with H extrusion from cell by Na-H

A

Countertransport

Na H exhanger

50
Q

Amount of solute delivered to tubuke exceeds capacity of carrier proteins and specific enzymes involved in transport

A

Transport maximum

51
Q

Appearance of glucose in urine occurs before transport max is reached

A

Glucose threshold

52
Q

Overall transport maximum 375mg/min is reached when

A

All nephrons have exceeded maximal capacity to reabsorb

53
Q

When rate of transport is determined by electrochemical gradient for diffusion, permeability of membrane for substance and time that the substance remains within tubule

A

Gradient-time transport

54
Q

PCT Reabsorption and transport

A

65% water, Na, Cl, bicarbonate, K, glucose and AA

NaCl Na/K ATPase
Na-Glucose and Na-AA co transport
Na-H exchange

55
Q

H secretion to lumen of PCT is important for

A

Removal of bicarb

56
Q

First half of proximal tubule reabsorption

A

Co transport with Na, glucose, AA, bicarbonate

57
Q

Second half of PCT

A

Na with Cl

58
Q

Organic solute that remains highly concentrated at PCT

A

Creatinine

59
Q

Total solute conc and osmolarity remains the same along PCT bec

A

It is extremely permeable to water

60
Q

PCT excretes

A

Bile salt oxalate urate and catecholamine

61
Q

Used to estimate renal plasma flow bec of rapid secretion in PCT

A

PAH Para-aminohippuric acid

62
Q

Filters 20% of water and allows simple diffusion

A

Thin descending limb of LOH

63
Q

Impermeable to water

bec

A

Thick and thin ascending limb of LOH

concentration of urine

64
Q

The thick ascending limb reabsorbs

A

25% of Na, Cl, K, Ca, bicarb, magnesium

65
Q

Transporter in the thick ascending limb of LOH mediating Na transport

A

NaK2Cl co transporter

66
Q

Site of action of furosemide, ethacrynic acid and bumetanide

A

Thick ascending limb of LOH

67
Q

Thick ascending limb also has

Apart from NaK2Cl

A

Na-H counter transport

68
Q

Paracellular reabsorption of Ca, Mg, Na and K in thick ascending limb occurs bec of

A

Slight + charge of lumen with slight backleak of K into lumen creating + charge of 8mv

This forces cations to diffuse from lumen to paracellular space

69
Q

First portion of distal tubule:

A

Reabsorbs 5% of NaCl

Contains distal tubule from macula densa of JGC

70
Q

Second portion of the DCT reabsorbs most ions but impermeable to water bec

A

It acts as diluting segment

71
Q

Transporters in the DCT

A

Na-Cl co transporter

Cl channels

72
Q

Site of action of thiazide diuretics

A

DCT

73
Q

Thiazide inhibit

A

Na-Cl co transporter

74
Q

Cell types of late distal and cortical collecting tubule

A

1 principal cell

2 intercalated cell

75
Q

Reabsorb sodium and water and secrete K into lumen

A

Principal cell

76
Q

Reabsorb K and secrete H ion into lumen

A

Intercalated cell

77
Q

Principal cells are sites of action of

A
K sparing diuretics
Spironolactone
Eplerenone
Amiloride
Triamterene
78
Q

Mineralocorticoid antagonist that compete with aldosterone for receptor sites at principal cells

A

Spironolactone
Eplerenone

Inhibit sodium reabsorption and K SECretion hence sparing

79
Q

Sodium channel blockers that directly inhibit entry of sodium and reduce transport of K secretion into cells

A

Amiloride

Triamterene

80
Q

H ion secretion in the intercalated cell is mediated by

A

H ATPase transporter

Capable of secreting H ions against a large conc gradient 1000:1

Key role in acid base

81
Q

For each H ion secreted,

A

a bicarbonate ion becomes available for reabsorption across basolateral membrane

82
Q

Site of action of aldosterone

A

Late distal tubule

Cortical collecting tubule

83
Q

Site of action of ADH

A

Late distal tubule
Cortical collecting duct
Medullary CD

84
Q

ADH/Vasopressin MOA

A

makes the late distal tubule and cortical collecting duct permeable to water

85
Q

Final site processing of urine and plays important role in determining final urine output

Reabsorbs

A

Medullary Collecting Duct

<10% of water and sodium

86
Q

Unique to medullary collecting duct are

A

Urea transporters that permit urea reabsorption

87
Q

Urea reabsorption in MCD helps

A

Raise osmolality forming concentrated urine

88
Q

MCD also secretes

A

H ions

89
Q

Polysaccharide used to measure GFR not reabsorbed nor secreted
Reflect changes in water present in tubule

A

Inulin

90
Q

Total rate of reabsorption increases as filter load increases despite constant GFR in PCT at 65%

A

Glomerulotubular balance

91
Q

Inc arterial pressure effect on

peritubular capillary hydrostatic pressure

reabsorption rate

A

inc hydrostatic pressure

dec reabsorption rate

92
Q

inc in resistance of afferent or efferent arteriole effect on

pretubular capillary hydrostatic pressure

reabsorption rate

A

Dec hydrostatic pressure

Inc reabsorption rate

93
Q

Inc in arterial pressure causes pressure natriuresis bec (3)

A

Impaired autoregulation
Inc hydrostatic pressure of renal interstitial fluid causing Na backleak to lumen
Reduced angiotensin II

94
Q

Aldosterone

Site of action

Effect

A

Collecting tubule and duct

Inc NaCl and water reabsorption
Inc K SECRETION

95
Q

Important regulator of K

A

Aldosterone

96
Q

Angiotensin II site

Effects

A

PCT, TAL of LOH, DCT AND CT

1 Inc Aldosterone secretion - Inc NaCl and water reabsorption
2Constriction of efferent arterioles - inc peritubular capillary reabsorption and inc filtration fraction to inc colloid osmotic pressure in peritubular capillary all leading to inc reabsorption
3 Inc H secretion
4 Direct stimulation of Na reabsorption in PCT, LOH, DCT and CT

97
Q

Angiotensin II exerts direct effect on transporters

A

Na-H exchange NHE
Na/K ATPase
Na-HCO3 co transport

98
Q

ADH site of action

Effect

A

DCT, CT, CD

Inc water reabsorption

99
Q

ADH binds to what receptor in the DCT, CT and CD

A

V2 receptor

100
Q

ADH MOA

A

V2 receptor binding coupled with Gs activating adenylate cyclase
Inc cAMP and activation of Protein Kinase
Movement of AQP2 on luminal side of cell
Exocytosis forms water channels permiting rapid diffusion of water through cells

101
Q

Plasma volume expansion leading to cardiac atria distention stimulate release of

A

Atrial natriuretic peptide

102
Q

ANP site

Effect

A

DCT, CT and CD

Dec NaCl reabsorption

103
Q

PTH site

Effect

A

PCT, TAL of LOH, DCT

Dec phosphate reabsorption
Inc Ca reabsorption

104
Q

Sympthetic effect on Na reabsorption

A

Constriction of renal arteriole leads to dec GFR from dec Na and water excretion
Inc renin and Angiotensin II formation

105
Q

Renal clearance =

A

Renal clearance = Volume of plasma completely cleared of substance by kidney/unit time

106
Q

Clearance rate of a substance =

A

Cs = (urine concentration x urine flow rate)/plasma concentration

Cs = urinary excretion rate (U x V) / plasmac

107
Q

GFR =

A

GFR = (urine concentration of substance x urine flow rate)/plasma concentration of substance

108
Q

Susbtances used to measure GFR (3)

A

Inulin
Creatinine
Radioactive iothalamate

109
Q

Creatinine clearance isn’t perfect marker of GFR because

A

Small amount is secreted by tubules

so amount excreted slightly exceeds the amount filtered

Overestimation of GFR

110
Q

Used to estimate renal plasma flow bec of its 90% clearance from plasma

A

Para-ammino hippuric acid

111
Q

Filtration fraction=

A

Fraction of plasma that filters through glomerular membrane

FF = GFR/RPF

112
Q

Causes of K shift into cell

A

Insulin
Beta adrenergic agonist
Alkalosis (H-K exchange)
Hypoosmolarity

113
Q

Causes of K shift out/Hyperkalemia

A
Insulin deficiency
Beta adrenergic antagonist
Acidosis
Hyperosmolarity
Inhibitors of Na-K pump eg digitalis
Exercise
Lysis