Renal Physiology Flashcards

1
Q

Normal pH of Kidneys

A

7.4 by regulating H+ and HCO3-

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2
Q

Positive Balance

A

Intake exceeds output

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3
Q

Negative Balance

A

Output exceeds input

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4
Q

Weight of both kidneys

A

300 grams of <0.5% body weight

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5
Q

How many nephrons in adult Kidney?

A

1.2 million… can life active life with only 25% of these

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6
Q

Superficial Nephrons

A

short loop of Henle
efferent arteriole gives rise to peritubular capillaries
no thin ascending limb

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7
Q

Juxtamedullary Nephrons

A

long loop of Henle
Thin ascending limb
Efferent arteriole gives rise to peritubular capillaries AND ascending vasa recta

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8
Q

Proximal Tubule

A

Brush border on apical side, highly invaginated basolateral membrane filled with mitochandria

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9
Q

Straight portion of Proximal Tubule (pars recta)

A

much less well endowed with basolateral infoldings and mitochandria

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10
Q

Thin descending and thin ascending loop of Henle

A

poorly developed apical and basolateral membranes and few mitochandria

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11
Q

Thick ascending Limb of Henle and Distal Tubule

A

Extensive basolateral infoldings with mitochondria

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12
Q

Collecting Duct

A

Principle cells and Intercalated cells

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13
Q

Principle cells

A

Moderately invaginated basolateral membrane with few mitochondria.
Important for Na and Cl reabsorption

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14
Q

Intercalated Cells

A

Have high density of mitochondria
One population secretes H+
The other secretes HCO3-

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15
Q

Renal Blood flow

A

25% of cardiac output

5L/min and 25%= 1250ml/min-1ml/min=1249ml/min

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16
Q

Urinary Flow Rate (V)

A

1 ml/min

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17
Q

Renal Plasma Flow

A

Renal Blood Flow (RBF) x (1-hematocrit)

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18
Q

Water

A

180L/day filtered

42L in human

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19
Q

Sodium

A

25,000 mEq/day filtered

3,000 mEq in human

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20
Q

3rd space

A

Part of ECW including peritonea, synovial, pleural, cerebral spinal fluids, saliva.
Increase in 3rd space with ascites

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21
Q

Plasma

A

92& water
7% protein
1% small solutes

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22
Q

ECW

ICW

A

Na, Cl, HCO3-

K, organic phosphate and protein

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23
Q

Volume (equation)

A

Volume= amount/concentration

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24
Q

Osmolality

A

The concentration of discrete osmotically active particles in solution
Function of # particles regardless of mass, charge, size

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25
Q

Which has higher osmolality, interstitium or plasma?

A

Plasma bc of higher protein concentration

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26
Q

Generalized Edema

A

Both ICFV and ECFV expand
Osmolality falls
Gain of isoosmotic/isotonic NaCl
Add Pure water

Decreased excretion by kidneys of Na and Cl

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27
Q

Severe Diarrhea

A

Only ECFV expands
No change in osmolality
Loss of isosmotic/isotonic NaCl
Add isotonic NaCl

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28
Q

Hot Desert/Sweating

A

ICFV shrinks, ECFV expands
Loss of Pure water or hypotonic NaCl
Add Pure NaCl

29
Q

GFR (equation)

A

Ccr= Ucr x V
———
Pcr

30
Q

Plasma Ultra Filtrate
Systemic
Glomerular

A

Systemic- declines bc hydrostatic pressure falls

Glom- declines bc oncontic pressure rises

31
Q

Filtration Fraction

A

GFR/RBF= 0.2 (20% filtered)

32
Q

Any change in Efferent Arteriole Resistance results in what?

A

A change in the Fractional Filtration (FF)

33
Q

Where is Renin made?

A

Juxtaglomerular Apparatus

34
Q

Juxtaglomerular Apparatus

A
  1. Macula Densa Cells (thick ascending)
  2. Renin producing Granular Cells (afferent arteriole)
  3. Extraglomerular Mesangial Cells
35
Q

Factors that Inc/Dec Renin secretion

A
Nerve stimulation (NE/E) (cAMP)
Renal vascular baroreceptors (Ca)
Prostaglandins (cAMP)
Macula Densa Mechanism (dec distal Na)
ANGIOTENSIN II = inhibits renin secretion (feedback)
36
Q

Prostaglandins

A

Increase bc of vasoconstrictors and cause vasodilation of the afferent and efferent arterioles

37
Q

Nitric Oxide

A

Vasodilator
Sensitive to arganine analogs
NO increases with shear stress, bradykines, ACh, ATP

38
Q

Trancellular Reabsorption

A

Across the apical membrane the cytoplasm and the basolateral membrane

39
Q

Paracellular Reabsorption

A

Between renal tubular cells across the tight junction and thru the lateral intercellular space

40
Q

If glucose exceeds the renal threshold above which TM is exceeded

A

Glucosuria

Uncontrolled Diabete

41
Q

If glucosuria is observed even when plasma glucose is below renal threshold

A

GFR is extremely high –> Pregnancy

Transporters are impaired–> Genetic mutation or proximal tubule damage

42
Q

Which electrolyte is similar to glucose?

A

Phosphate

43
Q

What is urea reabsorption dependent on?

A

Flow

44
Q

Describe the mechanism of urea

A

The flow rate decreases as water is reabsorbed from lumen in to interstitial. Consequently, urea becomes more concentrated in tubular lumen and then gets reabsorbed down its chemical gradient in to the interstitium

45
Q

Amount Reabsorbed (equation)

A

GFR x Pgluc x Ugluc x V= amt reabsorbed

46
Q

Amount Secreted (equation)

A

Ux x V - GFR x Px

47
Q

PAH

A

Para-aminohippurate
TMpah= 80mg/ml
90% is not bound to proteins aka freely filtered
Undergoes secretion in proximal tubule by secondary transport

48
Q

Sodium Reabsorption in Early Proximal Tubule

A
Na-H antiporter
Na-glucose symporter--> electrogenic
Na-amino acid symporter
Na-lactate symporter
3Na-phosphate antiporter
49
Q

Sodium Reabsorption in Late Proximal Tubule

A
Na-H antiporter
Cl-anion antiporter
Passive diffusion of Cl through paracellular--> results in positive potential difference therefore drives passive Na reabsorption
50% of NaCl reabsorption here
2Na-glucose symporter
50
Q

How much water, Na and Cl does the proximal tubule reabsorb?

A

67%
2/3 trancellular
1/3 paracellular
Reabsorbs all of glucose, amino acids, HCO3, lactate

51
Q

Is the proximal tubule hyperosmotic or isosmotic?

A

slightly hyper osmotic but wesay that it’s isosmotic bc water is highly permeable here

52
Q

An increase in oncotic pressure or decrease in hydrostatic pressure in PTC will promote what?

A

Water reabsorption

53
Q

What stimulates sodium reabsorption in proximal tubule?

A

Angiotensin II and catecholamines

54
Q

What inhibits sodium reabsorption in proximal tubule?

A

Nitric oxide

Atrial natriuretic factor

55
Q

Ouabain

A

Na-K ATPase inhibitor

56
Q

Acetozolamide (diamox)

A

Carbonic anhydrase inhibitor

57
Q

Mannitol

A

Osmotic diuretic

58
Q

Sodium Reabsorption in Loop of Henle

A

25% sodium reabsorbed

15% water (only thin descending)

59
Q

Thick ascending limb of Henle

A

Na-K-2Cl symporter

60
Q

Furosemide (lasix)

A

inhibits the Na-K-2Cl symporter

aka unreabsorbed solutes

61
Q

Proximal Tubule and Thick ascending limb of Henle Diuretics

A

67% and 20% of filtered potassium is usually reabsorbed so profound potassium wasting with these drugs

62
Q

Early Distal Tubule

A

Na-Cl symporter in apical membrane
Thiazide diuretics block this
Impermeable to water

63
Q

Late Distal Tubule and Collecting Duct

A

Reabsorb NaCl and Water
Na channel in apical membrane
Ameloride and Triamterene- Inhibit this channel
Potassium sparing diuretics

64
Q

What is the major factor that stimulates Na reabsorption in the distal tubule and collecting duct?

A

Aldosterone

Secreted by adrenal cortex (in response to angII or increase plasma K)

65
Q

Within minutes of stimulation…

A

Aldosterone increases reabsorption
Increases protease activity
Inserts more Na/K-ATPase in basolateral membrane

66
Q

Within several hours…

A

Increase gene expression of Na-K-ATPase and Na-Cl symporter

67
Q

Spironolactone

A

Potassium sparing diuretic

Binds to mineralocorticoid receptor

68
Q

Atrial natriuretic and Brain Natriuretic Peptides inhibit what?

A

NaCl and water reabsorption by medullary collecting duct