Renal Function Flashcards

1
Q

List the 3 things that compose the Glomerular Filtration Barrier

A

1) Capillary Endothelium
2) Glomerular Basement Membrane
3) Podocyte Epithelium

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2
Q

Molecules < ___ A are freely filtered

A

20

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3
Q

Molecules > ___ A are not filtered

A

42

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4
Q

Lammina Rara Externa is exposed to the ____

A

Bowmans Capsule

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5
Q

Lamina Rara Interna Is exposed to ___

A

Blood

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6
Q

Describe what the Lamina Rara Interna and Lamina Rara Externa are composed of and how it contributes to the charge of the GBM.

A

1) Proteoglycans, Predominately Heparin Sulfate
2) Have electronegative charge

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7
Q

How does the Glycocalyx contribute to the charge of the GBM?

A

Provides a negative charge

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8
Q

Concentrations are ___ on both sides of the GBM

A

Equal

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9
Q

How do you calculate Urinary Excretion

A

Amount Filtered - Amount reabsorbed + Amount Secreted

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10
Q

How do you calculate Tubular Reabsorption?

A

Glomerular Filtration - Urinary Excretion + Amount Secreted

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11
Q

If excretion > filtration, then ____ must have occurred

A

Tubular secretion

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12
Q

In terms of the Kidney, Arterial input must equal ____ + ____

A

1) Venous Output
2) Urine Output

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13
Q

How do you calculate urinary concentration of X (Ux)?

A

Ux = Concentration/Volume

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14
Q

Define Urinary Concentration

A

Concentration of that substance in the urine in a given volume

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15
Q

How do you calcular Urine Flow Rate?

A

V = Urine volume/ time

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16
Q

How do you calculate urine excretion rate?

A

Ux * V

Urinary Concentration multiplied by the Urine Flow Rate

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17
Q

Urine excretion rate is directly porp. to ___ and __

A

Urine Concentration and Urine Flow Rate

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18
Q

Clearance is a ____ rate

A

Flow

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19
Q

Define Renal Clearance

A

Volume of plasma completely cleared of a substance by the kidneys per unit time

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20
Q

Renal Clearance is the ratio of:::

A

urinary Excretion (Ux * V) to Plasma Concentration (Px)

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21
Q

What are the units for Renal Clearance and what does it mean?

A

1) Volume per unit time
2) Volume of plasma cleared of the substance per unit time

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22
Q

What is the Equation of Renal Clearance of a Substance

A

Cx = Ux * V/ Px

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23
Q

Define Glomular Filtrate (GF)

A

The fluid filtered across the glomerular capillaries into Bowns Space

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24
Q

____ = Volume of plasma filtered into the combined nephrons of both kidneys per unit of time (mL/min)

A

Glomerular Filtration Rate (GFR)

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25
Q

How do you calculate Capillary filtration coefficient (Kf)

A

Permeability * Surface Area

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26
Q

What is the normal Filtration Frcation?

A

20%

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27
Q

How do you calculate Filtration Fraction?

A

FF = GFR/RBF

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28
Q

What does the Filtration Fraction represent?

A

Fraction of RBF that is filtered across the Glomerulus and reaches the tubules

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29
Q

How will an increased of ultrafiltration pressue influence FF?

A

Increase

FF = GFR/RBF; so as Ultrafiltration pressure increases GFR will increase leading to an increase in FF.

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30
Q

How does an increase of RBF influence FF?

A

Decreases

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31
Q

Conceptually why does efferent arteriole oncotic pressure increase wjem FF increases?

A

Increased fluid will be filtered leaving increased protein in the arterioles. This leads to an increase of oncotic pressure in the efferent arteriole.

32
Q

With a decreased filtration fraction the oncotic pressure in the efferent arteriole will ____

A

Decrease

33
Q

How is Filtered Load different from Filtration Fraction. How do you calculate both?

A

1) Filtered Load is about a specific substance, at which it is getting filtered. To calculate Filtered Load, Multiply GFR with Plasma Conc. of that substance
2) Filtration Fraction is the ratio of GFR to RBF. The Equation is FF= GFR/RBF

34
Q

You can use ___ to estimate GFR

A

Renal Clearance

35
Q

What is normal GFR

A

125 mL/min

36
Q

GFR is directly proportional to renal clearance if:

A

1) Substance must be freely filterable in the glomeruli
2) Substance must be neither reabsorberd nor secreted by the renal tubules
3) Substances must not be synthesized, broker down, or accumulated by the kidney
4) Substances must be physiological inert (not toxic and without effect on renal function)

37
Q

What is the equation for renal clearance

A

Cx = Ux * V/ Px

38
Q

You can calculate GFR by measuring Clearance for which twoo molecules?

A

Creatinine

Inulin

39
Q

Systemic Sympathetic Stimulation actives Local renal sympatheic nerves. What does this activation lead to?

A

1) Constriction of renal arterioldes (decreases GFR)
2) Increases Tubular Reabsorption of Water and Salt
3) Activates RAAS (further increases tubular reabsorption)

40
Q

There are greater number of alpha 1 receptors on ____ vs ___ arterioles. This leads to a powerful constriction upon sympathetic stimulation.

A

1) Afferent
2) Efferent

41
Q

Other than RAAS how does sympathtics increase tubular reabsorption of water and salt?

A

Na-K ATPase via alpha 1 receptor

42
Q

What type of receptor simulates Renin release and activation of RAAS?

A

B1

43
Q

What are the three physical factors that contribute to GFR

A

1) Hydraulic Conductivity (Lp)
2) Surface area for filtration (Sf)
3) Capillary Ultrafiltration Pressure (Puf)

44
Q

How do you calculate GFR when taking in consideration of Hydraulic Conductivity, Surface Area for Filtration, and Capillary Ultrafiltration Pressure?

A

GFR = Kf * Puf

Kf = Ultrafiltration Constant; Product of Surface area * Hydraulic Conductivity

45
Q

Define Hydraulic conductivity

A

Permeability/porosity of the fenestrated endothelium

46
Q

How do you calculate Puf?

A

Ultrafiltration Pressure = Pgc - Pbc - piegc

47
Q

How does an increase in ultrafiltration coefficient affect the GFR?

A

Increases GFR

48
Q

How does an increase in Ultrafiltrate Pressure effect GFR?

A

Increases

49
Q

Ultrafiltrate coefficient and Ultrafiltrate Pressure are (Inversely/directly) Porp. to GFR?

A

Directly

50
Q

What is the main variable that can change Puf.

A

Pgc

51
Q

Describe what determines Pgc. (3x)

A

1) Renal arterial blood pressure
2) Afferent arteriolar resistance
3) Efferent arteriolar resistance

52
Q

What influences Kf (Ultrafiltration Coefficient)

A

1) Surface Area
2) Permeability

53
Q

What role do glomerular mesangial cells play in influencing Sf?

A

1) Decrease Sf when contract
2) Increase Sf when relaxed

54
Q

How does Constriction and Dilation of Afferent Arteriole affect: Puf, GFR, RBF, and Pgc

A

1) Constriction:
- Puf: Decreases
- GFR: Decrease
- RBF: Decrease
- Pgc: Decreases
2) Dilation
- Puf: Increase
- GFR: Increase
- RBF: Increase
- Pgc: Increase

55
Q

How does Constriction and Dilation of Efferent Arteriole affect: Puf, GFR, RBF, and Pgc

A

1) Constriction
- Puf: Increase
- GFR: Increase
- RBF: Decrease
- Pgc: Increase
2) Dilation
- Puf: Decrease
- RBF: Increase
- GFR: Decrease
- Pgc: Decrease

56
Q

List molecules that cause renal vasoconstriction. ?(4x)

A

1) Sympathetics (Catecholamines)
2) Endothelin
3) ATP/adenosine
4) Angiotensin II

57
Q

List molecules that cause renal vasodilation (6x)

A

1) Prostagladins
2) Bradykinin
3) Nitric oxide
4) Dopamine
5) Atrial Natriuretic Peptide
6) ACE-Inhibitor

58
Q

What molecule primarily constrics efferent arterioles? What does this lead to interms of GFR and RBF?

A

Angiotensin II

Increased GFR

Decreased RBF

59
Q

Sympathetics and Catecholamines affect which more: Efferents or Afferents? Why?

A

Afferents due to increased alpha 1 receptors

60
Q

What does Increasing GFR do to PTC?

A

1) Increases PTC oncotic Pressure
2) More stuff dumped into PT

*** Both of these result in increased reabsorption rates in the tubules!!!

61
Q

Periods of High Blood Pressure in the kidneys leads to local myogenic feedback reflex. Describe this reflex.

A

1) Results in Afferent Arteriolar Constriction
2) Results in Efferent Arteriolar Dialtion

62
Q

Describe Function of Tubuloglomerular Feedback

A

Maintains constanat Na+ delivery to the distal tubule and constant GFR

63
Q

In tubuloglomerular feed back, macula densa cells are communicating with ____ cells

A

JG

64
Q

What is apart of the Juxtaglomerular Apparatus

A

1) Macula Densa Cells
2) Juxtaglomerular (Granular) Cells
- Renin
3) Extraglomerular Mesangial (Iacis) Cells

65
Q

Describe what occurs when their is increased NaCl delivery to macula densa.

A

1) Increased Na+ reabsorbed via NKCC2
2) More ATP/adenosine is released
3) Calcium is released to vascular smooth muscle cells surrounding afferent arteriole
4) Afferent arteriole constricts
5) Decreased GFR and Decreased Renin release

66
Q

Describe what occrs when the macula densa senses that there is decreased NaCl

A

1) Decreased reabsorbed via NKCC2
2) :Less ATP/adenosine is released
3) Calcium not released in vascular smooth muscle cells
4) Afferent Arteriole Relaxes
5) Increases GFR
6) Increased Renin released

67
Q

What promotes Renin Secretion?

A

1) Decreased NaCl delivery to Macula Densa
2) Renal Sympathetic Stimulation via B1 receptor activation in JG apparatus

68
Q

How can macula densa dialate afferent arteriole

A

Via NO

69
Q

List the actions of Angiotensin II

A

1) Promotes Aldosterone Secretion
2) Vasoconstrict Efferents Arteriole
3) Enhances TGF
4) Stimulates thirst and ADH release

70
Q

Integrated Response to decreased ECV: Sympathetics

A

1) increases renal vascular resistance
2) Increased Na+ reabsorption
3) Enhances renin release (indirectly)

71
Q

What is the major factor in controlling ADH response?

A

Osmolarity

72
Q

The main purpose of Autoregulation and Tubuloglomerular feed back is to _______

A

Protext the glomerulus and stabilize GFR

73
Q

The main purpose for extrinsic renal hemodynamics: Sympathetic nerves, hormones, and composition of blood is to __________

A

Correct body fluid disturbances and stabilize blood pressure

74
Q

What is the equation for Fractional Excretion. What is the equation when using it for creatinine?

A

FEx = Amount of X excreted/ Amount of X Filtered

= Ux * V/ Px * GFR

= Uc * Pcr/ Px * Ucr

75
Q

Describe Fractional Excretion

A

Percentage of whatever has beem filtered actually gets excreted

76
Q
A