Brainscape's Knowledge GenomeTM

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


See full index

CPR1 Exam 2 > 13- Renal Phys (Pierce) > Flashcards

13- Renal Phys (Pierce) Flashcards

1
Q

What are the 3 layers of the glomerular filtration barrier?

A
  • Blood side*
    1) Capillary endothelium
    2) Glomerular basement membrane
    3) Podocyte epithelium
  • Urine side*
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the sizes of the molecules that can filter through the glomerular filtration barrier?

A

Molecules < 20 A are freely filtered

Molecules > 42 A are not filtered

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

This is a sticky biogel in the endothelial lumen of the glomerular endothelium.

A

Glycocalyx

***Pores in endothelial cells give rise to glycocalyx

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

What is the glycocalyx made up of?

A

Proteins (negatively charged)

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

Explain the filterability of the glycocalyx.

A

Small ions can filter relatively easily and large ions will not filter as well.

Charge is also important. Because the glycocalyx is negatively charged, then anions will not filter very easily. They are repelled. Neutral charged molecules can filter fairly well, and positive ions will filter the best.

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

What happens if the glycocalyx stops repelling negatively charged ions/proteins?

A

This increases their filtration and you get proteinuria (protein in the urine). This can occur in Nephrotoxic Serum Nephritis. Not good!

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

What is freely filtered through the glomerular barrier?

A

Water
Small solutes = glucose, amino acids, electrolytes

***Concentrations equal on both sides of membrane

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

What is not freely filtered through the glomerular barrier?

A 
Large molecules (proteins) 
Formed elements (cells)

***Minuscule amounts of protein are filtered

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

How do we calculate the urinary excretion amount?

A

Urinary Excretion = Amount filtered - Amount Reabsorbed + Amount Secreted

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

How do we calculate Tubular Reabsorption?

A

Tubular Reabsorption = Glomerular Filtration - Urinary Excretion + Amount Secreted

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

If excretion > filtration, then what must have occurred?

A

Tubular Secretion

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

What goes into the kidney must come out. X in artery = X in vein + X in ureter, which means…

A

Arterial input = Venous output + Urine output

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

How do we calculate urine excretion rate?

A

Urine Excretion Rate = (Ux) (V)

Ux = Urinary concentration of X
V = Urine flow rate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

This is the rate at which substances are removed (or cleared) from plasma.

A

Renal Clearance

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

Renal Clearance means the rate of removal by the ________.

A

Kidneys

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

Renal Clearance is the volume of plasma completely cleared of a substance by the kidneys per unit time. It is a _______ _______.

A

Flow Rate (unit is volume per unit time)

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

How do we calculate Renal Clearance?

A

Cx = [ (Ux) (V) ] / Px

Ux = Urinary concentration of X
V = Urine flow rate
Px = Plasma concentration of X
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

This is the volume of plasma filtered into the combined nephrons of both kidneys per unit time (mL/min). It is the fluid filtered across the glomerular capillaries into Bowman’s space.

A

Glomerular Filtrate

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

Glomerular filtrate is similar to plasma and free of what?

A

Free of protein and cells

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

Glomerular filtrate makes up _______ of the RBF (or RPF).

A

20%

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

What is the average GFR?

A

125 mL/min (180 L/day)

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

How do we calculate Filtration Fraction?

A

FF = GFR/RPF

***FF is also 20% of RPF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

This is the fraction of RBF (RPF) that is filtered across the glomerulus. It changes with ultrafiltration pressure and is influenced by blood pressure.

A

Filtration Fraction

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

As FF increases, the oncotic pressure of the efferent arteriole increases, facilitating reabsorption of tubular fluid. Why is this?

A

More fluid is leaving, so proteins left behind in the capillary are more concentrated. This causes pressure to increase.

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

T/F. Filtered Load and Filtration Fraction are interchangeable.

A

False. Filtered Load (a rate in mg/min) is not the same as Filtration Fraction (a ratio of GFR to RBF).

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

How do we calculate Filtered Load?

A

Filtered Load = GFR x (Px)

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

What are the variables at play for calculating net reabsorption?

A

GFR
Plasma concentration
Urine concentration
Urine flow rate

***Slide 24 of pre-lecture! IMPORTANT!

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

How do we calculated Filtered Load, Reabsorption, and Excretion?

A

Filtered Load = GFR x (Px)
Reabsorption = Filtered Load - Excretion
Excretion = (Ux) (V)

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

How can we use renal clearance to estimate GFR?

A

GFR = [ (Ux) (V) ] / Px

***This means GFR is directly proportional to renal clearance!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

GFR is directly proportional to renal clearance if…

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are examples of things that are freely filterable (meaning GFR is equal to renal clearance)?

A

Inulin

Creatinine

32
Q

In clinical situations, the GFR of a patient is usually determined by measuring the clearance of ________.

A

Creatinine

33
Q

Like Inulin, Creatinine is freely filtered at the glomerulus. However, in contrast to Inulin, a small amount of Creatinine is also __________ (approximately 10% of all Creatinine excreted in the urine reflects this component).

A

Secreted

34
Q

Because of its secretory component, Creatinine is not an ideal marker for GFR. Despite this error though, it is used to measure GFR because it is produced endogenously by _________ _________ and does not require an infusion.

A

Skeletal Muscle

35
Q

T/F. It is easy to do a Creatinine clearance, because the patient can do it at home by simply collecting their urine (usually over a 24 hr period) and having a single blood sample obtained to measure the plasma Creatinine.

A

True

36
Q

What are the effects of sympathetic stimulation to increase blood pressure and what receptors do they use?

A

Arterial resistance vessels – Powerful vasoconstriction: Afferent > Efferent arteriole
***Alpha1-Adrenergic Receptor

Juxtaglomerular granular cells – Renin release; + RAAS
***Beta1-Adrenergic Receptor

Tubular epithelial cells – Na/K ATPase; Increased Na+ reabsorption
***Alpha1-Adrenergic Receptor

37
Q

What pressure is P-GC?

A

Hydrostatic pressure within the glomerular capillary pushing outward

38
Q

What pressure is P-BC?

A

Hydrostatic pressure within Bowman’s Capsule pushing inward (into capillary)

39
Q

What pressure is πGC?

A

Oncotic (Colloid Osmotic) pressure within the glomerular capillary pulling inward (into capillary)

40
Q

What pressure is πBC?

A

Oncotic (Colloid Osmotic) pressure within Bowman’s Capsule pulling outward

***Under normal conditions, this is usually around 0

41
Q

What forces favor filtration?

A

Glomerular Hydrostatic Pressure (P-GC)

Bowman’s Capsule Oncotic (Colloid Osmotic) Pressure (πBC)

42
Q

What forces favor reabsorption?

A

Bowman’s Capsule Hydrostatic Pressure (P-BC)

Glomerular Capillary Colloid Osmotic Pressure (πGC)

43
Q

How do we calculate net filtration pressure?

A

Net filtration pressure = Glomerular Hydrostatic Pressure (P-GC) - Bowman’s Capsule Pressure (P-BC) - Glomerular Oncotic Pressure (πGC)

  • **Forces favoring filtration - Forces opposing filtration
  • **If positive, then filtration is occurring
44
Q

What 3 physical factors contribute to GFR?

A

1) Hydraulic conductivity (permeability/porosity of the fenestrated endothelium) = Lp
2) Surface area for filtration = Sf
3) Capillary ultrafiltration pressure = Puf

45
Q

What is the product of Lp and Sf?

A

Lp x Sf = Kf (Ultrafiltration coefficient)

46
Q

How do we calculate GFR using Lp, Sf, and Puf?

A

GFR = Kf x Puf

***Remember, Kf = Lp x Sf

47
Q

How can we calculate ultrafiltration pressure (Puf)?

A

Puf = (P-GC) - (P-BC) - (πGC)

***Same equation as for net filtration pressure

48
Q

What can alter Puf?

A

Changing glomerular capillary pressure (P-GC)

49
Q

What determines P-GC?

A

Renal arterial BP
Afferent arteriolar resistance
Efferent arteriolar resistance

50
Q

What role do glomerular mesangial cells play?

A

They have contractile properties, which causes change in surface area (Sf).

51
Q

Put the following in order from most to least hydrostatic pressure:

A) Glomerular Capillary
B) Peritubular Capillary
C) Renal Vein
D) Renal Artery
E) Intrarenal Vein
F) Afferent Arteriole
G) Efferent Arteriole
A

1) D.
2) F.
3) A.
4) G.
5) B.
6) E.
7) C.

52
Q

Where do the sharpest declines in hydrostatic pressure occur in renal vasculature?

A

Afferent Arteriole

Efferent Arteriole

53
Q

Why does the Glomerular Capillary have relatively high hydrostatic pressure?

A

It is a special case because it has to filter so much out of it constantly. It needs higher pressure to do this.

54
Q

What is the effect if the Afferent Arteriole is constricted?

A
    • Reduces filtration pressure (Puf)
    • GFR falls
    • Decreases RBF
55
Q

What is the effect if the Efferent Arteriole is constricted?

A
    • Increases filtration pressure (due to backup in capillary)
    • GFR increases
    • Decreases RBF
56
Q

What is the effect if the Afferent Arteriole is dilated?

A
    • Increases pressure driving filtration (Puf)
    • GFR increases
    • Increases RBF
57
Q

What is the effect if the Efferent Arteriole is dilated?

A

– Allows blood to easily escape capillary and pressure falls

– GFR decreases

– Increases RBF

58
Q

__________ primarily constricts efferent arteriole, which raises GFR, during diminished renal perfusion pressure. _______-inhibitors tend to lower GFR.

A

Angiotensin II

ACE

59
Q

Renal blood vessels are richly innervated by _________.

A

Sympathetics (via catecholamines)

60
Q

________ ________ is increasing reabsorption rate within the renal tubules when GFR rises.

A

Glomerulartubular Balance

61
Q

Describe the pressure change mechanism for Glomerulartubular Balance.

A

Changes in pressure in the efferent arteriole. Increased GFR means more water was filtered at the glomerulus, leaving behind a higher oncotic pressure in the efferent arteriole and peritubular capillary (PTC). Elevated oncotic pressure in the PTC promotes Na+ reabsorption.

62
Q

Describe the solute delivery mechanism for Glomerulartubular Balance.

A

Increased delivery of solutes to proximal tubule. Increased GFR results in a greater filtered load of all normally filtered substances (glucose, amino acids, etc.) Many co-transport Na+ in the proximal tubule, and this increased delivery of organic solutes that accompanies increased GFR stimulates preferential reabsorption of Na+.

63
Q

Describe the GFR rate and fluid flow mechanism for Glomerulartubular Balance.

A

Increased GFR rate and fluid flow through the proximal tubule increases shear strain on the apical microvilli, which up regulates apical sodium transporter insertion, which promotes Na+ reabsorption.

64
Q

Briefly describe Glomerulartubular Balance in very basic terms.

A

1) Increased peritublar capillary oncotic pressure
2) More stuff dumped into proximal tubule

***Both result in increased reabsorption rates in the tubules

65
Q

This maintains RBF and GFR within narrow limits across a wide range of arterial pressures. The stabilizing ability of blood flow is also apparent in the brain and heart.

A

Autoregulation

66
Q

T/F. Increasing pressure leads to decreased resistance.

A

False. Increasing pressure leads to increased resistance.

67
Q

Two forms of auto regulation are 1) local reflex between vascular smooth muscle cells (called _______ ______), and 2) physiological feedback via juxtaglomerular apparatus (called _________ _________).

A

Myogenic Reflex

Tubuloglomerular Feedback

68
Q

For the local myogenic feedback reflex, blood vessels resist stretch during periods of high blood pressure. Smooth muscle within the vessels contract (1-2 second delay) and there is Calcium signaling. There is Afferent Arteriolar (CONSTRICTION/DILATION) and Efferent Arteriolar (CONSTRICTION/DILATION).

A

Constriction

Dilation

69
Q

What is part of the Juxtaglomerular apparatus?

A
  1. Macula densa cells
  2. Juxtaglomerular (granular) cells – Renin
  3. Extraglomerular mesangial (lacis) cells
70
Q

Tubuloglomerular Feedback senses tubular ________ and feeds back signal to adjust arteriolar resistance as needed. The signals are between the Macula Densa cells and JG cells. This maintains constant ______ delivery to the distal tubule and constant GFR regulation. There is also Renin release.

A

NaCl

Na+

71
Q

Describe the steps of Macula Densa signaling.

A

1) Increased delivery of NaCl to the Macula Densa
2) Increased ATP/Adenosine
3) Vasoconstricts afferent arteriole (Calcium signaling)
4) Decreased GFR

***Also results in decreased Renin release

72
Q

In summary of the Tubuloglomerular Feedback, what do each of the components do?

A

Macula Densa “senses”
Mesangial Cells “transduce message”
Juxtaglomerular Cells “secrete renin”

73
Q

How do we calculate fractional excretion (FE)?

A

FE = [ (Ux) (Pcr) ] / [ (Px) (Ucr) ]

***It is the Amount of X excreted / Amount of X filtered

74
Q

If the fractional excretion is 1.0, what does that mean?

A

100% of whatever was filtered gets excreted

75
Q

If the fractional excretion is 0.9, what does that mean?

A

90% of whatever was filtered gets excreted (reabsorption occurred)

76
Q

If the fractional excretion is 1.1, what does that mean?

A

110% of whatever was filtered gets excreted (secretion occurred)

CPR1 Exam 2 (27 decks)

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