Renal I Flashcards
1
Q
Functional Unit of the kidney
A
Nephron
2
Q
The nephron does the work of making urine to remove waste and reabsorbing electrolytes to maintain the what?
A
ECF
Extra Cellular Fluid
3
Q
Loss of how many nephrons pushes you towards kidney failure/uremia?
A
> 50%
Loss of nephrons makes it more difficult to filter the blood
4
Q
Age of 40 does what with nephrons?
A
Decrease about 10% per decade or 1% per year
5
Q
Age of 80 does what with nephrons?
A
-40%; 480K-720K
6
Q
Net function of glomerulus?
A
Filters and hold capillary beds
7
Q
Net function of proximal tubule?
A
Reabsorbs salts and drug secretion
8
Q
New functions of descending LOH?
Loop of Henle
A
Reabsorbs water
9
Q
What are the mid to late parts of the nephron?
A
- Ascending loop of henle
- Distal convoluted tubule
- Collecting duct
10
Q
Net functions of ascending LOH?
A
NaCl reabsorption
11
Q
Net functions of collecting duct?
A
Adjusting water
12
Q
Where does ANGII constrict?
A
Proximal tubule
Reabsorb for NaCl
13
Q
Aldosterone and ADH effects what?
A
Collecting duct
Reabsorbs H2O and Urea
14
Q
Drug secretion is done by what?
In the proximal tubule
A
OAT’s and OCT’s
Organic anion/cation transporters
15
Q
Normal Plasma osmolarity
A
300 mOsm
16
Q
The size of kidneys is only how much of the body mass?
A
0.5%
17
Q
Kidney gets how much of the cardiac output?
A
20%
18
Q
Calculation of RBF:
A
5L/min x 20% = 1L/min
19
Q
Name the 9 steps of blood flow through kidney:
AIA-GEP-VIA
A
Arcuate artery
Interlobular artery
Afferent arteriole
Glomerulus
Efferent arteriole
Peritubular capillaries
Vasa recta
Interlobular vein
Arcuate vein
20
Q
Why does such a small organ get such a large amount of blood flow?
A
For the process of filtration because ischemia causes problems in nephron
21
Q
Where is there high pressure in the nephron and what is the function of that?
A
In the afferent arterial to the glomerulus
For filtration
22
Q
What does the high pressure look like with hydrostatic and oncotic pressure?
A
Hydrostatic > oncotic
Pushes out to get filtered
23
Q
Refresher: Hydrostatic pressure does what?
A
Pushes fluid out
24
Q
Refresher: Onconic pressure does what?
A
Pulls fluid in
25
Where is there low pressure in the nephron and what is the function of that?
Efferent arterial and peritubular capillaries
Reabsorption of fluid
26
What does the low pressure look like with hydrostatic and oncotic pressure?
Oncotic > hydrostatic
## Footnote
Pulls fluid in to reabsorb
27
What does the vasa recta provide pressure wise?
Low pressure osmotic counter current
28
What is counter current flow?
In countercurrent flow, the two flows move in opposite directions.
Two tubes have a liquid flowing in opposite directions, transferring a property from one tube to the other. For example, this could be transferring the concentration of a dissolved solute from a high concentration flow of liquid to a low concentration flow.
29
Filtered load equation?
Plasma [x] x GFR
30
What does the filtered load equation tell you?
How much is actually filtered
31
What is the 3 layer barrier in the glomerulus that helps promote filtration and limit what is able to cross into the nephron?
1. Fenestrated capillary endothelium
2. Glomerular basement membrane
3. Podocytes with filtration slits
32
What 3 things determine what crosses the membrane?
1. Glomerular filtration membrane
2. Size and charge of filtered molecules
3. Net filtration pressure
33
What charge is the glomerular basement membrane?
Negative
34
When sizes are equal, what charge has a harder time being filtered?
Negative charged substances
35
When sizes are equal, which charge substances are easily filtered?
Positively charged substances
36
From easiest to hardest what is filterable: inulin, glucose, albumin, water, sodium, myoglobin, urea, hemoglobin
Urea, glucose, sodium, water, inulin, electrolyes
Myoglobin
Hemoglobin
Albumin
37
What is the major driving force of filtration?
High P GC (glomerular capillary hydrostatic pressure)
38
Net filtration pressure (NFP) equation?
39
Normal Values for NFP
## Footnote
(50-10)-(25-0)= 40-25= +15mmHg (positive = out pressure)
40
Why is there no Bowman’s capsule colloid osmotic pressure?
Shouldn’t filter proteins because they don’t make it into the capsule
41
If you increase P GC then what happens to the filtration?
Increase
42
What 2 factors do GFR come down to?
1. Permeability glomerular capillary
2. Net filtration pressure (starling forces)
43
Rate at which filtrate is formed by both kidneys per minute
Glomerular filtration rate (GFR)
44
What is the key measure of renal health?
GFR
45
GFR is passive process that is driven largely by what?
NFP (particularly high P GC)
## Footnote
NFP: Net filtration pressure
46
What is the only thing that the glomerulus can not filter from plasma?
Proteins
47
Is it practical to measure GFR by Kf or NFP?
No
48
What represents how much of a substance can be removed from a certain amount of plasma volume in a given amount of time?
Clearance
## Footnote
Think volume of fluid = clearance. Not how much of the substance was removed.
49
We can use clearance to estimate what?
GFR
50
Clearance equation:
(U x UV) / P
| Unit: mL/min
## Footnote
U= solute in urine
UV= volume of urine
P= solute in arterial plasma
51
What is the gold standard to find renal clearance?
Inulin
52
What are the 4 reasons why inulin is ideal for renal clearance?
1. Non-toxic and infusible
2. Freely filterable by the kidney
3. Not reabsorbed, secreted, metabolized, synthesized or stored in any way
4. Unable to alter GFR
53
Clearance of inulin is equal to what?
GFR
54
What are the 4 steps to use inulin in renal clearance?
1. Infuse a substance into the pt
2. Achieve steady plasma conc
3. Collect urine and blood
4. Calculate clearance
55
What is the second best way to calculate renal clearance?
Creatinine
56
What are the 5 reasons why creatinine is used for renal clearance?
1. It’s a metabolite produced by creatinine phosphate metabolism (no infusion needed)
2. In normal healthy person the rate of production is constant (rate of production=rate of excretion)
3. Freely filterable by the kidney
4. Not reabsorbed
5. Small secretion into the nephron (~10%)
57
What are the 3 steps to use creatinine for renal clearance?
* Collect blood
* Measure creatinine
* Use prediction equation
58
How is plasma Cr related to GFR?
Inversely
59
Doubling plasma Cr represent what with GFR?
Large reductions
60
A 50% reduction in GFR from 125 to 62.5 induces what to plasma Cr?
100% increase from 1 to 2
61
Does GFR decline naturally with aging?
Yes
62
Stage 1 CKD; kidney damage with normal GFR
> 90 GFR
63
Stage 2 CKD; kidney damage with mild GFR
60-89 GFR
64
Stage 3A CKD; mild to moderate GFR
45-59 GFR
65
Stage 3B CKD; moderate GFR
30-45 GFR
66
Stage 4 CKD; severe GFR
15-30 GFR
67
Stage 5 CKD; kidney failure
<15 or dialysis GFR
68
What is the normal value of GFR?
125
69
GFR of both kidney in ml/min and L/day?
125 ml/min
180 L/day
70
bout how much of volume filtered (GFR) is reabsorbed?
~99%
71
What is the normal plasma volume (PV)
3L = filtered 60 x’s/day
72
What is the calculation for RBF:
5-6L x 20% = 1000-1200ml/min
73
How much RBF goes through the kidney when comparing body weight?
3.5mL/min/g (<0.5% Bodyweight)
74
What is the % plasma filtered into the renal tubules?
Filtration fraction (FF)
75
What is the FF equation?
GFR/ renal plasma flow (RPF)
76
What is the FF:
125mL / 600mL/min=20%
77
What is the normal renal plasma flow?
600 mL/min
78
Is O2 a critical factor for regulating RBF?
No
79
Is high RBF for filtration or metabolism?
Filtration, not metabolism
80
If we constrict only the AA what would happen to RBF, PGC, GFR?
Everything decreases
81
If we constrict only EA, what would happened to RBF, PGC, and GFR?
* Decrease RBF
* Increase PGC
* Maintain GFR
82
What does the kidney use to protect RBF and GFR from changes in MAP?
Neuroendocrine regulation and intrinsic autoregulation
83
What is the normal MAP for kidney?
80-180mmHg
84
What is neuroendocrine regulation?
Vasoconstrictors vs dilators
Can be impaired during disease (HTN)
85
Neuroendocrine influences what?
RBF
86
What does NE/Epi do to the RBF?
Decrease
| Constrict
87
Pain, stress, exercise, hemorrhage deals with what agent?
NE/Epi
88
Primary affect of ANGII and ADH/AVP and where?
Constrictor on EA
89
What does ANGII and ADH/AVP do to RBF?
Decrease
90
Countered in AA via NO and PG is affected with what agent?
ANGII and ADH/AVP
91
Adenosine (ATP) has what primary effect and where?
Constrictor on AA
92
What does adenosine (ATP) cause in RBF?
Decrease
93
Released of macula densa during increase tubular flow deals with what agent?
Adenosine (ATP)
94
NO primary effect and where?
Dilation on AA and EA
95
What does NO do to RBF?
Increase
96
Sheer stress; helps keep GFR constant despite constrictors deals with what agent?
NO
97
Renal prostaglandins primary effect and where?
Dilation on AA
98
What does renal prostaglandins do to RBF?
Increase
99
Helps keep GFR constant depsite constrictors deals with what agent?
Renal prostaglandins
100
ANP primary affect and where?
Dilation on AA
Constriction on EA
101
High atrial pressure deals with what agent?
Dilation of ANP
102
Dopamine primary effect and where?
Dilation on AA and EA
103
Dopamine causes what with RBF?
Increase
104
Stretching the vascular wall of blood vessel will have a reflexive contraction explains what?
Myotonic mechanism
105
The reflexive contraction in myogenic mechanism is a what property?
Intrinsic property of smooth muscle
106
Each nephrons distal tubules (downstream), can communicate with the arterials of the glomerulus (upstream) to alter GFR explains what?
Tubuloglomerular feedback (TGF)
107
When Na in distal tubules is high, what happens with the GFR?
Lower
108
When Na in distal tubules is low, what happens to GFR?
Rises
109
Tubuloglomerular feedback helps keep what in nephron constant, which helps maintain ECFV?
GFR and Na
110
Renal triad of AKI is:
| Acute Kidney Injury
Decrease in GFR
Decrease in urine output
Increase in BUN
111
What is the first step of urine production?
Filtration
112
Sevoflurance represents a theoretical risk for what?
AKI
