Chapter 4 Flashcards
(195 cards)
1
Q
nephron is a functional unit of-
A
the kidney
2
Q
how many nephrons does each kidney contain?
A
1 - 1.5 million
3
Q
2 types of nephrons-
A
-cortical
-juxtamedullary
4
Q
cortical nephrons are situated within-
A
the cortex of the kidney
5
Q
cortical nephron are responsible for- (2)
A
-removal of waste products
-reabsorption of nutrients
6
Q
cortical nephrons make up appx. ____% of nephrons
A
85%
7
Q
juxtamedullary nephrons have longer-
A
loops of Henle
8
Q
you can tell juxtamedullary nephrons from cortical cortical nephrons because-
A
juxtamedullary are longer
9
Q
juxtamedullary nephrons extend-
A
deep into the medulla of the kidney
10
Q
primary function of juxtamedullary nephrons-
A
urine concentration
11
Q
renal functions- (4)
A
-blood flow
-glomerular filtration
-tubular reabsorption
-tubular secretion
12
Q
renal blood flow path- (7)
A
-renal artery
-glomerulus
-efferent arteriole
-proximal convoluted tubule
-vasa recta/loops of henle
-distal convoluted tubule
-renal vein
13
Q
afferent arterioles supply blood to-
A
kidneys
14
Q
glomerulus receives blood from-
A
afferent arteriole
15
Q
blood leaves the glomerulus & goes to-
A
efferent arieriole
16
Q
vessels in renal blood flow assist in-
A
maintaining hydrostatic pressure differential
17
Q
total renal blood flow is appx-
A
1200 mL/min
18
Q
total renal plasma flow ranges from-
A
600 - 700 mL/min
19
Q
average body size for total renal plasma flow-
A
1.73 m^2 surface
20
Q
correction for variance in body surface area must-
A
be calculated
21
Q
glomerulus consists of-
A
coil of appx. 8 capillary lobes
22
Q
the glomerulus coil of 8 capillary lobes walls are referred to as-
A
glomerular filtration barrier
23
Q
glomerulus located within-
A
Bowmans capsule
24
Q
glomerulus serves as-
A
nonselective filtration
25
glomerulus filtration factors- (3)
-cellular structure
-hydrostatic & oncotic pressure
-renin-angiotensin-aldosterone system
26
glomerular filtration barrier cellular layers- (3)
-capillary wall
-basement membrane
-bowman's capsule inner layer
27
endothelial cells of glomerulus capillary walls differ in other capillaries because- (2)
-endothelial cells have pores (aka fenestrated)
-large molecules & cells are blocked
28
the basement membrane causes further restriction of-
large molecules as filtrate passes through it
29
bowman's capsule inner layer includes-
the thin membranes covering filtration slits formed by the intertwining foot processes of podocytes
30
glomerulus shield of negativity repels-
molecules with a negative charge even though they are small enough to pass through the glomerular filtration barrier
31
the shield of negativity is important because-
it is where albumin (associated with renal disease) has a negative charge & is repelled
32
juxtaglomerular apparatus regulates-
arteriole size
33
juxtaglomerular apparatus maintains-
consistent glomerular blood pressure
34
low blood pressure in juxtaglomerular apparatus-
-larger (dilation) afferent arterioles & smaller (constricted) efferent arterioles
-prevents decreased glomerular blood flow
35
an increase in blood pressure in juxtaglomerular apparatus-
-constricts (smaller) afferent arterioles
-prevents overfiltration & damage to glomerulus
36
Renin-Angiotensin- Aldosterone System (RAAS) regulates-
blood flow to & within the glomerulus
37
RAAS responds to changes in-
blood pressure & plasma sodium changes
38
juxtaglomerular apparatus consists of- (2)
-juxtaglomerular cells
-macula densa
39
juxtaglomerular cells are in the-
afferent arterioles
40
macula densa are in the-
efferent arteriole (distal convoluted tubule)
41
when macula densa senses a change in blood pressure-
initiates a cascade of reactions in the RAAS
42
renin produced/secreted by-
juxtaglomerular cells
43
angiotensinogen is a-
blood substrate
44
angiotensin I passes through-
lungs
45
after angiotensin I passes through the lungs, angiotensin-converting enzyme (ACE) changes it to-
the active form angiotensin II
46
aldosterone-
sodium-retaining hormone
47
angiotensin II corrects renal blood flow by- (5)
-dilates afferent arterioles
-constricts efferent arterioles
-stimulates sodium & water in proximal convoluted tubules
-triggers the release of aldosterone
-triggers the release of antidiuretic hormone
48
normal glomerular filtration-
120 mL/min of filtrate
49
RAAS Composition-
ultrafiltrate of plasma
50
only difference between the compositions of the filtrate & the plasma is-
the absence of plasma proteins, protein-bound substances, & cells
51
analysis of the fluid as it leaves the glomerulus shows the filtrate specific gravity to be-
1.010
52
tubular reabsorption starts when-
the plasma ultra filtrate enters the proximal convoluted tubules
53
for active transport to occur in tubular reabsorption-
carrier proteins & cellular energy are needed for transport back to the blood
54
active transport is responsible for the reabsorption of- (3)
-glucose, salts (Na is highest), & amino acids in the proximal convoluted tubules
-chloride in ascending loop of henle
-sodium in distal convoluted tubules
55
passive transport is controlled by-
the differences in substance concentration gradients on opposite sides of a membrane
56
passive reabsorption of water takes place-
throughout the nephron, except in the loop of henle
57
passive reabsorption of water accompanies-
high amounts of sodium reabsorption in proximal convoluted tubules (PCT)
58
urea is passively reabsorbed in- (2)
-PCT
-ascending loop of henle
59
sodium is passively reabsorbed in-
ascending loop of henle
60
maximal reabsorptive capacity (Tm)-
plasma concentration of a substance that is normally completely reabsorbed reaches an abnormally high level
61
renal threshold-
plasma level causing active transport to cease
62
for glucose, the plasma renal threshold is-
160 - 180 mg/dL
63
renal threshold & plasma concentration can be used to distinguish between-
excess solute filtration & renal tubular damage
64
passive reabsorption of water into the high osmotic gradient of the renal medulla (water removed by osmosis) occurs in-
descending loop of henle
65
actively reabsorbed in the ascending loop of henle-
chloride
66
passively reabsorbed in the ascending loop of henle-
sodium
67
walls of the ascending loop of henle are-
impermeable to water
68
countercurrent mechanisms serves to maintain-
the osmotic gradient in the medulla
69
in countercurrent mechanisms, the medulla is diluted by-
water from the descending loop
70
counter current mechanisms are reconcentrated by-
sodium & chloride from the filtrate in the ascending loop
71
aldosterone controls-
sodium (Na) reabsorption if needed by the body
72
collecting duct concentration is the final-
filtrate concentration
73
collecting duct concentration water reabsorption is controlled by-
ADH in response to body hydration
74
reabsorption in the final filtrate concentration depends on-
osmotic gradient in the medulla
75
the hormone vasopressin is also known as-
antidiuretic hormone (ADH)
76
ADH controls the permeability of-
distal convoluted tubules & collecting duct walls to water
77
amount of ADH produced by the posterior pituitary determines-
permeability
78
final determinant of urine volume & concentration-
the chemical balance in the body
79
increased body hydration =
decreased ADH = increased urine volume
80
decreased body hydration=
increased ADH = decreased urine volume
81
tubular secretion involves the passage of substances from-
the blood in peritubular capillaries to the tubular filtrate
82
tubular secretion differs from reabsorption because reabsorption-
carries substances from the tubular filtrate into the blood
83
tubular secretion eliminates non filtered waste by- (2)
-protein-bound substances
-regulate acid-base balance
84
eliminating non filtered waste by regulating acid-base balance secretes-
H+ ions to return filtered buffers to the blood
85
eliminating non filtered waste by regulating acid-base balance excretes-
excess H+ ions
86
normal blood pH-
7.4
87
to maintain a normal blood pH of 7.4, the blood must-
buffer & eliminate excess acid formed by dietary intake & body metabolism
88
bicarbonate (HCO3) is returned to blood by-
secretion of hydrogen ions (H+) into filtrate
89
bicarbonate (HCO3) returned to blood provides for-
100% of bicarbonate reabsorption
90
all 3 secretory functions of hydrogen ions occur-
at rates determined by the acid-base balance in the body
91
a disruption in these secretory functions causes- (2)
-metabolic acidosis
-renal tubular acidosis
92
clearance tests measure-
the rate at which the kidneys can remove a filterable substance from the blood
93
to ensure glomerular filtration is being measured accurately-
the substance analyzed cannot be reabsorbed or secreted by the tubules
94
factors to consider when selecting a clearance test substance- (4)
-stability of substance in urine during a long collection time (poss. 24 hrs)
-consistency of plasma level
-availability to the body
-availability of tests to measure the substance
95
primary substances used in clearance tests- (4)
-creatinine
-beta2 microglobulin
-cytatine C
-possibly radioisotopes
96
exogenous procedure is termed-
test that requires an infused substance
97
endogenous procedure is termed-
the method of choice if a suitable test substance is already present in the body
98
a waste product of muscle metabolism-
creatinine
99
creatinine links with-
adenosine triphosphate to produce adenosine diphosphate & energy
100
creatinine is found at-
a constant level in the blood
101
creatinine clearance is a _____ procedure-
endogenous
102
103
newer methods of creatinine clearance for GFR have been developed that use-
serum creatinine, cystatin C, or B2M values
104
newer methods of creatinine clearance for GFR testing are reported as-
estimated glomerular filtration rate (eGFR)
105
greatest error in any clearance procedure using urine is-
improperly timed urine specimens
106
GFR is reported in-
milliliters per minute (mL/min)
107
principle of a GFR-
to determine the amount of creatinine (mL) completely cleared from the plasma during 1 min.
108
urine volume is measured in-
milliliters per minute (V)
109
urine creatinine is measured in-
mg/dL (U)
110
plasma creatinine is measured in-
mg/dL (P)
111
creatinine is produced as a result of-
muscle destruction, therefore normal values are based on size (larger person, more creatinine produced)
112
normal creatinine values in men-
107 - 139 mL/min
113
normal creatinine values in women-
87 - 107 mL/min
114
normal reference range of plasma creatinine is-
0.6 - 1.2 mg/dL
115
normal values are lower in-
older people
116
used to adjust for actual body surface area-
nomograms
117
eGFR equations are superior to serum creatine solely because they include variables for- (3)
-race
-age
gender
118
eGFR methods correspond most closely to-
isotope dilution mass spectrophotmetry
119
eGFR calculations are Mande on-
average body size
120
eGFR results with numerical values below 60 mL/min should be reported as-
59 mL/min for example
121
eGFR results with higher values equal or greater than 60 mL/min should be reported as-
> or equal to 60 mL//min for example
122
GFR for stage 1 of chronic kidney disease-
> or equal to 90 mL/min/1.73 m
123
GFR for stage 2 of chronic kidney disease-
between 60 &89 mL/min/1.73 m
124
GFR for stage 3 of chronic kidney disease-
between 45 & 59 mL/min/1.73 m
125
GFR for stage 4 of chronic kidney disease-
between 15 & 29 mL/min/1.73 m
126
GFR for stage 5 of chronic kidney disease-
< or equal to 15 mL/min/1.73 m (end stage renal disease)
127
good procedure for screening & monitoring GFR-
cystatin C
128
cystatin C is a small protein produced by _____ & filtered by ______-
-produced by all nucleated cells
-filtered by the glomerulus
129
cystitis c is absorbed & broken down by-
renal tubular cells, therefore no cystitis c is secreted
130
serum levels directly reflect-
GFR
131
monitoring cystitis c levels is recommended for- (4)
-pediatrics
-diabetics
-elderly
-critically ill
132
B2M is a small protein that-
dissociates from human leukocyte antigens at a constant rate
133
B2M is rapidly removed from the plasma by-
the kidneys
134
B2M used to identify- (2)
-end-stage renal disease
-early rejection of kidney transplant
135
B2M is a sensitive indicator of-
a decrease in GFR
136
B2M isn't reliable in patients who-
have immunologic disorders or malignancy
137
tubular reabsorption tests are a good indicator of-
early renal disease
138
tubular reabsorption tests measure-
renal concentrating ability (salt & water)
139
tubular reabsorption tests are often termed-
concentration tests
140
tubular reabsorption tests are the baseline for determining-
the concentration is the 1.010 specific gravity of the original ultrafiltrate
141
necessary for accurate results in tubular reabsorption tests-
control of fluid intake
142
tubular reabsorption tests controlled intake procedures can include-
overnight deprivation of fluid for 12 hours followed by collection of a urine specimen
143
normal urine osmolality readings-
800 mOsm or higher
144
urine to serum ratio indicated normal tubular reabsorption-
3:1 or greater
145
osmolarity has replaced specific gravity as the test to assess-
renal concentration
146
osmolality is performed for-
a more accurate evaluation of renal concentrating ability
147
primary urine method-
freezing-point osmometers
148
freezing-point osmometer measured sample is-
supercooled & vibrated to form crystals
149
heat of fusion by the crystalizing water temporarily-
raises temperature to freezing point
150
probe measures-
freezing point
151
1 mol (1000 mOsm) of nonionizing substance in 1 kg water lowers freezing point to-
1.86 C
152
clinical osmometers uses _____ as their standard-
NaCl
153
vapor pressure osmometers actual measure is-
dew point (temperature at which water vapor condenses to a liquid)
154
microsamples on small filter-paper disks are placed in sealed chambers-
evaporating samples form vapor
155
when the temperature in the chamber is lowered, vapor condenses & thermocouples measures-
heat of condensation that raised the temperature to dew point
156
vapor pressure osmometers requires careful technique because of-
micro samples commonly used for serum samples
157
lipemic serum affects- (2)
-vapor pressure
-freezing point osmometers
158
lipemic serum insoluble lipids produce-
erroneous results
159
lactic acid elevates reading in- (2)
-vapor pressure
-freezing point osmometers
160
lactic acid specimens should be separated within-
20 minutes
161
volatile/ethanol specimens elevate results for-
freezing point osmometers
162
major clinical uses of osmolarity include- (5)
-Evaluating renal concentrating ability
-Monitoring course of renal disease
-Monitoring fluid & electrolyte therapy
-Differential diagnosis of hyponatremia & hypernatremia
-Evaluating secretion of & response to ADH
163
serum osmolality reference values are-
275 - 300 mOsm
164
can influence urine concentration- (2)
-fluid intake
-urine concentration
165
ratio of urine to serum osmolality should be-
1:1
166
ratio of urine to serum osmolality after controlled fluid intake should be-
3:1
167
the ratio of urine to serum osmolality is used to determine if diabetes insipidus is caused by- (2)
-decreased ADH production
-inability of tubules to respond to ADH
168
failure to achieve a 1:1 ratio after ADH injection indicates-
no ADH receptors are in the collecting duct
169
achieving a 3:1 ratio after ADH injection indicates-
collecting duct has an inability to produce ADH
170
free water clearance expands-
urine to serum osmolarity ratio
171
osmolar clearance is preformed first using- (3)
-water deprivation
-timed urine
-serum
172
osmolar clearance indicates-
how much water must be cleared each minute to produce a urine with the same osmolality as the plasma
173
calculation of free water clearance determines-
the ability of the kidneys to respond to the body’s state of hydration
174
tubular secretion & renal blood flow tests are related because-
secretion os dependent on renal blood flow
175
tubular secretion & renal blood flow tests interpretation requires an understanding of-
the principles & limitations of the tests
176
test most commonly associated with tubular secretion & renal blood flow tests-
p-aminohippuric acid test (PAH)
177
PAH in renal blood flow tests is secreted in-
proximal convoluted tubule
178
PAH in renal blood flow tests are loosely bound to-
plasma proteins
179
PAH in renal blood flow tests is completely removed from the blood each time it-
comes into contact with functional renal tissue
180
PAH tests are ____ procedures-
exogenous
181
normal values in PAH tests are based on-
Hct
182
average renal blood flow in PAH tests-
1200 mL/min
183
normal renal blood flow in PAH tests-
600 - 700 mL/min
184
appx. _____% of renal blood flow doesn't come in contact with functional renal tissue-
8%
185
Titratable Acidity and Urine Ammonia tests for-
tubular secretion of H+ & NH4+
186
normal excretion for Titratable Acidity and Urine Ammonia-
70 mEq/day of acid in the form of H+, H2PO4-, & NH4+
187
alkaline tides appear- (2)
-first morning
-postprandial 2 - 8 pm (lowest pH at night)
188
renal tubular acidosis is the inability to-
produce an acid urine in the presence of metabolic acidosis
189
proximal convoluted tubules secrete-
H+
190
distal convoluted tubules secrete-
NH3
191
Titratable Acidity and Urine Ammonia measure- (3)
-pH
-titratable acidity
-ammonia
192
prime patients for Titratable Acidity and Urine Ammonia with-
acid load of ammonium chloride
193
run Titratable Acidity and Urine Ammonia tests can be run on- (2)
-2 hr urine specimens
-fresh or toluene specimens
194
by titrating the amount of free H+ &then the total acidity, the ammonium concentrate can calculate the difference of- (2)
-titratable acidity
-total acidity
195
total acidity minus titratable acidity=
ammonia
