Renal Physiology Flashcards
1
Q
What do you call the maintenance of the internal environment compatible with life?
A
Homeostasis
2
Q
What is the net gain of water per day?
A
Zero: Fluid gained per day = fluid lost per day
3
Q
Which organ system contributes to homeostasis by adjusting water and electrolyte levels?
A
Renal System: mainly by producing urine
4
Q
What is urine?
A
Urine is an ultrafiltrate of blood
5
Q
Waste product from Proteins
A
Urea
6
Q
Waste product from Purines
A
Uric Acid
7
Q
Waste product from Muscles
A
Creatinine
8
Q
Waste product from RBCs
A
Bilirubin
9
Q
Excretion of variable amounts of water and sodium; Involved in RAAS
A
Blood pressure regulation
10
Q
Excretion of excess acids and bases
A
Regulation of Acid- Base balance
11
Q
Increases RBC production in response to hypoxia
A
Production of Erythropoeitin (EPO)
12
Q
Produces glucose during the starvation state
A
Gluconeogenesis
13
Q
Location of Kidney
A
T12-L3
14
Q
Weight of Kidney
A
150g
15
Q
Highly-fenestrated, responsible for GFR
A
Glomerular Capillaries
16
Q
Supplies O2 & glucose to the tubular cells
A
Peritubular Capillaries
17
Q
Secretes Erythropoietin (EPO)
A
Interstitial Cells
18
Q
Hairpin loop-shaped peritubular capillaries of the juxtaglomerular nephrons that participate in countercurrent exchange
A
Vasa Recta
19
Q
Capacity of the Urinary Bladder
A
600ml
20
Q
Urge to urinate
A
150ml
21
Q
Reflex contraction of the Urinary Bladder
A
300ml
22
Q
Bladder muscle
A
Detrusor muscle
23
Q
Internal Urethral Sphincter
A
Involuntary
24
Q
External Urethral Sphincter
A
Voluntary
25
Functional and Structural Unit of Kidney
Nephron
26
of Nephrons per kidney
1 million
27
75% of nephrons
Cortical Nephrons
28
25% of nephrons
Juxtamedullary Nephrons
29
Location of Cortical Nephrons
Renal Cortex
30
Location of Juxtamedullary Nephrons
Corticomedullary Junction
31
Loops of Cortical Nephrons
Short
32
Loops of Juxtamedullary Nephrons
Long
33
Capillary Network of Cortical Nephrons
Peritubular Capillaries
34
Capillary Network of Juxtamedullary Nephrons
Vasa Recta
35
The only capillaries in the body which drain into arterioles
Glomerular Capillaries
36
50x more permeable than skeletal muscle capillaries; Highly fenestrated with pores 8 nanometer in diameter
Capillary Endothelium
37
Capillary endothelium secretes:
Nitric Oxide & Endothelin-1
38
Have large spaces; With Type IV Collagen, Lainin, Agrin, Perlecan, Fibronectin
Basement Membrane
39
Found in between capillaries; Contractile, mediates filtration, take up immune complexes; Involved in Glomerular Diseases
Mesangial Cells
40
Cells of capillary endothelium
Podocytes
41
Parts of Podocytes
Foot processes Filtration slits with filtration slit diaphragm
42
Filtration Slit Diaphragm is made up of:
NephrinNEPH-1PodocinAlpha-actinin 4CD2-AP
43
"Glomerular cells of the Afferent Arterioles"; At the walls of Afferent Arterioles; Secrete Renin
JG Cells
44
Found in the walls of the Distal Convoluted Tubule; Monitor Na+ concentration in the DT (and consequently, blood pressure)
Macula Densa
45
"Visceral Epithelium" of the kidney
Podocytes
46
"Parietal Epithelium" of the kidney
Bowman's capsule
47
What are the filtration and charge barriers?
EndotheliumBasement membraneFoot processes of Podocytes
48
What is the charge of this charge barrier and what does it block?
NegativePrevents filtration of albumin and other negatively-charged proteins
49
Movement from Glomerular Capillaries to Bowman's space
(Glomerular) Filtration
50
Movement from tubules to interstitium to peritubular capillaries
(Tubular) Reabsorption
51
Movement from peritubular capillaries to interstitium to tubules
(Tubular) Secretion
52
(Amount Filtered) - (Amount Reabsorbed) + (Amount Secreted)
Excretion
53
Amount filtered in the glomerular capillaries per unit time
GFR
54
Normal GFR
125ml/min or 180L/day
55
GFR/RPF
Filtration fraction
56
Filtered freely
20 angstrom or less
57
Not filtered at all
> 42 angstrom
58
Afferent Arteriole Dilatation
GFR increases
59
Afferent Arteriole Constriction
GFR decreases
60
Efferent Arteriole Dilation
GFR decreases
61
Efferent Arteriole Constriction (moderate)
GFR increases
62
Efferent Arteriole Constriction (severe)
GFR decreases
63
Increased GC Hydrostatic pressure
GFR increases
64
Increased GC Oncotic pressure
GFR decreases
65
Increased BS Hydrostatic pressure
GFR decreases
66
Increased Kf
GFR increases
67
What are the causes of decreased Kf?
Renal Diseases DMHPN
68
What is the cause of increased BS hydrostatic pressure?
Urinary Tract Obstruction
69
What are the causes of decreased GC hydrostatic pressure?
Hypotension (Decreased arterial pressure)ACE-I (Decreased efferent arteriole constriction)Sympathetic Activity (Increased afferent arteriole constriction)
70
What are the hormones that will increase GFR?
EDFRPGE2PGI2BradykininGlucocorticoidsANPBNP
71
Which hormone will preserve GFR?
Angiotensin II (preferentially constricts efferent arteriole)
72
Which hormone will increase Renal Blood Flow (RBF)?
HistamineDopamineANPBNP
73
What is one possible effect of ACE-I in a patient with HPN secondary to Renal Artery Stenosis?
Renal Failure
74
(Renal Artery Pressure-Renal Vein Pressure) / Total Renal Vascular Resistance; Exhibits local autoregulation at BP between 75-160mmHg
Renal Blood Flow
75
What do you call massive sympathetic stimulation that results in massive vasoconstriction of the kidneys?
CNS Ischemic Response
76
"Constant sodium load delivered to distal tubule"; Primary Mechanism for Autoregulation of GFR
Tubuloglomerular Feedback
77
Vasoconstricts afferent arteriole
Adenosine
78
Vasodilates afferent arterioles
Nitric Oxide
79
"Percentage of solute reabsorbed is held constant"; Buffers effects of drastic GFR changes in urine output
Glomerulotubular Balance
80
Substance start to appear in the urine; Some nephrons exhibit saturation
Renal Threshold
81
All excess substance appear in the urine; All nephrons exhibit saturation
Renal Transport Maximum
82
Does not have Transport Maximum and Threshold
Gradient-time Transport
83
Gradient-time Transport: Rate of transport is dependent upon:
Electrochemical gradientMembrane permeabilityTime
84
"Workhorse of the Nephron"; With low columnar with extensive brush border (microvilli)
Proximal Convoluted Tubule
85
Reabsorption in Proximal Convoluted Tubule
100% filtered Glucose and Amino Acids66% NaCl and water
86
Secretion in Proximal Convoluted Tubule
H+, organic acids, bases (Rapidly filtered and almost none reabsorbed)
87
Which is more hypertonic relative to the other - fluid entering the PCT or fluid leaving the PCT?
None (isoosmotic reabsorption takes place)
88
Thin segment lining of Loop of Henle
Simple squamous with no brush border and few mitochondria
89
Thick segment lining of Loop of Henle
Simple cuboidal
90
With graded osmolarity; Constant: 20% filtered water is reabsorbed and 25% Na, K, Cl is reabsorbed; H is secreted via Na-H countertransport
Loop of Henle
91
Impermeable to solutes; Permeable to water
Descending Limb of Loop of Henle
92
Impermeable to water; Permeable to solutes
Ascending Limb of Loop of Henle
93
Contains juxtaglomerular apparatus, macula densa, juxtaglomerular cells (JG Cells), Lacis cells; Similar characteristics to thick segment of LH (relatively impermeable to water)
Early Distal Tubule (1st Part of the Distal Tubule)
94
Contains principal cells, intercalated cells; Responsive to effects of Aldosterone
Late Distal Tubule (2nd Part of the Distal Tubule)
95
Absorb Na (using ENaC channels) water and Secrete K
Principal Cells
96
Absorb K and Secrete H
Intercalated Cells
97
Where K sparing diuretics acts
ENaC Channels
98
Site of regulation of final urine volume and concentration; Responsive to Vasopressin
Collecting Duct
99
Maximum urine osmolality
1200mosm/L
100
Minimum Urine Volume
500ml
101
Increased by increased BP; Decreased by Afferent or Efferent Arteriole vasoconstriction
Peritubular Capillary Hydrostatic Pressure
102
Increased by Plasma protein concentration and Filtration fraction
Peritubular Capillary Oncotic Pressure
103
What happens to tubular reabsorption when Peritubular Capillary Hydrostatic Pressure increases?
Decreases
104
What happens to tubular secretion when Peritubular Capillary Hydrostatic Pressure increases?
Increases
105
What happens to tubular reabsorption when Peritubular Capillary Oncotic Pressure increases?
Increases
106
What happens to tubular secretion when Peritubular Capillary Oncotic Pressure increases?
Decreases
107
Site of Action of Aldosterone
Distal Tubule
108
Site of Action of Angiotensin II
PCTTALLHDT
109
Site of Action of Catecholamines
PCT TALLHDT/CD
110
Site of Action of Vasopressin
DTCD
111
Site of Action of ANP/BNP
DTCD
112
Site of Action of Uroguanylin, Guanylin
PCTCD
113
Site of Action of Dopamine
PCT
114
Site of Action of PTH
PCTTALLH
115
Effects of Aldosterone
Increase Na, water reabsorptionIncrease K, H secretion
116
Effects of Angiotensin II
Increase Na and water reabsorption
117
Effects of Catecholamines
Increase Na, water reabsorption
118
Effects of Vasopressin
Increase water permeability and reabsorption
119
Effects of ANP and BNP
Decrease Na reabsorption
120
Effects of Uroguanylin and Guanylin
Decrease Na, water reabsorption
121
Effects of Dopamine
Decrease Na, water reabsorption
122
Effects of PTH
Decrease Phosphate reabsorptionIncrease Ca reabsorptionStimulates 1 Alpha Hydroxylase
123
What are the triggers for ADH secretion?
Increased Plasma OsmolarityDecreased Blood PressureDecreased Blood Volume
124
What is the effect of alcohol on ADH secretion?
Alcohol decreases ADH secretion
125
Which hormone secreted by DT and CD acts similar to ANP?
Urodilatin
126
Rate at which substances are removed (cleared) from plasma in the kidneys
Renal Clearance
127
If a substance has a high clearance, what are the blood and urine level of this substance?
Low Blood levelHigh Urine level
128
If a substance has a low clearance, what are the blood and urine level of this substance?
High Blood levelLow Blood level
129
Which substance has the highest clearance?
Para-Amino Hippuric Acid (PAH)
130
Which substances have the zero clearance?
Glucose, Amino Acids
131
Which substances have a clearance that can be used to estimate GFR?
Inulin, Creatinine (BUN and Creatinine serum concentration may also be used)
132
Which substances have a clearance that can be used to estimate Renal Blood Flow and Renal Plasma Flow?
Para-Amino Hippuric Acid (PAH)
133
Substances that do not appear in the urine have a clearance of
Zero
134
Substances filtered and partially reabsorbed have a clearance ? Than the GFR
Less
135
Substances filtered and with net secretion have a clearance ? Than the GFR
More
136
Clearance of Inulin is ? To that of the GFR
Equal
137
How many liters of fluid per day passes thru the kidneys?
180L of fluid/day
138
Percentage of filtered water that is reabsorbed
87-98.7%
139
Plays major role in water reabsorption
Vasopressin and ADH
140
Threshold of Glucose
200mg/100ml
141
Maximum of Glucose
375mg/100ml
142
Region between threshold and maximum
Splay
143
Glucose transport from the lumen to PCT
SGLT-2 (Secondary Active Transport)
144
Glucose transport form the PCT to the Peritubular Capillaries?
GLUT-1 and GLUT-2 (facilitated diffusion)
145
Major role in electrolyte balance
Na
146
Na is actively transported in all parts of the renal tubule EXCEPT
Descending limb of Loop of Henle
147
Plasma K
4.2mEq/L
148
Can cause Arrhythmias
HyperkalemiaHypercalcemia
149
Can cause weakness
Hypokalemia
150
First line of defense
Movement of K across ECF to ICF
151
Factors that shift K into cells
InsulinAldosteroneB-Adrenergic StimulationAlkalosis
152
Factors that shift K out of cells
Insulin DeficiencyAddison's DiseaseB-Adrenergic BlockadeAcidosisCell lysisStrenuous ExerciseIncrease ECF Osmolarity
153
Increased Plasma K increases secretion via
Principal Cells
154
Decreased Plasma K increases reabsorption via
Intercalated Cells
155
Causes of Increased K secretion
High K doetHyperaldosteronismAlkalosisThiazide diureticsLoop diureticsLuminal anions
156
Causes of decreased K secretion
Low K dietHypoaldosteronismAcidosisK sparing diuretics
157
Plasma Ca
2.4mEq/L
158
Can cause Tetany
Hypocalcemia
159
Less calcium bound to plasma proteins
Hypercalcemia (Acidosis)
160
More calcium bound to plasma proteins
Hypocalcemia (Alkalosis)
161
Factors that alter renal calcium excretion: Decreased excretion
Increased PTH, Plasma PhosphateDecreased ECF, BPMetabolic AcidosisVit D3
162
Factors that alter renal calcium excretion: Increased excretion
Increased ECF, BPDecreased PTH, Plasma PhosphateMetabolic Alkalosis
163
Trio of Electrolytes: High H levels
HypercalcemiaHyperkalemia
164
Transport maximum of phosphate
0.1mM/min
165
Plasma Mg
1.8mEq/L
166
Magnesium stored in the bones
50%
167
Plasma Mg excreted daily
10%
168
Percentage of water reabsorbed automatically before the collecting duct
87%
169
If ADH levels are high, what happens to water reabsorption at the collecting duct?
High (more aquaporins inserted)
170
If ADH levels are high, what happens to urine volume at the collecting duct?
Low (min:500ml/day)
171
If ADH levels are high, what happens to urine concentration at the collecting duct?
High (max:1200mOsm/L)
172
If ADH levels are low, what happens to water reabsorption at the collecting duct?
Low (less aquaporins inserted)
173
If ADH levels are low, what happens to urine volume at the collecting duct?
High (max:20L/day)
174
If ADH levels are low, what happens to urine concentration at the collecting duct?
Low (min:50mOsm/L)
175
Provides the stimulus for water reabsorption
Countercurrent Mechanism
176
Provides the opportunity for water reabsorption
ADH
177
Countercurrent Multipliers
Loop of Henle
178
Creates the Corticopapillary Osmotic Gradient in the Renal Interstitium
Countercurrent Multipliers
179
Countercurrent Exchangers
Vasa Recta
180
Maintains the Cirticopapillary Osmotic Gradient in the Renal Interstitium (prevents dissipation of gradient)
Countercurrent Exchangers
181
Why is the Loop of Henle able to act as a countercurrent multiplier?
Countercurrent Flow (hairpin-loop shape)Difference in permeability to water and electrolytes in the Ascending and Descending WallNa-K-2Cl pump in the TAL LHSlow Flow in the LH
182
What is the end result due to the countercurrent mechanism?
Corticopapillary Osmotic Gradient: 300mOsm/L as you enter the PCT, 1200mOsm/L at the tip of LH
183
Why do you need a countercurrent exchanger?
Gradient would dissipate quickly if Na and Urea are removed quicklyVasa Recta preserves this gradient basically by "rotating" Na, water and urea
184
Contributes to the hyperosmolarity of the renal medulla
Urea Recycling
185
Percentage of Renal Medullary Interstitial Osmolarity
50%
186
Stimulated by ADH
Urea Receptors (UT-1)
187
Osmolarity at the tip of LH
600-1200mOsm
188
True or False: More urea reabsorbed, the more concentrated the renal interstitium becomes, the more concentrated the final urine is
True
189
Found in the Anteroventral eall of 3rd Ventricle & Preoptic Nuclei
Thirst Center
190
Control of Thirst: Increased thirst
Increase Osmolarity, AngiotensinDecrease Blood Volume, BPDryness of mouth
191
Control of Thirst: Decreased thirst
Increased Blood Volume, BPDecreased Osmolarity, Angiotensin IIGastric Distention
192
Found in the pons
Micturition Center
193
Micturition Center can be inhibited by
Cerebral Cortex
194
Normal Plasma H
0.00004mEq/L
195
Normal Plasma pH
7.4
196
Systems that regulate H concentrations
Body Fluid Buffer SystemsRespiratory CenterKidneys
197
Mechanisms of Renal Regulation of Acid-Base Balance
Secretion of HReabsorption of filtered HCO3Production of new HCO3
198
Due to Decreased Ventilation
Respiratory Acidosis
199
Due to Increased Ventilation
Respiratory Alkalosis
200
Due to excess acid or loss of base
Metabolic Acidosis
201
Due to loss of acid or gain of base
Metabolic Alkalosis
202
Decreased HCO3; Increased Organic Anions to maintain electroneutrality
High Anion Gap Metabolic Acidosis (HAGMA)
203
Decreased HCO3; Increased Chloride to maintain electroneutrality; Also called Hyperchloremic Metabolic Acidosis with Normal Anion Gap
Normal Anion Gap Metabolic Acidosis (NAGMA)
