Exam 1: Renal Physiology (Lectures 1-3) Flashcards
1
Q
What are the five renal functions?
A
1) RBC Synthesis
2) H2O and Electrolyte Balance
3) Excrete Metabolic Wastes and Foreign Chemicals
4) Regulate Arterial Blood Pressure via RAAS
5) Vit D Production
2
Q
Total body water gain is primarily accomplished by the _______ while Total body water loss primarily occurs through the _____
A
ingestion of liquids and foods; through the kidneys
3
Q
The primary mechanism regulating body water is the ___, which drives thirst, and the _____, which set the rate of urinary excretion
A
CNS; kidneys
4
Q
A
5
Q
True or False: Kidneys produce renin, aldosterone, angiotensinogen, and erythropoietan
A
False - kidneys produce
1) renin
2) aldosterone
3) erythropoietan
6
Q
True or False: The kidney is an exocrine organ
A
False - kidney is an endocrine organ
7
Q
How will erythropoietan be affected by a decrease in blood oxygen delivery to the kidneys?
A
Erythropoietan levels will be increased
8
Q
True or False: Renal pathophysiology may result in anemia
A
True
9
Q
The kidneys use 1-alpha-hydroxylase (proximal tubule) to convert ____ into the active hormone ____.
A
Vit D3; Calcitriol
10
Q
True or False: Calcitriol increases calcium, magnesium, and phosphate absorption in the intestines
A
True
11
Q
True or False: During prolong fasting, the kidneys are able to make glucose from amino acids
A
True
12
Q
Where does urine formation begin?
A
Glomerular capillaries
13
Q
Urinary Excretion = ?
A
Filtration - Reabsorption + Secretion
14
Q
True or False: Reabsorption can be passive or active
A
True
15
Q
If the concentration of a substance is greater in the urine than in the filtrate, what does this suggest happened to the filtrate?
A
It was filtered and secreted
16
Q
The [of any substance] in the urine depends on:
1)
2)
3)
A
1) serum concentration
2) ratio of filtration:reabsorption:secretion
3) rate of water reabsorption
17
Q
To assess renal function, measure the concentration of the substance in the ____, ____, as well as the _____ rate
A
urine, blood, and urinary flow rate
18
Q
What structures make up the “filtration unit” of the kidney?
A
Renal Corpuscle
(Glomerulus + Bowman’s capsule)
19
Q
The reabsorption and secretion units of the nephron are the ____ and the ____
A
tubules; blood vessels
20
Q
True or False: The tubule is composed of the Proximal Convoluted Tubule, Loop of Henle, Distal Tubule, and Collecting Duct
A
True
21
Q
Which nephrons barely dip into the medulla?
A
Cortical nephrons
22
Q
What is the peritubular capillary network in Juxta-medullary nephrons known as?
A
vasa recta
23
Q
True or False: The Loop of Henle in Juxta-Medullary Nephrons dips deep into the medulla
A
True
24
Q
Blood flow in the vasa recta contributes to the hypertonic medulla, as high ___ can wash out the medulla
A
flow rate
25
The glomerulus is supplied by ___ and drained by ___
afferent arteriole; efferent arterioles
26
The glomerular capillaries contain ____, or windows, that facilitate filtration
fenestrations
27
___ surrounds glomerular capillaries
Podocytes
28
________: collects the filtrate from the capillaries and directs it to the proximal tubule
Bowman's Capsule
29
Which tubule in the nephron reduces volume of filtrate by reabsorbing ~2/3rd of water and majority of nutrients?
Proximal Convoluted Tubule
30
The thin descending limb is water _____ and the thick ascending limb is water _____
permeable; impermeable
31
The ionic gradient established by the Na/K/2Cl in the ______ is used to reabsorb ___ from the _____
Thick ascending limb
water; collecting duct
32
______ returns and runs adjacent to the originating glomerulus, providing feedback
Distal Convoluted Tubule
33
True or False: Distal convoluted tubule regulates reabsorption of water
False - ions
34
Where does ADH (AVP) act?
Collecting Tubule/System
35
Two major cell types in collecting tubule + their functions?
Principal Cells: Reabsorbs water and salt by secreting K into lumen
Intercalated Cells: Reabsorbs K by secreting H
36
____: the structure located at intersection of distal tubule and afferent/efferent arterioles.
Juxtaglomerular Apparatus (JGA)
37
Where is the primary site for renin release?
JGA Apparatus
38
What cell types are found in the distal tubule?
A. Squamous epithelia
B. Cuboidal epithelia
C. Columnar epithelia
B. Cuboidal epithelia
39
40
What are the types of receptors/cell types present in the afferent arteriole?
Baroreceptors
Granular cells
41
Where are osmoreceptors found in the JGA?
A. Distal Tubule
B. Afferent Arterioles
C. Efferent Arterioles
A. Distal Tubule
42
___ contains renin vesicles
A. Granular Cells
B. Macula Densa
C. Osmoreceptors
A. Granular Cells
43
Mesangial cells help regulate GFR via: secretion of what two molecules?
A. NO and NE
B. Cyotokines and Prostaglandins
C. Renin
What type of cells regulate capillary blood flow and the surface area for filtration?
B. Cyotokines and Prostaglandins
Endothelial cels
44
Deposition of immune complexes in the _____
triggers an inflammatory response, which can lead to glomerular scarring (sclerosis)
and loss of glomerular function
A. Distal Tubule
B. Mesangium
C. Afferent Arteriole
D. Efferent Arteriole
B. Mesangium
45
True or False: The JGA
regulates systemic volume and blood pressure by releasing renin into the circulation
True
46
True or False: The Juxtaglomerular Apparatus in each nephron regulates its own capillary
permeability and arteriole resistance which
establishes the pressure gradient for GFR.
True
47
What three structures make up the glomerular filtration barrier?
1) Endothelium
2) Basement Membrane
3) Podocytes and Slit Diaphragm
note: all of these are negative
48
The glomerular capillary barrier serves as a filter based on ____ and ___
molecular size and charge
49
Pore in the slit diaphagm pass ___ and ____ but selectively restrain medium (albumin) to large proteins (IgG)
water; electrolytes
50
Molecules that are LESS than __ A in radius can easily pass through the glomerular barrier
20 A
51
Examples of molecules that are less than 20 A in radius (and, therefore, can easily pass through the glomerular barrier)
1) Urea
2) Water
3) Electrolytes
4) Glucose
5) B2-microglobulin
52
Molecules ranging between ___ A are limited by the molecular size and their ____
20-42 A
charge
53
Same sizes molecules with a ___ charge have higher filtration rates
positive
54
How does neutralization of glomerular barrier affect filtration of plasma protein?
Neutralization of glomerular barrier increases filtration of plasma protein
55
56
In a normal healthy kidney, molecules larger than __A are restricted by size
42 A
57
Despite having a radius of 36A, albumin is unable to pass through the glomerular filter. Why?
Albumin is negatively charged, which reduces its permeability
58
What are the major regulators of renal blood flow and filtration rate?
A. Vasa recta
B. Proximal Tubule
C. Afferent/Efferent Arterioles
C. Afferent/Efferent Arterioles
59
How is hydrostatic pressure required for filtration obtained?
The afferent/efferent arterioles ensure there is high pressure within the glomerular capillary bed
60
The efferent arteriole branches to form _____
peritubular capillaries
61
True or False: Peritubular capillaries have high capillary pressure and low oncontic pressure
False - peritubular capillaries have normal capillary pressure and high oncontic pressure
62
Why do the peritubular capillaries have high oncotic pressure?**
Due to loss of protein free filtrate in glomerulus
63
What is normal Pgc and Pbc value?
Pgc = 55 mmHg
Pbc = 15 mmHg
64
What is the pressure gradient for filtration?
40 mmHg
(Pg-Pbc)
(55-15)
65
True or False: Proteins create a concentration gradient for the movement of water and will "pull" water into that compartment
True
66
____ pressures oppose hydrostatic pressure
Colloid Osmotic Pressure
67
What is the pressure gradient that opposes filtration?
= 30 mmHg pressure gradient that opposes filtration
(30-0)
(GC Oncotic Pressure) - (BC Oncotic Pressure)
68
How do you calculate Net Filtration Pressure?
69
Under normal conditions, the net pressure for filtration is:
A. 10 mmHg
B. 15 mmHg
C. 30 mmHg
D. 35 mmHg
A. 10 mmHg
70
_____: the measure of a membrane's permeability to water. It is the product of the SA and permeability to water.
Filtration Coefficient (Kf)
71
Normal Kf value? GFR?
Kf = 12.5
GFR = 125
72
Capillary pressure will be opposed by inward ____ in bowman's capsule
hydrostatic pressure
73
When the plasma is filtered into Bowman's Space, there is/is not proteins
is not
(as a result oncotic pressure in Bowman's Space =0)
74
When the plasma is filtered and proteins are left in the capillaries, the abundance of proteins increases ___ pressure in the ____
capillaries
75
In a healthy person, ___ is regulated by tone of afferent and efferent arterioles
A. RBF
B. GFR
C. RAAS
GFR
76
Under normal physiological conditions, GFR is regulated by changing:
A. Pbc
B. Pgc
C. Oncotic gc
D. Oncotic bc
B. Pgc
77
How are renal blood flow (RBF), Pgc (glomerular capillary hydrostatic pressure) and GFR affected by constriction/dilation of efferent arteriole?
78
True or False: If 100% of substance is bound to protein, it will be filtered
False - it will NOT be filtered
79
_____: Avoids swings in arterial pressure, maintains RBF and GFR
Autoregulation
80
The autoregulatory range is ~
A. 20-40 mmHg
B. 50-100 mmHg
C. 60-120 mmHg
D. 90-180 mmHg
D. 90-180 mmHg
81
GFR and RBF remain
relatively constant over an
arterial pressure range of
_____
~90-180 mmHg
82
Below __ mmHg, RBF and
GFR will follow arterial
pressure.
90 mmHg
83
How do mesangial cells regulate GFR?
A. Induce arteriole contraction via Angiotensin II/Endothelin
B. Induce arteriole contraction via NO and PE
C. Induce arteriole relaxation via PGE2
A. Induce arteriole contraction via Angiotensin II/Endothelin
C. Induce arteriole relaxation via PGE2
84
True or False: Sympathetic nerves innervate both arterioles and are tonically active at low levels
True
85
A fall in blood pressure, fear, pain, heavy exercise, etc. activates the sympathetic nervous system.
Does activation of sympathetic nervous system affect the afferent or efferent arteriole?
Activation of Sympathetic Nervous System causes constriction of AFFERENT arteriole, leading to decrease in RBF and GFR
86
True or False: Renin release and formation of Angiotensin I is induced by high ECF volume and low renal perfusion pressure
False - Renin release/formation of Angiotensin I is induced by decreased ECF volume as well as low renal perfusion pressure)
87
What structure is found in the afferent arteriole to sense pressure?
A. Osmoreceptor
B. Baroreceptor
C. Sympathetic Nerves
What is release by afferent arteriole in response to decrease in blood pressure?
B. Baroreceptor
Renin
88
True or False: Beta-1 agonists (like NE and Epinephrine) inhibit renin release
False - Beta-1 agonists (like NE and Epinephrine) increase renin release
89
The macula densa cells of the distal tubule are activated in response to:
A. volume depletion and Osm changes
B. elevated volume and decrease Osm
C. stress/anxiety
A.
90
Ang II supports GFR when ___ decreases
Renal plasma flow (RPF)
91
True or False: AT2 receptors predominate and are responsible for systemic vasoconstriction
False - AT1 receptors predominate and
are responsible for systemic vasoconstriction (increases TPR and BP)
92
Ang II has a preferential effect on which arteriole?
When Ang II acts on Efferent Arteriole, how are GFR/RPF/systemic blood pressure affected?
Efferent Arteriole
GFR/RPF/systemic BP become elevated
93
True or False: AngII induced constriction of the efferent arteriole preserves GFR and renal function
True
94
Angiotensin II also selectively promotes the reabsorption of what two molecules to further increase water volume and blood pressure?
A. Na and Cl
B. Na and H2O
C. Na and K
D. renin and aldosterone
B. Na and water
95
What cells of the kidney generate NO?
Endothelial cells
96
Which arteriole does NO preferentially dilate to maintain GFR and renal blood flow?
The Afferent Arteriole
97
What would occur if NO were inhibited?
-Increased basal tone
-Enhanced vasoconstriction
-Reduced GFR
-Reduced renal blood flow
98
Where do vasodilatory prostaglandins preferentially act?
A. Macula densa cells
B. Efferent Arteriole
C. Baroreceptors
D. Afferent arteriole
D. Afferent Arteriole
99
What conditions stimulate vasodilatory prostaglandin production?
1) Decreased ECF volume
2) Angiotensin II
3) sympathetic nerves
4) Stress/surgery
100
How do prostaglandins —especially
PGI2—prevent harmful degrees of vasoconstriction, which would otherwise cause renal ischemia?
Prostaglandins —e.g PGI2— cause vasodilation, thereby counteracting the vasoconstrictor effects of catecholamines and angiotensin II
101
Inhibition of PGs will cause unopposed constriction of which arteriole?
Afferent Arteriole
102
Bradykinin is a vasodilator that works by stimulating the release of what two molecules from endothelial cells?
Nitric oxide and prostaglandins
103
How do bradykinins (vasodilator) affect GFR and RBF?
Increase GFR and RBF
104
Since ACE breaks down bradykinin, part of the BP-lowering and renal vasodilatory effects of ACE inhibitors are attributed to enhanced
___ levels.
bradykinin
105
Are thromboxane and PGF2α vasodilators and vasoconstrictiors?
Vasoconstrictors
106
Why is the transcellular movement of water (in response to osmotic pressure) so high in the proximal tubule?
Aquaporins
107
AQP-1 is present in the _____ while AQP-2 is found in the _____.
proximal tubule; collecting duct
108
How does the proximal tubule increase the
SA for transport mechanisms and reabsorption?
A. Microvilli in apical membrane and folds in the the basolateral membrane
B. Microvilli in the basolateral membrane and folds in the aplical membrane
A. Microvilli in apical membrane and folds in the the basolateral membrane
109
True or False: There are aquaporin channels in both the apical and basolateral
membranes of the PCT
True
110
Where are the tight-leaky junctions of the proximal convoluted tubule located?
Apical surface
111
In the proximal tubule, cells have a high
conductance for small ions resulting in high ______
para-cellular permeability
112
___ of filtered NaCl, K, and water are reabsorbed in the proximal tubule
__ of urea and __ of glucose and amino
acids are reabsorbed.
__ of bicarbonate
is “recovered” in the proximal tubule
65%
50%
100%
90%
113
Why is there a minimal change in ionic concentrations or osmotic pressure in the proximal convoluted tubule?
There's a combined transport of solutes AND water
114
Why does the proximal convoluted tubule only generate small concentration gradients?
A. High permeability
B. Small gradients
C. Low Ena
A. High permeability
115
True or False: The thin descending limb is made of squamous epithelial and minimal mitochondria, suggesting no active transport occurs here.
True
116
What cell type is the thick ascending limb made of?
A. Squamous
B. Columnar
C. Cuboidal
C. Cuboidal
117
In addition to the proximal convolute tubule, which other tubule contains
folds on the surface of the basolateral
membrane to increase surface area?
Thick ascending limb
118
Where is the Na/K/2Cl Co-transporter located?
Thick ascending limb
119
Reabsorption is dependent upon the activity of the basolateral Na/K ATPase in the thick ascending limb, since it creates the electrochemical gradient for the reabsorption of what three molecules?
Na, K and Cl
120
True or False: Both the thin and thick ascending limbs are impermeable to water
True
121
The _______ is a zone for transition and feedback to the juxtaglomerular
apparatus.
The distal tubule
122
What two molecules are primarily reabsorbed in the Distal Tubule via co-transporters?
Na, Cl
via: secondary active transport
123
Which co-transporter does a thiazide diuretic block?
A. Na/K ATPase
B. Na-Cl Co Transporter
C. Na/K/2Cl Transporter
D. ADH
B. Na-Cl Co Transporter (distal convoluted tubule)
124
True or False: Water permeability in the distal tubule is dependent upon the presence of antidiuretic hormone
True
125
In the Collecting Duct, Na reabsorption is driven by a transporter located on the basolateral membrane. Namely:
A. Na-Cl Co Transporter
B. ADH
C. Na/K/2Cl
D. Na/K ATPase
D. Na/K ATPase
126
What are the Na channels located on the apical membrane of Principal Cells of the Collecting Tubule Na reabsorption called?
Epithelial Na Channels
(ENaC)
127
Epithelial Na Channels
(ENaC) work in
conjunction with apical K channels, which leads to __ reabsorption and __ excretion
Na ; K
128
How does aldosterone promote K
secretion?
A. Regulates number and conductance of ENaC
B. Regulates number of open apical K+ channels
B. Regulates number of open apical K+ channels
129
How does aldosterone promote Na reabsorption?
A. Regulates number and conductance of ENaC
B. Regulates number of open apical K+ channels
A. Regulates number and conductance of ENaC in CT
130
What is the overall effect that aldosterone has on ions?
1) Retention of Na → Cl and water
2) Loss of K+.
131
Which receptors do potassium-sparing diuretics (such as Amiloride) block?
A. Na/K ATPase
B. ENaC
C. Na/K/2Cl
B. ENaC
-on the apical membrane on Principal Cells of the CT
132
Spironolactone can be used to block which molecule?
A. renine
B. aldosterone
C. K
B. aldosterone
thereby regulating Na/K
exchanger in the collecting tubules.
133
What do Type A Intercalated cells secrete?
A. H+
B. HCO3
C. H-
What do Type A Intercalated cells generate?
A. H+
B. HCO3
C. H-
A. H+
B. HCO3
134
What do Type B Intercalated cells secrete?
A. H+
B. HCO3
C. H-
What do Type B Intercalated cells generate?
A. H+
B. HCO3
C. H-
B. HCO3
A. H+
135
What is the primary driving force for tubule reabsorption?
A. Na-K ATPase
B. Na-K-2Cl
A. Na-K ATPase
136
True or False: Basolateral entry of sodium from lumen into tubular cells is driven by electrochemical gradient for sodium made by apical Na/K ATPase
False - Apical entry of sodium from lumen into tubular cells is driven by electrochemical gradient for sodium made by basolateral Na/K ATPase
137
Sodium reabsorption occurs via:
A. Active transport
B. Passive diffusion
B. Passive diffusion
138
Where is the Na-H exchanger located?
A. Proximal tubule
B. Loop of Henle
C. Distal Tubule
D. Collecting Duct
A. Proximal Tubule
139
What drives the Na-H exchanger?
A. Sodium chemical gradient
B. Osmotic gradient
C. H gradient
D. Diffusion
A. Sodium chemical gradient
140
Which Na-Symporters are found in the proximal tubule?
A. glucose, amino acids, phosphate, calcium, lactate
B. maltose, hydroxide, anaphylatoxins
C. fructose, nucleotides, and deoxynucleotides
A. glucose, amino acids, phosphate, calcium, lactate
141
Where is ~2/3 of sodium reabsorbed?
Proximal tubule
142
Where is the apical Na/K/2Cl located?
A. Proximal Tubule
B. Thin descending limb
C. Thick ascending limb
D. Collecting Duct
C. Thick ascending limb
143
True or False: Na/K/2Cl is important for establishing salty medulla
True
144
True or False: Osmotic gradient drives water reabsorption from collecting duct in the absence of ADH
False - Osmotic gradient drives water reabsorption from collecting duct when ADH is present
145
Where is 25% of Na reabsorbed?
A. Proximal Tubule
B. Thick ascending limb
C. Thin descending limb
D. Collecting Duct
B. Thick ascending limb
146
What two transporters contribute to sodium reabsorption in the distal convoluted tubule?
A. Na/K ATPase
B. ENaC
C. Na/Ca2+ symporter
D. Na/Cl-
C. Na/Ca2+ symporter
D. Na/Cl-
147
What channel do principal cells use to reabsorb sodium? What is this channel regulated by? How is sodium reabsorption achieved?
ENaC
Aldosterone
At expense of losing K
148
Where is the Na-Glucose Co-Transporter located? What is it driven by?
Proximal tubule (apical membrane)
- Drive by EC gradient for sodium
149
Amino acids are reabsorbed by a ___ symporter
Sodium
150
How is water reabsorbed?
A. Osmotic gradients created by active transport mechanisms
B. Active transport
C. Na/Cl/K Co-transporters
A. Osmotic gradients created by active transport mechanisms
151
True or False: The active transport of sodium out of cells creates an electrical gradient for the reabsorption of Cl-
True
152
As water leaves the lumen, does the ion concentration in the tubular filtrate increase or decrease?
Increase
Increased concentration gradient favors diffusion out of lumen and into interstitial fluid
153
True or False: When additional water is reabsorbed, the solutes in water are carried along
True
154
True or False: Diffusion and co-transport of Cl- creates a negative charge in the interstitial fluid, which est. an electrical gradient for passive diffusion of cations (K, Ca, Mg)
True
155
What will happen if active reabsorption of sodium occurs in the absence of water reabsorption?
Na will move down concentration gradient back into tubular lumen
156
What is a major mechanism for total body K regulation?
Renal K excretion (takes hrs!)
157
What three hormones help regulate extracellular concentration of K?
1) Insulin
2) Epinephrine
3) Aldosterone
158
Does Insulin more K into cells or out of cells?
Into cells
159
How can hyperkalemia be treated?
Insulin + glucose IV
160
How does epinephrine promote K uptake and K release?
A-adrenoceptors -> releases of K from liver cells
Beta-2 adrenoceptors -> uptake of K.
161
How does aldosterone promote hypokalemia?
Promotes K+ excretion in kidney - in exchange for Na/H2O reabsorption
162
Like Na, the kidneys reabsorb K in the
A. Proximal Convoluted Tubule and Loop of Henle
B. Collecting Duct and Thin Ascending Limb
C. Collecting Duct and Thick Ascending Limb
C. Collecting Duct and Thick Ascending Limb
163
Secretion of K occurs in the
________ via
principal cells
distal collecting tubules
164
High dietary intake of K
results in:
A. Reabsorption
B. Filtration
C. Secretion
C. Secretion
165
Low dietary intake of K
results in:
A. Reabsorption
B. Filtration
C. Secretion
D. Excretion
A. Reabsorption
166
Lack of aldosterone often results in which condition?
A. Hyperkalemia
B. Hypokalemia
C. Hypernatremia
D. Hyponatremia
A. Hyperkalemia
167
What are the two primary regulators of K
secretion?
Aldosterone and Plasma K+
168
When a ______ is used to move a solute a maximal rate of transport exists because there is a maximal number of binding site
co-transporter
169
The Tm (max transport) for glucose is 375mg/min. If the filtered
load is 400 mg/min, will glucose be present in the urine?
Since the filtered load exceeds Tm, the solute will begin to appear in the urine !
170
__: represents the max resorptive capacity of the proximal tubule
Maximal Rate of Transport
171
If delivery of the solute to the peritubular capillaries exceeds the Tm secretion rate for
that substance, then the remainder will be remain in the ____
circulation
172
True or False: Hormones and drugs that bind to serum proteins have a longer half-life because the proteins are not filtered
True
