Uni Week 2 Flashcards
(207 cards)
1
Q
What is the structure of the capillary tuft in the glomerulus?
A
15–20 looping
2
Q
What are the components of the filtration barrier in the glomerulus?
A
Fenestrated endothelium
3
Q
What is the function of the fenestrated endothelium in the glomerulus?
A
Repels cells and large proteins
4
Q
What are the layers of the glomerular basement membrane (GBM)?
A
Lamina rara interna
5
Q
What proteins are involved in the formation of slit diaphragms in podocytes?
A
Nephrin
6
Q
What is the role of the mesangium in the glomerulus?
A
Provides structural support
7
Q
True or False: The glomerular basement membrane contains type IV collagen.
A
t
8
Q
Fill in the blank: The primary processes of podocytes interdigitate to form _______.
A
slit diaphragms
9
Q
What type of epithelium is found in the Proximal Convoluted Tubule (PCT)?
A
Tall cuboidal
10
Q
What are the major functions of the Proximal Convoluted Tubule (PCT)?
A
Bulk reabsorption of Na⁺
11
Q
What is the structure of the epithelium in the Thin Limbs of Henle?
A
Simple squamous
12
Q
What is the major function of the Thin Limbs of Henle?
A
Passive NaCl or H₂O flux (depending on limb)
13
Q
What type of epithelium is found in the Thick Ascending Limb (TAL)?
A
Cuboidal with apical microprojections
14
Q
What are the major functions of the Thick Ascending Limb (TAL)?
A
Active Na⁺-K⁺-2Cl⁻ reabsorption; impermeable to water
15
Q
What type of epithelium is found in the Distal Convoluted Tubule (DCT)?
A
Low cuboidal
16
Q
What are the major functions of the Distal Convoluted Tubule (DCT)?
A
NaCl reabsorption (NCC)
17
Q
What type of cells are found in the Cortical Collecting Duct?
A
Principal + intercalated cells
18
Q
What is the major function of the Cortical Collecting Duct?
A
Water & Na⁺ balance
19
Q
What is the structure of the epithelium in the Medullary Collecting Duct?
A
Increasing columnar height
20
Q
What is the major function of the Medullary Collecting Duct?
A
Final urine concentration
21
Q
What is the JGA?
A
A specialised nephron–vascular interface at the vascular pole
22
Q
What are the main components of the JGA?
A
Macula densa
23
Q
Describe the macula densa.
A
30–40 closely packed NaCl-sensing DCT cells; tall with dark nuclei; communicate via gap junctions.
24
Q
What type of cells are juxtaglomerular (granular) cells?
A
Modified smooth-muscle cells in the afferent (± efferent) arteriole wall; contain renin granules.
25
Where are extraglomerular mesangial (Lacis) cells located?
Between macula densa and arterioles
26
What is the function of extraglomerular mesangial (Lacis) cells?
Transmit signals and may contain renin in neonates.
27
True or False: Juxtaglomerular cells are found in the efferent arteriole.
t
28
Fill in the blank: The macula densa cells are responsible for sensing _______.
[NaCl]
29
What is Tubuloglomerular feedback (TGF)?
A mechanism where ↑NaCl at macula densa causes ATP/adenosine release
30
What happens when NaCl levels decrease in TGF?
NO/PGI₂ release occurs
31
What role do granular cells play in renin release?
Granular cells act as renal baroreceptors
32
What initiates the renin-angiotensin-aldosterone system (RAAS)?
Renin release from granular cells.
33
How do Lacis cells contribute to nephron function?
They propagate Ca²⁺ waves
34
Fill in the blank: TGF involves the release of _______ and adenosine.
ATP
35
True or False: A decrease in NaCl at the macula densa leads to afferent arteriolar vasoconstriction.
36
What is the effect of ↑NaCl levels at the macula densa?
Afferent arteriolar vasoconstriction and ↓GFR.
37
What is the Starling equation used for in the context of filtration?
It describes the driving forces of filtration in the kidneys.
38
What does the variable Kf represent in the Starling equation?
Hydraulic permeability × surface area.
39
What factors determine permselectivity during molecular movement?
Size
40
What size of molecules can pass through the filtration barrier?
Molecules with a radius of less than 4 nm.
41
Which type of charge has the highest permeability in filtration?
Cationic.
42
List the factors that increase filtration.
↑ glomerular capillary hydrostatic pressure
43
What effect does afferent dilation have on filtration?
It increases glomerular capillary hydrostatic pressure.
44
What happens to filtration when there is relief of urinary tract obstruction?
Bowman’s space hydrostatic pressure decreases.
45
What condition leads to a decrease in plasma oncotic pressure?
Hypoproteinaemia.
46
How does mesangial relaxation affect Kf?
It increases Kf.
47
Fill in the blank: The Starling equation for glomerular filtration rate is J˙GFR = Kf [(P_GC − P_BS) − σ(π_GC − ______)].
π_BS
48
What is the definition of Glomerular Filtration Rate (GFR)?
Volume of plasma filtered per minute by all functioning glomeruli (~125 mL min⁻¹
49
What are the two components of autoregulation of GFR?
Myogenic response (intrinsic smooth-muscle stretch)
50
What is the role of Angiotensin II (Ang II) in GFR control?
Constriction of efferent > afferent arterioles—maintains GFR when renal perfusion falls.
51
How do ANP and BNP affect GFR?
They dilate afferent arterioles and relax mesangium
52
What is the impact of ADH on GFR?
Mild vasoconstriction via V₁; minor impact on GFR.
53
What is the effect of sympathetic α₁ stimulation on GFR?
Intense vasoconstriction of both arterioles (predominantly afferent)
54
What is the formula for flow–pressure–resistance?
Q = ΔP / R
55
What does Q represent in the flow–pressure–resistance formula?
Flow (renal blood flow)
56
What does ΔP represent in the flow–pressure–resistance formula?
Pressure gradient (mean arterial – venous)
57
What does R represent in the flow–pressure–resistance formula?
Vascular resistance
58
Fill in the blank: In the formula Q = ΔP / R
Q stands for _______.
59
Fill in the blank: In the formula Q = ΔP / R
ΔP represents the _______.
60
Fill in the blank: In the formula Q = ΔP / R
R denotes _______.
61
What effect does increased afferent tone have on Renal Blood Flow (RBF)?
Decreases RBF
62
What happens to Glomerular Hydrostatic Pressure (P) when afferent tone is increased?
Decreases Glomerular Hydrostatic Pressure
63
What is the impact on Glomerular Filtration Rate (GFR) with increased afferent tone?
Decreases GFR markedly
64
What effect does decreased afferent tone have on Renal Blood Flow (RBF)?
Increases RBF
65
What happens to Glomerular Hydrostatic Pressure (P) when afferent tone is decreased?
Increases Glomerular Hydrostatic Pressure
66
What is the impact on Glomerular Filtration Rate (GFR) with decreased afferent tone?
Increases GFR
67
What effect does increased efferent tone have on Renal Blood Flow (RBF)?
Decreases RBF
68
What happens to Glomerular Hydrostatic Pressure (P) when efferent tone is increased?
Increases Glomerular Hydrostatic Pressure proximal to constriction
69
What is the impact on Glomerular Filtration Rate (GFR) with increased efferent tone?
Biphasic: moderate increase
70
What effect does decreased efferent tone have on Renal Blood Flow (RBF)?
Increases RBF
71
What happens to Glomerular Hydrostatic Pressure (P) when efferent tone is decreased?
Decreases Glomerular Hydrostatic Pressure
72
What is the impact on Glomerular Filtration Rate (GFR) with decreased efferent tone?
No significant change
73
What are the types of tubular transport?
Primary active
74
What is an example of primary active transport?
Na⁺/K⁺-ATPase
75
What are the two types of secondary active transport?
Symporters and antiporters
76
Name two examples of symporters involved in secondary active transport.
SGLT
77
Give two examples of antiporters involved in secondary active transport.
NHE3
78
What is facilitated diffusion?
Transport of substances down their concentration gradient via specific transport proteins
79
Name two transporters involved in facilitated diffusion.
GLUT1
80
What is paracellular solvent drag?
Transport of water and solutes through tight junctions between cells
81
What is the role of endocytosis in tubular transport?
Protein reabsorption via megalin–cubulin in PCT
82
What is the route for transcellular transport?
Across apical membrane → cytosol → basolateral membrane
83
What is the route for paracellular transport?
Through tight-junction limits
84
What determines the selectivity of transcellular transport?
Transporter/ channel dependent
85
What determines the selectivity of paracellular transport?
Claudin composition; size/charge-selective
86
Does transcellular transport require energy?
May require active steps
87
Is paracellular transport passive or active?
Passive
88
What is the typical intracellular concentration range of Na⁺?
10–15 mmol L⁻¹
89
What is the typical extracellular concentration range of Na⁺?
135–145 mmol L⁻¹
90
What is the typical intracellular concentration range of K⁺?
120–150 mmol L⁻¹
91
What is the typical extracellular concentration range of K⁺?
3.5–5.0 mmol L⁻¹
92
What is the typical intracellular concentration of phosphate (HPO₄²⁻/H₂PO₄⁻)?
75 mmol L⁻¹
93
What is the typical extracellular concentration range of phosphate (HPO₄²⁻/H₂PO₄⁻)?
1–2 mmol L⁻¹
94
What is the typical intracellular concentration of free Ca²⁺?
0.0001 mmol L⁻¹
95
What is the typical extracellular concentration range of free Ca²⁺?
1.1–1.3 mmol L⁻¹
96
What is the typical intracellular concentration of Mg²⁺?
12 mmol L⁻¹
97
What is the typical extracellular concentration of Mg²⁺?
0.8 mmol L⁻¹
98
What is the role of aquaporin-1 (AQP1) in the descending thin limb?
Highly abundant; water exits passively
99
What is the permeability of the ascending thin and thick limbs to water?
Impermeable to water
100
What happens in the DCT and cortical collecting duct regarding water permeability?
Baseline water impermeable; ADH inserts AQP2 apically for facultative reabsorption
101
What effect does ADH have on the inner-medullary collecting duct?
Increases water and urea permeability (via UT-A1/3)
102
Fill in the blank: The descending thin limb is highly abundant in _______.
aquaporin-1 (AQP1)
103
True or False: The ascending limbs of the nephron are permeable to water.
104
What type of epithelium is described?
Tall
105
What structural feature is prominent in the described epithelium?
Prominent microvilli (brush border)
106
What is the function of the basolateral labyrinth in the epithelium?
Supports transport and absorption processes
107
What cellular component is abundant in the described epithelium?
Numerous elongated mitochondria
108
What does the presence of numerous elongated mitochondria indicate?
High ATP demand
109
What does SGLT stand for?
Na⁺-Glucose Symport
110
What is the Na⁺ to glucose ratio for SGLT2?
1 Na⁺ : 1 glucose
111
What is the primary function of SGLT2?
Accounts for 90% of reabsorbed glucose
112
What type of affinity and capacity does SGLT2 have?
Low affinity/high capacity
113
What is the Na⁺ to glucose ratio for SGLT1?
2 Na⁺ : 1 glucose
114
What type of affinity does SGLT1 have?
High affinity
115
What is the role of SGLT1 in glucose reabsorption?
Clears residual glucose
116
How does glucose exit basolaterally for SGLT2?
Via GLUT2
117
How does glucose exit basolaterally for SGLT1?
Via GLUT1
118
What does the Na⁺-H⁺ Antiporter (NHE3) exchange?
Exchanges luminal Na⁺ for intracellular H⁺
119
How does NHE3 contribute to HCO₃⁻ reclamation?
Via carbonic anhydrase IV/II
120
What role does NHE3 play in ammonium trapping?
Contributes to ammonium trapping by substituting NH₄⁺ for H⁺
121
What percentage of filtered water is reabsorbed isosmotically in the PCT?
Around 65%
122
What is osmotic diuresis?
A condition where unreabsorbed solute raises tubular osmolarity
123
Fill in the blank: Around 65% of filtered water follows solute isosmotically in _______.
PCT
124
True or False: AQP1 is involved in the reabsorption of water in the PCT.
t
125
What role do leaky tight junctions play in water reabsorption?
They allow water to follow solute isosmotically in the PCT
126
What happens to water during osmotic diuresis?
It is held in the tubule due to increased tubular osmolarity
127
What is Fanconi Syndrome?
A disorder characterized by generalized proximal tubular dysfunction of the kidneys.
128
What are the inherited causes of Fanconi Syndrome?
Cystinosis
129
What are drug-induced causes of Fanconi Syndrome?
Ifosfamide
130
What heavy metals can cause Fanconi Syndrome?
Heavy metals (specific metals not listed).
131
Which condition associated with multiple myeloma can lead to Fanconi Syndrome?
Myeloma light chains.
132
What are the clinical features of Fanconi Syndrome?
Polyuria
133
What is a significant laboratory finding in Fanconi Syndrome?
Generalized PCT transport defect.
134
What is glucosuria with normal glycaemia indicative of in Fanconi Syndrome?
Proximal renal tubular acidosis (PCT transport defect).
135
What are the types of urinary losses in Fanconi Syndrome?
Phosphaturia
136
What is a common finding in the histology of PCT cells in Fanconi Syndrome?
Vacuolization and mitochondrial swelling.
137
What are the main components of treatment for Fanconi Syndrome?
Replace losses (oral phosphate
138
What does the prognosis of Fanconi Syndrome depend on?
Underlying etiology.
139
Fill in the blank: Fanconi Syndrome can lead to ______ due to renal tubular dysfunction.
growth failure
140
What are the transporters involved in glucose reabsorption?
SGLT2/1 (apical)
141
What is the transport maximum (Tₘ) for glucose reabsorption?
~375 mg min⁻¹
142
What happens when the transport maximum for glucose is exceeded?
Glucosuria
143
How are amino acids reabsorbed in the kidneys?
Through multiple Na⁺-dependent symporters grouped by side-chain class
144
Fill in the blank: The reabsorption of glucose in the kidneys involves _______ transporters.
[SGLT2/1 and GLUT2/1]
145
True or False: Amino acids are reabsorbed completely in the kidneys.
t
146
What type of cells are found in thin limbs?
Simple squamous cells with flattened nuclei
147
What is the histological structure of the thick ascending limb (TAL)?
Cuboidal cells
148
What transporters are located at the apical membrane of the thick ascending limb (TAL)?
NKCC2 and ROMK
149
What are the basolateral transporters found in the thick ascending limb (TAL)?
ClC-Kb/Barttin and Na⁺/K⁺-ATPase
150
What does NKCC2 stand for?
Na⁺-K⁺-2Cl⁻ Symporter
151
What ions does NKCC2 transport?
1 Na⁺
152
How does K⁺ recycling affect the lumen voltage?
Creates positive lumen voltage
153
What is the role of ROMK in relation to NKCC2?
K⁺ recycling
154
Fill in the blank: NKCC2 couples the entry of _______.
1 Na⁺
155
True or False: NKCC2 is involved in the reabsorption of potassium ions only.
156
What does the positive lumen voltage facilitate?
Paracellular Ca²⁺/Mg²⁺ reabsorption
157
What is the single-effect in the generation of medullary osmotic gradient?
TAL reabsorbs NaCl without water → interstitium hypertonic.
158
Define counter-current multiplication in the context of medullary osmotic gradient.
Continuous flow converts horizontal to vertical gradient (300 → 1200 mOsm).
159
What is the role of urea recycling in the medullary osmotic gradient?
Contributes ~50 % of medullary tonicity—ADH-dependent.
160
How does the vasa recta contribute to the preservation of the medullary osmotic gradient?
Counter-current exchange minimizes washout (slow
161
What is Bartter Syndrome?
A genetic disorder characterized by a group of disorders affecting kidney function
162
What mutations are associated with Bartter Syndrome?
Mutations in NKCC2
163
What are the clinical features of Bartter Syndrome?
Polyhydramnios
164
What laboratory findings are typical in Bartter Syndrome?
↑ renin/aldosterone
165
What histological change is observed in Bartter Syndrome?
Hyperplasia of juxtaglomerular cells
166
What is the treatment for Bartter Syndrome?
Fluid/electrolyte replacement
167
What is the prognosis for Bartter Syndrome?
Variable; neonatal forms severe
168
Fill in the blank: Bartter Syndrome is caused by mutations in NKCC2
ROMK
169
True or False: Hypercalciuria is a feature of all types of Bartter Syndrome.
170
What are the characteristics of DCT cells?
Small diameter
171
What types of cells are found in the collecting duct?
Principal cells and intercalated cells
172
What is the function of type A intercalated cells?
Secrete H⁺
173
What is the function of type B intercalated cells?
Secrete HCO₃⁻
174
What are the characteristics of principal cells in the collecting duct?
Pale
175
What is the function of the Macula Densa?
Specialised DCT plaque sensing tubular NaCl via NKCC2; modulates renin and afferent tone
176
What receptor does ADH (Vasopressin) act on in principal cells?
V₂-receptor (Gs)
177
What is the effect of ADH on cAMP levels in principal cells?
↑cAMP
178
What is the role of PKA in the action of ADH?
Phosphorylation of AQP2
179
What happens to AQP2 as a result of ADH action?
Trafficking to apical membrane
180
In addition to AQP2
what does ADH stimulate in the inner-medullary collecting duct?
181
What is the effect of stimulating UT-A1/3 in the inner-medullary collecting duct?
Enhancing urea permeability and medullary gradient
182
Fill in the blank: ADH (Vasopressin) acts on the _______ receptor in principal cells.
V₂-receptor
183
True or False: ADH increases the permeability of the inner-medullary collecting duct to urea.
t
184
What effect does increased apical AQP2 have on water?
↑apical AQP2 leads to rapid equilibration with hyperosmotic interstitium and concentrated urine.
185
How does urea transport affect interstitial osmolality?
↑transport raises interstitial osmolality
186
Fill in the blank: Increased _______ leads to concentrated urine due to rapid equilibration with hyperosmotic interstitium.
apical AQP2
187
True or False: Increased urea transport decreases interstitial osmolality.
188
What triggers the release of renin?
Low renal perfusion
189
What is angiotensinogen converted into?
Angiotensin I
190
What enzyme converts Angiotensin I to Angiotensin II?
ACE (Angiotensin-Converting Enzyme)
191
What are the effects of Angiotensin II?
Systemic arteriolar vasoconstriction
192
Fill in the blank: Low renal perfusion
sympathetic β₁
193
What is the overall purpose of the RAAS system?
To restore arterial pressure
194
What effect does Ang II have on PCT Na⁺-H⁺ Antiporter?
Ang II up-regulates NHE3 activity via AT₁ receptor
195
What is the result of increased NHE3 activity due to Ang II?
↑Na⁺/HCO₃⁻ reabsorption
196
What physiological processes are influenced by Ang II’s action on the PCT?
Volume restoration
197
Fill in the blank: Ang II contributes to _______ and metabolic alkalosis in volume depletion.
volume restoration
198
True or False: Ang II decreases NHE3 activity in the PCT.
199
What receptor mediates the up-regulation of NHE3 activity by Ang II?
AT₁ receptor
200
What receptor does aldosterone bind to in principal cells?
Cytosolic mineralocorticoid receptor
201
What are the effects of aldosterone binding to its receptor?
Transcription of ENaC
202
What is the result of increased Na⁺ reabsorption due to aldosterone?
Expansion of ECF volume and raising BP
203
Fill in the blank: Aldosterone increases _______ reabsorption and _______ secretion.
Na⁺; K⁺/H⁺
204
True or False: Aldosterone has no effect on water retention.
205
What occurs during sympathetic activation in low ECF?
α₁ vasoconstriction (↓RBF
206
What is a consequence of chronic sympathetic tone in dysautonomia or heart failure?
Renal Na⁺ retention leading to oedema
207
What happens to Na⁺ balance in denervation due to transplant?
Loss of rapid reflexes but long-term Na⁺ balance preserved via humoral mechanisms
