Renal Flashcards
(107 cards)
1
Q
Which embryological layer are the kidneys derived from?
A
Mesoderm
2
Q
At what vertebral level do the kidneys lie?
A
T12-L3
3
Q
Right kidney is lower than the left kidney because…
A
It’s pushed down by the liver
4
Q
At what vertebral level is the hilum of the right kidney?
A
L2
5
Q
At what vertebral level is the hilum of the left kidney?
A
L1
6
Q
How many layers does the kidney have?
A
3: the cortex, medulla and the renal pelvis
7
Q
What does the cortex contain? (4)
A
Renal corpuscle (glomerulus and Bowman’s capsule)
PCT
DCT
Medullary ray (LoH and CD) –> gives the cortex its striated appearance
8
Q
What does the medulla contain? (4 tubular structures)
A
CD
Thin descending limb of LoH
Thin and thick ascending limb of LoH
Blood vessels
9
Q
What type of epithelium lines the renal pelvis?
A
Transitional epithelium/ urothelium
10
Q
What is the renal pelvis continuous with proximally and distally?
A
Continuous proximally with the CDs
Continuous distally with the ureters
11
Q
Describe the blood supply of the kidneys
A
Renal arteries Segmental arteries Interlobar arteries Arcuate arteries Interlobular arteries Afferent arteriole Glomerular capillaries Efferent arteriole Peritubular capillaries (+ vasa recta) Interlobular veins Arcuate veins Interlobar veins Segmental veins Renal veins
12
Q
Are the kidneys extraperitoneal or retorperitoneal?
A
Retroperitoneal
13
Q
What % of cardiac output do the kidneys receive?
A
20%
14
Q
Total renal blood flow?
A
1L/min
15
Q
Total urine flow?
A
1ml/min
16
Q
What is the maximum filtration rate of the kidneys?
A
125ml/min
17
Q
What does the renal corpuscle contain?
A
Glomerular tuft and Bowman’s capsule
18
Q
What is the glomerular tuft?
A
Network of glomerular capillaries (w/ fenestrated walls) supported by mesangial cells
19
Q
What do the mesangial cells do? (3)
A
- Produce extracellular matrix protein (structural support)
- Phagocytose glomerular unit breakdown products
- Contract to tighten capillaries + reduce GFR
20
Q
What are the 3 layers of the filtration barrier?
A
- Glomerular capillary endothelium
- Basement membrane
- Foot processes of the podocytes (epithelial cells)
21
Q
What 2 components make the juxtaglomerular apparatus (JGA)?
A
Afferent arteriole
DCT
22
Q
Location and function of GRANULAR CELLS.
A
Found in endothelium of afferent arteriole (in JGA).
Detect low bp and secrete renin in response.
23
Q
Location and function of MACULA DENSA CELLS.
A
DCT contributes to it (in JGA).
Detect Na+ and regulates tubuloglomerular feedback (sends signals to granular cells to secrete renin).
24
Q
In tubuloglomerular feedback, what happens when filtration is slow?
(check answer)
A
Filtration is slow –> More Na+ is absorbed –> Macula Densa send a signal to REDUCE afferent arteriole resistance –> this increases glomerular filtration
25
Cells in the PCT contain what and why? (3)
Microvilli on apical surface --> increase SA for reabsorption
Lots of mitochondria --> active transport of substances
Lysosomes (histology: black dots) --> break down proteins accidentally reabsorbed from urinary space
26
What moves out of the thin descending limb of the LoH?
Water (passively) flows out, concentrating the urine
27
What moves out of the ascending limb of the LoH?
Desired ions are actively pumped out and into the interstitium
28
How does the DCT regulate acid-base balance?
Secreting H+
Absorbing HCO3-
(via intracellular carbonic anhydrase)
29
How does DCT regulate Na+ and K+ concentration?
Exchanging urinary Na+ (reabsorption) for body K+ (excretion)
30
What hormone mediates Na+ reabsorption in the DCT?
Aldosterone
31
How is urine propelled down the ureters?
Peristalsis (contain two muscular layers: circular and longitudinal)
32
Which structures contain transitional epithelium?
```
Renal Pelvis
Ureter
Bladder
In females: proximal urethra
In males: membranous urethra
```
33
How long is the urethra in females?
4-5cm
34
How long is the urethra in males?
20cm
35
Describe the urethra in males? (3)
Prostatic urethra
Membranous urethra
Penile urethra
36
What 2 cell types make up the collecting duct?
Principal cells
| Intercalated cells
37
What do PRINCIPAL CELL in the CD do?
Respond to aldosterone (Na+/ K+ exchange)
| Respond to ADH: insert aquaporin channels into apical membrane to increase H20 reabsorption
38
What do INTERCALATED CELLS in the CD do?
Acid-base balance:
ALPHA - secrete ACID
BETA - secrete BICARBONATE
39
Name the determinants of what crosses the filtration barrier. (5)
1. Pressure
2. Size of moleucle
3. Charge of molecule
4. Rate of blood flow
5. Binding to plasma proteins
40
What is the glomerular filtration rate (GFR)?
Volume of fluid filtered from the glomeruli into the Bowman's space per unit time (min)
41
GFR (physiology)=
= Kf (PGC - PBS - pie.GC)
42
What is the only protein that should be found in urine?
Tamm Horsfall protein (produced by LoH)
43
What does constricting the afferent arteriole do to GFR?
Reduces PGC, reduces GFR.
44
What does constricting the efferent arteriole do to GFR?
Increases PGC, increases GFR
45
What does dilating the afferent arteriole do to GFR?
Increases PGC, increases GFR
46
What does dilating the efferent arteriole do to GFR?
Reduces PGC, reduces GFR
47
Formula for measurement of GFR (using substance M).
Pm x GFR = Um x urine flow rate
48
Filtration fraction=
GFR / renal plasma flow
49
Avg urine output?
0.5ml/kg/hr
50
Define renal clearance.
The volume of plasma from which a substance is completely removed by the kidney per unit time
51
If the renal clearance of substance M is 125ml/min, what does this mean?
After being freely filtered from glomerulus, substance M is neither reabsorbed or secreted.
52
Clearance=
(urine conc x urine vol)/ plasma conc
53
Describe the process of bulk reabsorption in the PCT (4)
1. Basolateral Na-K ATPase maintains the Na+ concentration gradient from the lumen into the PT cell
2. Na+ reabsorption drives the reabsorption of co-transported substances and the secretion of H+
3. Water follows passively by osmosis
4. Bicarbonate reabsorption (using H+ and carbonic anhydrase)
54
Describe the countercurrent multiplier system (LoH) (3)
1. Ascending limb pumps out NaCl into interstitium
2. Medullary hypertonicity increases
3. Water diffuses out of descending limb into interstitium
55
How is urea involved in the countercurrent medullary interstitium?
Urea is an osmotically active molecule ==> increases medullary interstitial osmolarity
56
Why doesn't blood flow wash out the osmotic gradient? (4)
- Vasa recta
- Long capillaries extend deep into the medulla
- Permeable to solute + H2O
- Solute + H2O carried away by bulk flow
57
Why is the amount of blood flow leaving the vasa recta 2x higher than the amount of blood entering it?
Because of the NaCl + H2O reabsorbed from the LoH and CD
58
What takes place in the DCT? (3)
Fine regulation of Na, K, Ca and Pi
Separation of salt (Na) from H2O
Dilution of urine
59
What takes place in the CD? (3)
Acid secretion (intercalated cells)
Regulated H2O reabsorption (principal cells)
Regulated Na absorption and K secretion (principal cells)
60
What does aldosterone drive in the CD?
Na+ reabsorption and K+ excretion
61
How much fluid is present in a 70kg man?
40L
62
How much of total body fluid is intracellular?
26L
63
How much of total body fluid is extracellular?
14L
64
How much of the extracellular fluid is plasma?
3L
65
What's the range for normal plasma osmolality?
285-295mOsm
66
Plasma osmolality=
2(Na + K) + glucose + urea
67
How does the ingestion of excess water lead to the reduced release of vasopressin? (6)
```
Increased H2O ingested
Decreased body fluid osmolarity
Decreased firing of hypothalamic osmoreceptors
Decreased vasopressin secretion
Decreased tubular permeability to H2O
More water is excreted
```
68
How does loss of extracellular water lead to the increased release of vasopressin? (6)
```
Water loss (diarrhoea/ haemorrhage)
Decreased cardiovascular pressure
Reduced firing by cardiovascular baroreceptors
Increased vasopressin release
Increased tubular permeability to H2O
Less water is excreted
```
69
Na+ excreted=
Na+ filtered - Na+ reabsorbed
70
How is GFR altered when total body Na+/ plasma volume decreases? (3 steps)
Reflex vasoconstriction of afferent arteriole
Decreases GFR
Increases Na + H2O reabsorption
71
How is GFR altered when total body Na+/ plasma volume increases? (3 steps)
Reflex vasodilation of afferent arteriole
Increases GFR
Decreases Na + H2O reabsorption
72
How is renin secretion initiated? (3)
- Macula densa cells detect less NaCl
- Sympathetic stimulation
- Reduced arteriolar stretch
73
What does renin do?
Cleaves angiotensinogen into angiotensin 1
| Increases BP
74
What converts angiotensin 1 into angiotensin 2?
ACE
75
What does angiotensin 2 do? (4)
- Stimulates release of ALDOSTERONE
- Vasoconstricts efferent arteriole
- Increases Na+ reabsorption in PCT
- Increases VASOPRESSIN release
All act to raise blood volume and thus pressure
76
What does aldosterone do? (2)
Stimulates transcription of ENaC (on principal cells in CD) --> increases Na+ and H2O reabsorption.
Also, causes more K+ to leak out
77
What does ANP (atrial natriuretic peptide) do? (3)
- Blocks ENaC channels --> inhibits Na+ and H2O reabsorption
- Directly inhibits aldosterone secretion
- Vasodilates afferent arteriole --> increases GFR --> increases Na+ excretion
78
What 2 main transporter channels does the PCT contain?
Na+ cotransporter channels (reabsorption of organic substances)
Na+/H+ countertransporter channels (bicarbonate reabsorption)
79
What main transporter channel does the ascending limb of LoH contain?
NKCC2 (reabsorbs Na+, K+ and 2Cl-)
80
What 2 main transporter channels does the DCT contain?
Na+/Cl- cotransporter
| Ca2+ channel
81
What main transporter channels does the CD contain?
Apical side: ENaC, K+ channels and aquaporins
| Basolateral side: V2R
82
Describe the relationship between osmoreceptors and vasopressin release.
Osmoreceptors act as the ACCELERATOR for vasopressin release.
83
Describe the relationship between baroreceptors and vasopressin release.
Baroreceptors act as the BREAK for vasopressin release.
84
What does parathyroid hormone do in the kidneys? (2)
- Increases Ca2+ reabsorption
| - Converts Vit D to its active form
85
pH=
-log10[H+]
86
Normal pH range of the blood?
7.35 -7.45
87
Define a BASE
Proton acceptor
88
Define an ACID
Proton donor
89
Define base excess
Quantity of acid required to return plasma pH to normal
90
Define standard base excess
Quantity of acid required to return ECF back to normal pH
91
Define acidosis
Disorder causing blood to be more acidic than normal
92
Define alkalosis
Disorder causing blood to be more alkaline than normal
93
Define acidemia
Low blood pH
94
Define alkalemia
High blood pH
95
Anion gap=
[Na+] + [K+] -[Cl-] - [HCO3-]
96
What is the average anion gap value?
10-16
97
What does a wide anion gap suggest?
Increased acid in the body eg ingestion of acid, ketoacidosis, lactic acidosis
98
What does a narrow anion gap suggest?
High Cl- so increased GI HCO3- loss, renal tubular acidosis
99
What are the two main urinary buffers?
Phosphate buffer
| Ammonium buffer
100
Signs of respiratory acidosis
Decreased pH
Increased pCO2
Increased HCO3-
101
Signs of respiratory alkalosis
Increased pH
Decreased pCO2
Decreased HCO3-
102
Signs of metabolic acidosis
Decreased pH
Decreased HCO3-
Decreased pCO2
103
Signs of metabolic alkalosis
Increased pH
Increased HCO3-
Increased pCO2
104
Compensatory mechanism for resp acidosis
Increased renal HCO3- retention
| Increased renal H+ secretion
105
Compensatory mechanism for resp alkalosis
Decreased renal H+ secretion
| Increased HCO3- secretion
106
Compensatory mechanism for metabolic acidosis
Hyperventilation
107
Compensatory mechanism for metabolic alkalosis
Hypoventilation
