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Semester 3 > Urinary Session 3 > Flashcards

Urinary Session 3 Flashcards

1
Q

What do the efferent arterioles in cortical nephrons drain into?

A

Peritubular capillaries

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2
Q

How does the diameter of the efferent and afferent arterioles compare in cortical nephrons?

A

Afferent>efferent

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3
Q

What does the efferent arteriole of juxtamedullary nephrons drain into?

A

Vasa recta

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4
Q

How does the sympathetic supply of cortical and juxtamedullary nephrons compare?

A

Cortical have rich supply, juxtamedullary have poor supply

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5
Q

How does the renin concentration in cortical and juxtamedullary nephrons compare?

A

High in cortical, almost none in juxtamedullary

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6
Q

Where are cortical nephrons located?

A

Outer cortex

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7
Q

Where are juxtamedullary nephrons found?

A

Inner part of cortex

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8
Q

How does the size of the glomerulus compare in cortical and juxtamedullary nephrons?

A

Smaller in cortical

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9
Q

What proportion of blood flow is filtered at any one time?

A

20%

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10
Q

Does the proportion of blood filtered depend on the nephron?

A

No

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11
Q

What is the ratio of cortical to juxtamedullary nephrons in the kidney?

A

90% cortical

10% medullary

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12
Q

What does the permeable capillary endothelium allow between cells?

A

Water
Salts
Glucose

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13
Q

What repels protein movement in the basement membrane?

A

-ve charge acellular gelatinous collagen/glycoprotein basement membrane

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14
Q

What determines the size of particles that can move through the filtration barrier?

A

Interdigitation of pseudopodia of podocytes

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15
Q

What is the largest molecule that can pass through the filtration barrier?

A

Inulin

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16
Q

Why do some smaller proteins not pass through the filtration barrier?

A

They have a negative charge

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17
Q

What causes proteinuria?

A

Loss of -ve charge on the basement membrane so proteins are more readily filtered

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18
Q

What are the three forces in plasma filtration?

A

Hydrostatic pressure in the capillary
Hydrostatic pressure in the Bowman’s capsule
Oncotic pressure difference between capillary and tubular lumen

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19
Q

What allows GFR to remain constant during small fluctuations in BP?

A

Autoregulation of hydrostatic pressure in the capillary

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20
Q

What is the myogenic response to small increases in BP?

A

Increased BP –> stretch afferent arteriole smooth muscle –> smooth muscle contacts to decrease blood flow

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21
Q

What is the myogenic response to small decreases in blood pressure?

A

No smooth muscle stretch –> afferent arteriole dilation

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22
Q

What is the response via tubular-glomerular feedback to a small increase in BP?

A

Increased BP –> increased GFR –> increased tubular flow rate –> increased sodium and chloride concentrations detected by macula densa cells –> adenosine release

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23
Q

What is the tubular-glomerular feedback response to a small decrease in BP?

A

Decreased sodium and chloride concentrations detected by macula densa cells –> prostaglandin release

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24
Q

When do the myogenic and tubular-glomerular feedback responses maintain GFR?

A

When BP is within physiological limits

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25
How do macula densa cells sense luminal sodium and chloride concentration?
Using concentration dependent uptake through NaK2Clco transporters in the apical membrane
26
What do macula densa cells stimulate the release of to control afferent arteriole vasomotor tone?
Adenosine or prostaglandins
27
What are the two types of nephrons found in the kidneys?
Cortical | Juxtamedullary
28
Why is movement of solutes and water in the nephron classed as reabsorption?
Substances have a already been absorbed into the blood once (especially in the intestines)
29
Why does bulk transport/isosmotic occur in the PCT?
Polarised tubule cells drive sodium uptake and other ions follow to maintain electro-neutrality
30
How can reabsorption occur?
Transcellular | Paracellular
31
Which type of reabsorption is predominantly used?
Transcellular
32
Which sodium transporters in the apical membrane of PCT cells are targeted by diuretics?
Na-H antiporter | Na-glucose symporter
33
Which sodium transporter in the apical membrane of Loop of Henle epithelial cells is targeted by diuretics?
Na-K-2Cl symporter
34
Which sodium transporter in the apical membrane of early distal tubule epithelial cells is targeted by diuretics?
NaCl symporter
35
Which sodium transporter in the apical membrane of late DCT and collecting duct epithelial cells is targeted by diuretics?
ENaC
36
What is the end result of reabsorption?
``` Reabsorption of: 100% filtered nutrients 80-90% filtered HCO3- 67% filtered Na+ 65% filtered water 65% filtered Cl- 65% filtered K+ ```
37
What provides a second route of entry for solutes that need to be secreted into the tubular fluid?
Secretion
38
What in the 80% of unfiltered plasma needs secretion into the tubule?
H+ K+ Organic anions
39
Describe the process of secretion into the tubular lumen.
3Na-2K-ATPase creates concentration and electrochemical gradient Entry of molecules by passive carrier-mediated diffusion down gradients Na-H antiporter creates H+ gradient H+-OC+ exchanger pumps in H+ to restore balance and in the process pumps OC+ into lumen
40
Why do cations compete to be transported?
Due to Tm limitation
41
How do cations enter and exit luminal cells?
Enter on basolateral side by one of several uniporters | Leave via H+ antiporter in apical membrane
42
Give some examples of endogenous cations.
``` ACh Dopamine Adrenaline Histamine Serotonin ```
43
Give some examples of drugs which are cations.
Sulfonamides Morphine Atropine Isoproterenol
44
Give some examples of endogenous anions.
Urate Bile salts Fatty acids
45
Give some examples of drugs that are anions.
Penicillin Salicylate NSAIDs
46
What must be considered when choosing a drug and calculating dosages?
That administered drugs will be secreted by the kidneys
47
What is the normal range of GFR for males?
115-125 ml per minute
48
What is the normal GFR range for females?
90-100 per minute
49
What is the benchmark measure of kidney health?
GFR
50
What characteristics does a substance used to measure GFR require?
Not altered in any way in the nephron Freely filtered Not secreted
51
Can a standalone GFR be used to assess kidney health?
No, needs a series of measurements to see where a pt's normal GFR is
52
What ultimately governs GFR?
Renal blood flow
53
What is the normal renal blood flow through the glomeruli?
~1.1 l per minute
54
What percentage of renal blood flow is haematocrit?
Usually 45%
55
What is normal renal plasma flow?
605 ml per min (0.55x1.1)
56
What is renal clearance?
Volume of plasma that is completely cleaned of a substance by the kidneys per unit time
57
How is renal clearance calculated?
(Concentration of substance in urine X urine volume)/concentration of it in plasma
58
What is renal clearance used to detect?
Glomerular damage Follow progress of diagnosed renal disease Determine GFR
59
What is the gold standard for measuring renal clearance?
Inulin
60
What substance is used clinically to measure renal clearance and why?
Creatinine as it doesn't have to be given IV like inulin
61
Why does using creatinine give a slight overestimate of renal clearance?
A small amount is secreted
62
What does eGFR account for?
Age affecting kidney function | Mass affecting creatinine levels
63
What is the Tm of glucose in males and females?
``` Males = 375 mg per minute Females = 300 mg per minute ```
64
What happens if plasma glucose concentration is 400 mg per ml in a male?
Filtered load is 4x125 = 500 mg per minute | As renal threshold is 375 mg per minute 125 mg per minute moves into the urine
65
What is normal plasma glucose concentration?
~1 mg per ml
66
Is normal plasma glucose concentration freely filtered in the Bowman's capsule?
Yes

Semester 3 (50 decks)

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