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Physiology Block 7 > Filtration And Renal Blood Flow > Flashcards

Filtration And Renal Blood Flow Flashcards

1
Q

Where does filtration occur

A

Glomerulus only

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2
Q

What is the glomerulus

A
  • Capillary bed with two arterioles
  • afferent brings blood, efferent removes blood
  • efferent supply peritubualr capillary with renal blood flow (RBF)
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3
Q

What is at the beginning of the PCT where filtrate enters after the glomerulus

A

Bowmans capsule

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4
Q

What forms the filtration membrane

A

Capillary endothelial cells, basement membrane and podocytes

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5
Q

How is rate of filtration measured

A

By glomerular rate

-GFR-clearance of inulin or creatinine

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6
Q

What is the best watt to determine GFR

A

By clearance of a molecule that is only filtered such a inulin or creatinine

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7
Q

What’s the quickest way to measure GFR

A

Blood creatinine levels.

-it takes a big change in GFR to change the creatinine levels in blood

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8
Q

Decreased GFR does what to creatinine

A

Increases

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9
Q

What gets filtered

A
  • water, small solutes
  • in proportion to their free plasma concentration
  • tubular fluid is same as plasma
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10
Q

What doesn’t filter

A
  • plasma proteins (mostly)

- small solutes bound to plasma proteins

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11
Q

Amount of solute that enters the tubular fluid

A

Filtered load

GFR*[Xa]
Usually reported as mg/min

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12
Q

What do we use filtered load to determine

A

How a solute is handled in the nephron because filtration and secretion adds solutes to the tubular fluid while secretion removes them we can say that

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13
Q

Filtered load + secretion =

A

Excretion

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14
Q

If secretion > filtered load then

A

(Net) secretion had to occur

-reabsorption COULD have occurred, just more secretion

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15
Q

If excretion < filtered load then

A

Net reabsorption had to occur

-secretion could have occurred, just more reabsorption

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16
Q

If excretion = filtered load

A

Then there was no net transport

Reabsorption and secretion could have occurred, just balanced

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17
Q

What are the forces that effect filtration

A

The same things that regulate filtration in other cap beds (pressure and osmolarity pressure)

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18
Q

Pressure in glomerulus

A

High because of two arterioles

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19
Q

Where is there low hydrostatic tissue pressure

A

Bowmans space, usually no osmotic pressure here

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20
Q

Why is filtration heavily favored

A

Because of P(GC)

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21
Q

Why can we easily alter P(GC)

A

Because there are two arterioles

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22
Q

What is the primary way of controlling GFR and RBF?

A

Altering P(GC) with the two arterioles

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23
Q

Kf in kidneys

A

Huge

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24
Q

Effect on GFR if you increase P(GC)

A

Hypertension (increased GFR)

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25
Effect on GFR if you decreases P(GC)
Decrease (hypotension)
26
Effect on GFR if you increase osmotic (GC)
Decrease (dehydration)
27
Effect on GFR if you decrease osmotic GC
Increase (liver failure)
28
Effect on GFR if you increase P(BS)
Decrease (ureter blockage)
29
Effect on GFR if you decrease P(BS)
Increase (hard to do this, its already low)
30
Effect on GFR if you increase osmotic (BS)
Increase (damage filtration membrane)
31
Effect on GFR if you decrease osmotic (BS)
Decrease (hard to do, its already low)
32
Effect on GFR if you increase KF
Increase (damage filtration membrane)
33
Effect on GFR if you decrease KF
Decrease (fibrosis)
34
How many arterioles does the glomerulus have
2
35
What does changing either of the arterioles do
Affects GFR and renal blood flow
36
Small changes in P(GC) result in what
LARGE changes in GFR, bc Kf is so large
37
Changes in afferent diamter alter GFR and RBF how
In the same way. - constrict afferent-reduce both - dilate afferent-increase both
38
Changes in efferent affect GFR and RBF how
In opposite ways - constrict-increase PGC and GFR but reduce RBF - dilate efferent-reduce PGC and GFR but increase RBF
39
Dilating the afferent arteriole would have what affect on GFR and RBF
Increase both
40
If a patients filtered load of K+ is 10mg/min and excretion rate is 1mg/min, how is K handled in the nephron
It is filtered, reabsorped, secreted,
41
What is renal blood flow calculated by
PAH clearance
42
Blood supply of the nephrons
Each nephron has its own blood supply, and is VERY close to a peritubular capillary to allow for transport
43
What does the closeness of the nephron to the peritubular capillary ensure
Proper movement of solutes into and out of urine. Tight regulation is required
44
What kind of flow does the vasa recta need to have
Low
45
What kind of blood flow does kidneys have
High
46
Kidney and control of blood flow
The kidney is able to control its own blood flow in response to change in pressure
47
What kind of mechanism does the kidney use to regulate its own blood flow
Autoregulation
48
How constant is the renal blood flow
Flow remains constant over 100mmHg + change in pressure
49
What does increase in MAP do to GFR, renal blood flow, and urine output
Renal blood flow and GFR may be relatively constant, but as pressure increases there is an increase in urine flow
50
What are the mechanisms of autoregulation that the kidney uses
- myogenic response - tubuglomelur feedback - RAAS system
51
Myogenic response of the kidney to regulate blood flow
- response of smooth muscle to stretch - stretch a smooth muscle and it will actively contract against that force - maintains constant flow by changing resistance
52
How does the myogenic response in the kidneys maintain constant flow
By changing resistance
53
If you increase the transmural presure in a vessel, what happens
The diameter of the vessel gets smaller
54
How does the tubuglomerular feedback work for regulation of renal blood flow
Nephron is able to sense GFR and regulate RBF to maintain it by alteration in diameter of afferent and/or efferent arterioles
55
In the tubuglomerular feedback, what is linked with GFR and blood pressure?
Tubular sodium concentration | -high GFR=high tubular Na+
56
Where does the tubuglomerular feedback occur
At the juxtaglomerular apparatus (JGA) - macula densa - juxtaglomerular cells
57
In the tubuglomerular feedback, what happens if GFR is high
More NaCl will be filtered and will be taken up by macula densa
58
What does more sodium in the tubular fluid do
Increases the activity of Na/K ATPase, which means more production of adenosine (Na levels low inside of cells because of the ATPase)
59
What does build of adenosine do
Binds to smooth muscle cells and causes constriction of AFFERENT arterioles, reducing GFR and RBF Also lowers renin production, so you get less AngII, which lowers pressure and GFR
60
What happens if there is not enough NaCl
Dilates afferent and increases renin secretion
61
All the things about increased GFR
- increases Na flow - increased macula densa Na+ transport - increased adenosine release from macula densa - adenosine binds to A1 receptor - A1 receptor opens Ca channels in afferent - afferent constricts - P(GC) goes down - GFR goes back down towards normal
62
All the things about not enough GFR
- decrease flow of Na - decrease macula densa Na+ transport - decrease adenosine released from macula densa - less adenosine binds to A1 receptors - fewer A1 receptors opened Ca2+ channels in afferent arterioles - afferent dilates - P(GC) increases - GFR increases
63
When is renin released from JGA
- arterial pressure is low - tubular sodium decreases - effective circulating volume (ECV) decreases
64
What is EVC (effective circulating volume)
How well tissues are being perfumed
65
Does the GFR need to be high or low for renin to be released
Low
66
What does release of renin eventually do
Increases AngII and aldosterone levels
67
What do low levels of AngII do
Preferentially constricts efferent arterioles and increases GFR
68
What do high levels of AngII do
Constrict afferent AND efferents. This can be damaging
69
What does aldosterone do
Increases Na and water retention, which increases blood volume
70
In which arterioles would the myogenic response autoregulatory response be most prominent
Afferent
71
Myogenic and macula densa work mostly on the _____ arterioles
Afferent
72
ANgII acts preferentially on _______ arterioles
Efferent
73
Effect of afferent and efferent constriction and dilation on RBF and GFR
They have the same effect on RBF and opposite effects on GFR
74
What is the kidney richly innervated by
SNS
75
When does the SNS constrict the afferent AND efferent arterioles?
Only in times of high SNS stimulation (massive hemorrhage)
76
What does norepinephrine and epinephrine do to kidney
Only used in extreme situations, will shut kidney down to preserve the heart and brain
77
Nitric oxide action on the arterioles
Vasodilators, counteracts AngII's effect on the AFFERENT
78
Prostaglandins effects on arterioles of kidneys
Vasodilators, counteract AngIIs effect on AFFERENTS
79
What are prostaglandins upregulated by
AngII and NE production to maintain GFR and RBF
80
NSAIDS and prostaglandin in the kidneys
NSAIDS 9any COX inhibitors) will block production, could lead to kidney ischemia in already hypotensive patients
81
Why should you not give someone NSAIDS if they are hypotensive
NSAIDS will block production of prostaglandins, could lead to kidney ischemia
82
Kidney response to hemorrhage
- decrease MAP, CO, preload, RBF, GFR - cant get a lot of blood to kidney, decreased Na+ - myogenic response dilates afferent - JGA decreases adenosine, dilates afferent, decreases Ang, increases renin - increased renin causes constriction, AngII, increased TPR, constricted efferent, and increased MAP
83
Kidneys response to massive MI
Decreased CO, MAP, profusion, RBF, GFR | Sets off chain, look it up
84
Response to high dose of ACE-I
Less ANgII, decreases constriction of efferent, decrease TPR
85
Low ECF
Increase in total blood volume

Physiology Block 7 (10 decks)

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