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FHB > RENAL 03 - Filtration and blood flow > Flashcards

RENAL 03 - Filtration and blood flow Flashcards

1
Q

What is the glomerular filtration barrier composed of (3)

A

Fenestrated capillary epithelium
fused basement membrane with negative charge barrier
podocyte foot processes (slit diaphragm)

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2
Q

Kidneys are activated by what branch of ANS, (and what branch does not affect kidneys)

A

SNS (PSNS does not affect them)

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3
Q

Majority of SNS innervation is on which arterioles set?

A

Afferent

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4
Q

Purpose of fenestrated epithelium

A

allow substances to pass through endothelial cells

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5
Q

purpose of basement membrane

A

negative charge helps with selectivity of what can go through -repels proteins

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6
Q

purpose of podocyte foot processes / slit diaphragm

A

processes can expand and contract out, helps by acting as filtration barrier against macromolecules

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7
Q

Why doesn’t albumin get into the tubular system?

A

it’s small, so it gets through the fenestrate, but it is repelled by the basement membrane’s negative charge

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8
Q

How does molecular weight impact filtration

A

the larger the molecule it is filtered less

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9
Q

how does electrical charge impact filtration

A

negatively charged molecules are filtered less, but positively charged molecules are filtered more (and even more filtered than neutral molecules)

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10
Q

Properties of inulin and filtration

A

although inulin is very complex, its overall molecular weight is low, so it is freely filtered, and it lacks a charge that is repelled by basement membrane so it gets through.

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11
Q

How much of the RPF passes through into the bowman’s space?

A

20%

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12
Q

Does glucose go through the glomerular filtration barrier?

A

Yes

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13
Q

Do large proteins go through glomerular filtration barrier?

A

No

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14
Q

What are direct determinants of glomerular filtration rate?

A

Starling forces (permeability, hydrostatic pressure, oncotic pressure, put together being the Net Filtration Pressure)

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15
Q

Compared to skeletal capillaries, the Kf of glomerular capillaries is (higher or lower)

A

higher because of the fenestrations (windows)

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16
Q

Blood flow to kidneys can be determined by what equation?

A

Q=deltaP/R

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17
Q

Kidneys have a vascular system in ___(series/parallel)__. What does this mean about the overall resistance?

A

Parallel; this means total resistance is quite low

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18
Q

Mean pressure in glomerular capillaries is ____(high/low)___ compared to skeletal capillaries?

A

High

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19
Q

What happens to oncotic pressure along the length of the glomerular capillary? Why?

A

It becomes higher. This is because you’re filtering out the fluid, so you’re concentrating the protein there (more protein per unit volume)

20
Q

Hydrostatic pressure in glomerulus vs skeletal muscle interstitium?

A

It’s higher, but still much lower than the hydrostatic pressure in the glomerular capillary

21
Q

Hydrostatic pressure in the glomerular capillary?

A

High throughout the length of the capillary and much higher than what you would find in skeletal muscle capillaries due to the fact that it is between two arterioles

22
Q

Oncotic pressure in bowman’s space

A

near zero

23
Q

Aside from just “fenestrations” what can be attributed to high amount of filtration going on in the glomerulus?

A

high surface area of openings in capillaries overall leading to a high amount of fluid coming out

24
Q

What would the effect of renal arterial pressure increasing be on GFR?

A

This would increase GFR due to an increase in hydrostatic pressure

25
Q

What would the effect of relaxation of glomerular mesangial cells be on the GFR?

A

This would increase glomerular surface area (increase in permeability) and as a result you increase filtration (increase in GFR)

26
Q

What would the result of an intratubular pressure increase (ex. obstruction of a tubule, extrarenal urinary system obstruction) be on GFR?

A

This will DECREASE the GFR. This is because you would be increasing the hydrostatic pressure in the bowman’s space, which would oppose filtration

27
Q

What would the effect of an increase in systemic oncotic pressure be on the GFR?

A

This will decrease filtration rate (decrease GFR)

28
Q

What would a decreased RBF do to the GFR?

A

This will decrease GFR, partly due to an increase in the oncotic pressure along the glomerular capillaries (it becomes concentrated)

29
Q

What would the effect of afferent arteriole dilation be on GFR?

A

This will increase GFR ; this is decreasing afferent arteriolar resistance and increasing flow to the area, therefore, the pressure is increasing.

30
Q

What would the effect of constricting the efferent arteriole be on GFR?

A

This will increase GFR because you’re increasing resistance to flow on the exit side

31
Q

If you have a decrease in effective circulating volume, what is the effect on GFR? What is a situation in which this might happen?

A

This would result in a decrease in GFR. This would happen in, for instance, heart failure or hemorrhage.

32
Q

If you hve an immune complex on the glomerulus, what is the result of GFR?

A

This is going to lead to inflammation of the glomerulus which decreases overall glomerular filtration rate; however you also get holes in the capillaries so what DOES get through can be quite large and include RBC’s, WBC’s, and proteins

33
Q

What is the result of kidney stones on glomerular filtration rate?

A

This would lead to a backup of pressure that eventually increases bowman’s space hydrostatic pressure and decreases the overall glomerular filtration rate

34
Q

how do we calculate blood flow

A

Flow is equal to the pressure gradient of two locations over the resistance of the system

35
Q

Where does the majority of blood flow go in the kidney

A

Cortex

36
Q

Where is the vast MINORITY of vascularization in the kidney

A

inner medulla ; you really only have vasa recta here along the juxtamedullary nephrons

37
Q

Where is the largest pressure drop in the kidney vascular pressure?

A

Think about the highest resistance vessels (just like what Jonathan taught us, it’s the arterioles, both afferent and efferent)

38
Q

Where is oncotic pressure highest in the kidneys

A

Efferent arterioles (we concentrated protein in the glomerular capillaries and in the peritubular capillaries we’re going to dilute it back down when we save water)

39
Q

Constriction of afferent arteriole leads to what affect of renal blood flow and what affect on GFR

A

Decrease RBF, decrease GFR (due to decrease in hydrostatic pressure in glomerular capillaries)

40
Q

Constrition of EFFERENT arteriole leads to what affect on renal blood flow and what affect on GFR

A

This leads to a DECREASE in renal blood flow (resistance increases in the exit portion) but an INCREASE in GFR due to an increase in hydrostatic pressure along the glomerular capillary

41
Q

Dilation of the efferent arteriole leads to what affect on renal blood flow and GFR

A

This will increase RBF and decrease GFR due to a decrease in hydrostatic pressure within the glomerular capillaries

42
Q

What is the effect of dilation of the afferent arteriole on renal blood flow and GFR?

A

This is going to lead to an increase in renal blood flow and in increase in GFR due to an increase in glomerular capillary hydrostatic pressure

43
Q

GFR and RBF can be maintained over….. what range of pressures?

A

A broad range of pressures (100-180mmHg)

Therefore if you increase arterial blood pressure, you don’t necessarily increase RBF and GFR

44
Q

At what arterial blood pressure do kidneys begin to shut down?

A

70mmHg

45
Q

Intrinsic regulation of GFR and RBF

A

vasoconstricting and vasodilating factors, myogenic response, tubuloglomerular feedback from vasa recta

46
Q

Extrinsic regulation of GFR and RBF

A

Sympathetic nervous system, bloodborne or endogenous sybstances (ex. angiotensin II), stress factors such as hemorrhage

FHB (54 decks)

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