Renal Physl 5 Flashcards

1
Q

What is the initial step in the formation of urine?

A

Filtration

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2
Q

What percent of plasma is filtered out of glomerular capillaries at anytime?

A

20%. The rest returns into systemic circulation

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3
Q

What is the Filtration Fraction?

A

The proportion of plasma volume that filters into the tubule

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4
Q

What are the three filtration barriers in the renal corpuscle?

A
  • Glomerular capillary endothelium
  • Basal Lamina (basement membrane)
  • Epithelium of bowman’s capsule
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5
Q

What does it mean that Glomerular capillaries are fenestrated?

A

They have large gaps between endothelial cells

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6
Q

What do the large gaps between the glomerular capillary endothelial cells do?

A

They help to facilitate filtration by allowing solutes to pass through but not plasma proteins or blood cells

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7
Q

What helps to repel plasma proteins in the glomerular endothelium?

A

The surface being comprised of negatively charged proteins that repel plasma proteins

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8
Q

What is the Glomerular Basement Membrane (basal lamina)?

A

A layer of extracellular matrix that is acellular

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9
Q

What does the GBM (basal lamina) separate?

A

It layer separates the glomerular capillary endothelium from the epithelium of the bowman’s capsule

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10
Q

What is the GBM (basal lamina) composed of?

A

Negatively charged glycoproteins and collagen

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11
Q

What epithelium is closest to the glomerular capillaries?

A

The bowman’s capsule epithelium

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12
Q

What is the Bowman’s capsule epithelium composed of?

A

Podocytes

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13
Q

Why are they called Podocytes?

A

Because they feature long foot like processes

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14
Q

What can pass through the slits of podocytes?

A

Filtrate can pass through

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15
Q

What cells are in between and around glomerular capillaries?

A

Mesangial cells

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16
Q

What can Mesangial cells do and why?

A

They are capable of contracting which can alter capillary blood flow and the amount of filtrate entering the tubule

17
Q

What forces are found in the glomerular capillaries?

A
  • Capillary hydrostatic pressure
  • Capillary colloid osmotic pressure
  • Bowman’s capsule hydrostatic pressure
18
Q

What kind of pressure does blood in glomerular capillaries exert?

A

Glomerular capillary hydrostatic pressure

19
Q

What is Glomerular capillary hydrostatic pressure?

A

The pressure the blood in the glomerular capillaries exerts on the capillary wall

20
Q

What does Glomerular Capillary Hydrostatic Pressure Favor?

A

Fluid filtration out of the capillary and into bowman’s capsule

21
Q

Why does Glomerular capillary hydrostatic pressure favor filtration?

A

Because Bowman’s capsule hydrostatic pressure is normally lower

22
Q

What opposes filtration?

A

Protein remaining the capillaries

23
Q

What pressures oppose filtration?

A
  • Bowman’s capsule hydrostatic pressure

* Capillary colloid osmotic pressure

24
Q

What is the Glomerular filtration rate?

A

The volume of fluid entering Bowman’s capsule/unit time

25
What two things is GFR influenced by?
* Net filtration pressure | * Filtration Coefficient (Kf)
26
What is net filtration pressure based on the balance of?
The three forces
27
What can net filtration pressure be altered by?
Renal blood flow and blood pressure
28
What can raise glomerular hydrostatic pressure and drive further filtration and increasing GFR?
Increasing renal blood flow and blood pressure
29
What are the two main components of the filtration coefficient?
* Total surface area for filtration | * Permeability of barrier between capillaries & Bowman's capsule
30
What happens if functional nephrons and glomerular capillaries are lost?
The filtration coefficient and GFR are reduced