67: Renal Glomerular Filtration Flashcards

1
Q

The kidneys are partially protected by ….

A

Floating Ribs (False Ribs)

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2
Q

The cortex of the kidney contains:

A

-Convoluted tubules
– more active processes
– more blood flow (100x medulla)

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3
Q

The homeostatic functions of the kidney.

A

i. Filters and cleans the blood - eliminates waste products and water and urine production (1 – 1.5 L/day excreted) 
ii. Controls blood pH, electrolyte concentrations, and volume status

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4
Q

The endocrine functions of the kidney:

A

i. Synthesizes erythropoietin to stimulate blood cell production
ii. Converts 25-OH vitamin D into its active form 1,25-dihydroxycholecalciferol by the 1-a-hydroxylase enzyme in the proximal tubule
iii. Secretes renin enzyme into circulation to start the renin-angiotensinaldosterone (RAA) axis to increase blood pressure

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5
Q

What two components determine flux across the glomerulus?

A

Permeability and Glomerular filtration pressures

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6
Q

Filterability Coefficient (Kf) describes…

A

Permeability of the renal corpuscle

Normal range: 10-15 mmHg

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7
Q

Starling’s Law: 4 pressures in theory affect fluid movement

A
  1. Hydrostatic pressure of capillary (PG)
  2. Hydrostatic pressure of Bowman’s space (PBS)
  3. Oncotic pressure of blood (plasma) (piG) 4. (Oncotic pressure of Bowman’s space (piBS))
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8
Q

PGC decreases slightly from afferent to efferent due to ……. along the length of the capillary

A

Flow resistance

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9
Q

pGC increases from afferent to efferent due to ……..of fluid

A

Filtration

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10
Q

Rate at which the ultrafiltrate forms in Bowman’s space

A

Glomerular Filtration Rate (GFR)

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11
Q

Formula of Glomerular Filtration Rate (GFR)

A

GFR = Kf x ΔP Normal values of GFR = 90 - 140 ml/min

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12
Q

Effect of Constriction of Afferent Arterioles on (Renal plasma Flow) RPF and GFR:

A

Decreases RPF and GFR

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13
Q

Effect of Constriction of Efferent Arterioles on (Renal plasma Flow) RPF and GFR:

A

Decreases RPF

Increases GFR

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14
Q

Effect of Dilation of Afferent Arterioles on (Renal plasma Flow) RPF and GFR:

A

Increases RPF and GFR

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15
Q

Effect of Dilation of Efferent Arterioles on (Renal plasma Flow) RPF and GFR:

A

Increase RPF

Decrease GFR

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16
Q

How does Nephrotic Syndrome change Starling Forces?

A

Increased permeability of glomerular capillaries to plasma proteins
Results in Increased (piB)

17
Q

How does Urinary Tract Obstruction (Obstructive Uropathy)

change Starling Forces?

A

Backs up tubular flow

Results in Increased (PB)

18
Q

67% H20/solutes reabsorbed by proximal tubule – returned to bloodstream by ……….

A

Peritubular capillaries

19
Q

3 Starling forces that control H2O movement:

A
  1. Plasma oncotic pressure in peritubular capillary (pPC) - driving force for reabsorption
  2. Hydrostatic pressure in peritubular capillary (PPC) - force that prevents water from entering capillary
  3. Hydrostatic pressure in interstitial space (Pi / Po) - H2O follows solutes – increase pressure – forces H2O into capillary
20
Q

If the GFR is too high:

A

Needed substances cannot be reabsorbed quickly enough and are lost in the urine

21
Q

If the GFR is too low:

A

Everything is reabsorbed, including wastes that are normally disposed.

22
Q

………. maintains a nearly constant GFR when mena arterial blood pressure is between 80-180 mmHG.

A

Autoregulation

23
Q

Effects of the myogenic response of autoregulation:

A

Increased arterial pressure stretches smooth muscle in blood vessel walls induces constriction of afferent arteriole;

24
Q

Effects of the Tubuloglomerular Feedback of autoregulation:

A

Involves macula densa and vasoactive substances (adenosine, kinins, PGs) to constrict/dilate afferent/efferent arteriole