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SF 3 - Test 3 > 1 - Glomerular Filtration 1 > Flashcards

1 - Glomerular Filtration 1 Flashcards

1
Q

Objectives: Explain the general functions of the kidney

A
  • Regulation of water and electrolyte balance
  • Removal of waste from blood, excrete in urine
  • Remove foreign chemicals from blood, excrete
  • Regulation of BP by altering sodium excretion, and the secretion of renin
  • Secretion of erythropoietin
  • Secretion of 1,25-dihydroxyvitamin D3
  • Gluconeogenesis
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2
Q

Objectives: Explain important gross structure of the kidneys

A
  • Cortical and medullary substance, pelvis connects to ureter
  • Medulla subdivided into an inner and outer section
  • Microscopic functional unit is nephron
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3
Q

Objectives: Explain the relationships between components of the nephron

Bowman’s Capsule

Bowman’s Space

Glomerulus

Glomerular Mesangial Cells (2)

Glomerular Membranes (3)

A
  • Bowman’s Capsule
    • Expanded blind end of uriniferous tubule
  • Bowman’s Space
    • Area receiving filtrate of blood
  • Glomerulus
    • Tuft of capillaries within Bowman’s Capsule
  • Glomerular Mesangial Cells (2)
    • Phagocytic - “clean” glomerular membranes, keep functional
    • Nonphagocytic - Contractile Cell to regulate surface area for filtration
  • Glomerular Membranes (3)
    *
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4
Q

Objectives: Explain basic renal processes

Glomerular Filtration

Tubular Secretion

Tubular Reabsorption

A
  • Glomerular Filtration - bulk flow of protein-free plasma from glomerular capillaries into Bowman’s Capsule
    • No Active Tx
    • Permeability selective (Water Good, Hb/Protein Bad)
  • Tubular Secretion - Tx of materials from peritubular-capillary plasma to tubular lumen
    • Highly Selective
    • Active & Passive tx
    • Occurs through length of nephron
  • Tubular Reabsorption - Tx of materials from lumen of tubule to the peritubular-capillar plasma
    • Highly Selective
    • Active & Passive tx
    • Occurs through length of nephron
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5
Q

Objectives: Explain the relationship between flow, resistance, and pressure in kidneys

A
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6
Q

Objectives: How is glomerular filtrate formed, and what forces determine its rate of formation?

Equation?

Changes to Kf

A
  • Equation: GFR = Kf x (PC - PB - πC)
    • Kf = Ultrafiltration Coefficient (LP x A)
    • PC = Capillary Pressure
    • PB = Bowman’s Pressure
    • πC = Avg. Colloid osmotic pressure
  • Changes to Kf - Changes w/vasoactive substances, and pathologic conditions​
    • ​Vasoactive:
      • ​Increased [ADH], Angiotensin II (ANG II) - Intrarenal mesangial cells contract; lower SA, lower Kf, lower GFR
      • Atrial Natriuretic Peptide (ANP) - Intrarenal mesangial cells relax, increase SA, increase Kf, increase GFR
    • Pathologic:
      • ​Filtration barrier can be thickened
      • Glomerular capillaries can be destroyed, causing decrease in SA
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7
Q

Objectives: How is glomerular filtrate formed, and what forces determine its rate of formation?

Equation

Changes to vessels

A
  • Equation: GFR = Kf x (PC - PB - πC)
    • Kf = Ultrafiltration Coefficient (LP x A)
    • PC = Capillary Pressure
    • PB = Bowman’s Pressure
    • πC = Avg. Colloid osmotic pressure
  • Afferent Artery (AA): Changes to resistance cause RBF/GFR to change in SAME direction
    • E.g. ​Increase resistance, decrease RBF, decrease GFR
  • Efferent Artery (EA): Changes to resistance cause RBF/GFR to change in OPPOSITE direction
    • ​E.g. Increase resistance, decrease RBF, increase GFR
  • These can be combined: Efferent constriction could be added to afferent constriction to further inhibit RBF and enhance GFR, thus increasing FF
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8
Q

Objectives: How is glomerular filtrate formed, and what forces determine its rate of formation?

Equation

Changes to PB

Changes to πC

A
  • Equation: GFR = Kf x (PC - PB - πC)
    • Kf = Ultrafiltration Coefficient (LP x A)
    • PC = Capillary Pressure
    • PB = Bowman’s Pressure
    • πC = Avg. Colloid osmotic pressure
  • PB required to drive flow of urine along nephrone
  • PB​ increases with increased urine flow
    • Ex: Diuretics cause decrease in GFR
  • PB​ may increase in pathological obstruction of the tubules
    • ​Ex: Kidney stones cause decrease in GFR
  • Pc: As protein free fluid is filtered from the flomerular capillary plasma, protein concentration of the remaining plasma increase –> increase colloid osmotic pressure
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9
Q

Objectives: Explain normal control of RBF and GFR

A
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10
Q

Objectives: Define autoregulation of RBF and GFR

A
  • From 80 - 180 mmHg, both GFR and RBF are maintained relatively constant
  • Two Mechanisms:
    • ​Myogenic Mechanism
      • ​ΔP in arterioles is primary stimulus; in response to stretch, smooth muscles contract
    • Tubuloglomerular Feedback Mechanism
      • ​After increase to RBF & GFR, Macula Densa senses increased Na/Cl delivery
      • Releases Vasoactive Substrance (adenosine); increaes constriction in Afferent Arteriole
      • End Result: Decrease in RBF & GFR
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11
Q

Identify the important structures

A
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12
Q

Clinical: Explain Glomerulonephritis

A
  • Glomerulonephritis - Renal disease with bilateral inflammatory changes in glomeruli; potential deficiency in kidney membrane proteins
    • Decreased urine
    • Blood/Protein in Urine
    • Edema
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13
Q

Clinical: Nephrotic Syndrome

A
  • Nephrotic Syndrome: Nonspecific disorder with:
    • Symptoms:
      • Severe proteinuria
      • Hypoalbuminemia
      • Hyperlipidemia
      • Edama
    • Cause:
      • Damage to glomeruli
      • Slit Diaphraph Protein gene mutations
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14
Q

Clinical: Nephritic Syndrome

A
  • Nephritic Syndrome: Non-specific diagnosis, characterized by:
    • Symptoms:
      • Edema
      • Hypertension
      • Hematuria
      • Elevated serum creatine
      • Azotemia (increased BUN)
      • Oliguria (low urine output)
        *
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15
Q

Explain the tubule system within the nephron

A
  • Proximal Tubule - Connected to Bowman’s Capsule
    • ​Major site of reabsorption of filtered fluid
    • Distinguied by large surface area
    • Membranes:
      • Apical - Microvilli, bulges into tubular lumen
      • Basolateral - Non-tight junctions; allows channel; mitochondria line membrane of prox. tubular cells
  • Henle’s Loop - Resuls in countercurrent direction of flow
    • Allows descending/ascending interactions
  • Distal Tubule - Returns to cortex, makes contact with afferent/efferent arterioles
    • Site of Juxtraglomerular Apparatus (JGA)
    • Shorter section
    • Impermeable to water
  • Collecting Tubule System - Receives tubular fluid from distal tubules; “fine tuning” of tubular fluid composition
    • Lined by: Principal Cells: ADH, ANP, Aldosterone
    • Lined by: Intercalated Cells: H+ Secretion (a-cells), HCO3- secretion (b-cells)
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16
Q

Explain the JGA (3 cell types)

A
  • Consists of 3 cell types:
    • Macula Densa Cells - In late ascending limb, early distal tubule
      • Volume/Flow/[NaCl] of tubular fluid
    • Granular Cells (smooth m.) - In walls of afferent / efferent arteriole
      • ​Secrete RENIN
    • Extraglomerular (mesangial) Cells
      • Phagocytic Activity
      • Communicate w/Granular cells via gap jx’s
17
Q

Explain the two types of nephrons

A
  • (7/8) Cortical (Superficial) Nephrons:
    • Glomeruli lie in outer 2/3 of cortex
    • Short Loops of Henle
    • NO think ascending loop of Henle
  • (1/8) Juxtamedullary Nephrons:
    • Glomeruli lie in inner 1/3 of cortex and are larger than Cortical variant
    • Long Loops of Henle
    • # of Juxtamedullary nephrons and Loops of Henle directly correlate with capacity to make concentrated urine
18
Q

Explain the nerve supply to the kidney

A
  • Vagal Innervation absent
  • Sympathetics:
    • ​Vasoconstriction
    • Granular Cells -> (+) Renin Secretion
    • Activation of prox. tubule, loop of Henle, distal tubule, and collection duct = (+) Sodium Reabsorption
19
Q

Explain the Lymphatic network within the Kidney

A

Network drains Cortex only

20
Q

How does one determine Filtration Fraction?

A
  • FF = GFR / RPF
  • FF = Filtration Fraction
  • GFR = Glomerular Filtration Rate
  • RPF = Renal Plasma Flow
21
Q

What major hormones increase GFR?

What major hormones decrease GFR?

A
  • Increase: ADH, ANG II
  • Decrease: ANP

SF 3 - Test 3 (12 decks)

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