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44 Cards in this Set
- Front
- Back
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Properties of H2O
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Temperature
High Heat Capacity High Heat of Vaporization Good Heat Conductor (for a liquid) Large Range Freezing to Boiling points Solvent Dissolves Largest # of compounds High dielectric constant Self ionizes High Surface Tension “States” of water |
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Effect of Water Content on age and sex
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% Body Wt./TBW decreases with age and and women have smaller %then men
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Water Balance
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intake must = output
2,750 (mls. / day) |
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Volumes of Water Compartments
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Intracellular 30-40% 25 L
Interstitial 16% 11 L Plasma 4% 3 L Transcellular 1-3% 2L |
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Rules for Compartment Volumes
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Compartments Equilibrate Osmotically
# of particles determines relative Volume of compartments Na+ confined to ECF, amount varies K+ confined to ICF ~ amount constant Total ICF solute content remains constant Disturbances start in ECF |
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General Renal Functions
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1.Maintain body fluid volume
2. Maintain body fluid composition 3. Produce hormones : renin, angiotensin, erythropoietin, Vitamin D 4. Provide energy: gluconeogenesis |
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Steps of Nephron Function
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Glomerular Filtration
Tubular Fluid Modification |
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Determinants of Filtration
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Molecular
Size (<5,000 daltons = filtered; >75,000 daltons unfiltered) Shape (round > straight),Charge (positive > negative) Pressure Permeability |
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Regulation of Filtration and Blood Flow
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Afferent arteriole and Efferent arteriole
GFR = Kf . [ Pg - ( Pbs+ pg )] |
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Regulation of Glomerular Arterioles
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Myogenic mechanism Afferent art. only
alpha1-adrenergic Afferent art. only Angiotensin II Efferent art. primarily Tubuloglomerular feedback 1 Afferent art. primarily |
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Properties of H2O
|
Temperature
High Heat Capacity High Heat of Vaporization Good Heat Conductor (for a liquid) Large Range Freezing to Boiling points Solvent Dissolves Largest # of compounds High dielectric constant Self ionizes High Surface Tension “States” of water |
|
|
Effect of Water Content on age and sex
|
% Body Wt./TBW decreases with age and and women have smaller %then men
|
|
|
Water Balance
|
intake must = output
2,750 (mls. / day) |
|
|
Volumes of Water Compartments
|
Intracellular 30-40% 25 L
Interstitial 16% 11 L Plasma 4% 3 L Transcellular 1-3% 2L |
|
|
Rules for Compartment Volumes
|
Compartments Equilibrate Osmotically
# of particles determines relative Volume of compartments Na+ confined to ECF, amount varies K+ confined to ICF ~ amount constant Total ICF solute content remains constant Disturbances start in ECF |
|
|
General Renal Functions
|
1.Maintain body fluid volume
2. Maintain body fluid composition 3. Produce hormones : renin, angiotensin, erythropoietin, Vitamin D 4. Provide energy: gluconeogenesis |
|
|
Steps of Nephron Function
|
Glomerular Filtration
Tubular Fluid Modification |
|
|
Determinants of Filtration
|
Molecular
Size (<5,000 daltons = filtered; >75,000 daltons unfiltered) Shape (round > straight),Charge (positive > negative) Pressure Permeability |
|
|
Regulation of Filtration and Blood Flow
|
Afferent arteriole and Efferent arteriole
GFR = Kf . [ Pg - ( Pbs+ pg )] |
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|
Regulation of Glomerular Arterioles
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Myogenic mechanism Afferent art. only
alpha1-adrenergic Afferent art. only Angiotensin II Efferent art. primarily Tubuloglomerular feedback 1 Afferent art. primarily |
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Clearance
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equivalent volume of plasma that is completely cleared of a substance / unit time
inulin clearance = GFR Cin = Uin x V / Pin = GFR |
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Functions of Nephron Segments
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PCT Filtrate reabsorption
PR Organic ion secretion tDL H2O permeable tAL Salt permeable TAL Active salt absorption (NaKCC) DCT Active salt absorption (ENaC) CD +/- H2O permeable (ADH) |
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Transport maximums
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Absorption Tm :
amt. absorbed = amt. filtered - max. amt. excreted Secretion Tm : amt. secreted = max. amt. excreted - amt. filtered |
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Isotonic Coupling Concept
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No NaCl concentration gradients
No Back leak Unlimited Isotonic fluid absorbed |
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Pump / Backleak Concept
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Pump rate out = Back leak in
steady state no ↓tubular fluid vol. |
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Osmotic Trapping Concept
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Pump Rate = Back Leak
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counter current multiplier
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amplifies and converts a transepithelial osmotic gradient into a larger axial gradient in the nephron.t
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Determinants of Max Concentration
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Max supportable horizontal gradient
Length of counter current tubes Flow rate |
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Renal role of urea
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Water leaves early DC concentrating urea which then exits from late DC and enters tAL increasing its urea concentration. With each cycle of urea, urea becomes more concentrated until it contributes about 1/2 of the osmolality (i.e.; 600-700 mOsm/L) of the medullary interstitium and papillary regions of the kidney.
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Counter Current Exchange (vasa recta)
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osmotically equilibrates opposite flows to preserve axial gradients in the system
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Urea Cycle
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traps urea in the medullary space to enhance interstitial osmolality for concentrating urine
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Collecting Duct: Type B intercalated cells
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Secrete HCO3-
Alkalinize the urine |
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Collecting Duct: Type A intercalated cells
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Absorb K+
Secrete H+; acidify the urine |
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Collecting Duct: Principal Cell
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Na+ absorption
Aldosterone ~ 2% Filtered load K+ secretion H20 absorption + ADH |
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Distal Convoluted Tubule Cell
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NaCl Absorption: 5% Filtered
Load dependent (ADH insensitive) Ca++ Absorption |
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Thick Ascending Limb
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Cation Uptake
Na+ Absorption; 25% Filtered load Load Dependent Mg++, Ca++ Absorption |
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Main determinates of Fluid Absorption in PCT
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Na/H exchange
HCO3- impermeability Peritubular oncotic pressures |
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Glomerular Tubular Balance
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2/3 of filtered load reabsorbed by the PCT
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Osmotic Diuresis
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unabsorbed solutes trap fluid in the PCT
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Tubular Transport Maximums
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determined from amount excreted and plasma concentrations (absorption or secretion)
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Tubular Glomerular Feedback
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matches filtration rate to tubular flow in each nephron
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Hydraulic and Oncotic forces
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determine Fluid Filtration rate
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nephron
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manages fluid and solute homeostasis via plasma filtration and fluid modification
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Darrow Diagrams
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assists in analysis of fluid disturbances
- 6 rules for H2O distribution between compartments - 6 types of fluid disturbances - fluid volume shifts can be calculated from changes in osmolality (solute content) of compartments and body weight changes |
