62: Intro to Renal Phys Flashcards
The units of measure quantifying osmolarity are scaled to units of volume of solvent (water) containing solutes ____.
The units of measure quantifying osmolality are scaled to units of weight of the solvent (water) and the solutes contained in the solvent _____.
The units of measure quantifying osmolarity are scaled to units of volume of solvent (water) containing solutes (mOsmoles / Liter).
The units of measure quantifying osmolality are scaled to units of weight of the solvent (water) and the solutes contained in the solvent (mOsmoles / Kg).
The kidney performs a homeostatic regulatory function maintaining extracellular fluid _____, osmol__ity and ion _____, which supports function of the cardiovascular system maintaining adequate blood pressure and blood flow. The regulatory function of the kidney is what it does “outside” the kidney by doing what it does “inside” the kidney.
The kidney performs a homeostatic regulatory function maintaining extracellular fluid volume, osmolarity and ion composition, which supports function of the cardiovascular system maintaining adequate blood pressure and blood flow. The regulatory function of the kidney is what it does “outside” the kidney by doing what it does “inside” the kidney.
For a 70 Kg patient:
TBW: 60% body weight = __Kg
ICF: 40% body weight = __Kg
ECF: 20% body weight = __Kg
Hematocrit = __%, the volume the kidney sees
TBW: 60% body weight = 42 Kg
ICF: 40% body weight = 28 Kg
ECF: 20% body weight = 14 Kg
Hematocrit = 55%, the volume the kidney sees
Inside cell major composition:
Inside: _____
Outside: _____
Na/K ATPase maintains ____
Despite differences in ionic composition from inside & outside the cell, concentration of both sides is the same @ ___ mOsm.
Inside cell major composition:
Inside: potassium
Outside: sodium
Na/K ATPase maintains gradient
Despite differences in ionic composition from inside & outside the cell, concentration of both sides is the same @ 290 mOsm.
______ is the main step in excretion.
Consumption is the main step in excretion.
The kidneys are the only effector organs of regulated water and salt excretion. Unregulated water and salt loss:
- sweat = loss of _____
- feces = loss of ______
- insensible skin and lung loss of ______
The kidneys are the only effector organs of regulated water and salt excretion. Unregulated water and salt loss:
- sweat = loss of water & salt
- feces = loss of water & salt
- insensible skin and lung loss of water
Across the capillary from the arteriolar and venous end, fluid distribution is driven by the balance between hydrostatic pressure and osmotic pressure differences.
Filtration or Reabsorption rate = ________
Filtration or Reabsorption rate = (35-1) - (25-2) = 13 so _____ pressure is higher & it pushes out while less oncotic pressure brings fluid in.
Across the capillary from the arteriolar and venous end, fluid distribution is driven by the balance between hydrostatic pressure and osmotic pressure differences.
Filtration or Reabsorption rate = Lp [(Pc-Pi)] - [(pic-pii)] = push out - push in
Filtration or Reabsorption rate = (35-1) - (25-2) = 13 so hydrostatic pressure is higher & it pushes out & oncotic pressure brings fluid in.
Net filtration or reabsorption will occur along the length of the capillary depending on the balance of forces favoring filtration or reabsorption. As shown above, arteriole to venous blood flow through the capillaries occurs with filtration of intravascular fluid at the arteriole end where the forces driving filtration (hydrostatic pressure) exceed the forces opposing filtration (oncotic pressure) and with reabsorption of extravascular fluid at the venous end where the forces driving reabsorption (oncotic pressure) exceed the forces driving filtration (hydrostatic pressure).
Plasma “oncotic” pressure is the osmotic pressure of the plasma attributed to the presence of ______ charged proteins (albumin) in the plasma. The “oncotic” pressure of the ISF is very low due to the relative ______ of protein in the ISF.
Plasma “oncotic” pressure is the osmotic pressure of the plasma attributed to the presence of negatively charged proteins (albumin) in the plasma. The “oncotic” pressure of the ISF is very low due to the relative absence of protein in the ISF.
ICF & ECF water differences are driven by ______ pressure differences. Water moves passively across the cell membrane in a direction down its concentration gradient from the side of higher water concentration (_____ tonicity) to the side of lower water concentration (_____ tonicity) through the lipid bilayer or through protein water channels (aquaporins) spanning the lipid bilayer.
ICF & ECF water differences are driven by osmotic pressure differences. Water moves passively across the cell membrane in a direction down its concentration gradient from the side of higher water concentration (lower tonicity) to the side of lower water concentration (higher tonicity) through the lipid bilayer or through protein water channels (aquaporins) spanning the lipid bilayer.
ADH reabsorbs ______ in the collecting duct.
ADH reabsorbs water in the collecting duct.
Aldosterone reabsorbs _____ and water follows sodium.
Aldosterone reabsorbs sodium and water follows sodium.
See pg. 89-94
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Cell shrinkage in response to an increase in ECF osmolarity—cells activate solute ______ mechanisms to ____ ICF osmolarity to drive water into cells & restore volume to normal = regulatory volume increase.
Cell swelling in response to a decrease in ECF osmolarity—cells activate solute _____ mechanisms to _____ ICF osmolarity, driving water out of cells to restore volume to normal.
Cell shrinkage in response to an increase in ECF osmolarity—cells activate solute uptake mechanisms to increase ICF osmolarity to drive water into cells & restore volume to normal = regulatory volume increase.
Cell swelling in response to a decrease in ECF osmolarity—cells activate solute efflux mechanisms to decrease ICF osmolarity, driving water out of cells to restore volume to normal.
Exercise caution when attempting to restore ECF osmolarity to normal—dangerous cell shrinkage or swelling may occur.
Cells possess the ability to regulate and maintain intracellular volume, independent of changes in extracellular volume and osmolarity. This is, again, another example of homeostasis. Cells are able to defend against the effects of changes in ECF osmolarity, which, if not compensated for, will swell or shrink cell volume. Consider the dire consequences of a variable cell volume in terms of the concentration of the multitude of intracellular metabolites, where the rates of metabolic reactions are dependent upon the concentration of substrates and the affinity (Km) of substrates for enzyme-mediated metabolism.
FILTRATION: The ultrafiltration of blood through glomerular capillaries excludes cells and large proteins from the filtrate. The ultrafiltrate is collected in Bowman’s space and contains organic and inorganic solutes at concentrations ______ to plasma. Glomerular Filtration Rate (GFR) is approximately ___ ml/min or __L/day and is the sum filtration across all the glomeruli of 1 million nephrons in each kidney.
FILTRATION: The ultrafiltration of blood through glomerular capillaries excludes cells and large proteins from the filtrate. The ultrafiltrate is collected in Bowman’s space and contains organic and inorganic solutes at concentrations similar to plasma. Glomerular Filtration Rate (GFR) is approximately 125 ml/min or 180L/day and is the sum filtration across all the glomeruli of 1 million nephrons in each kidney.
REABSORPTION: The movement of solutes and water from the tubular fluid in the lumen of the kidney tubule to the _____ surface (blood side), and into the ______ capillaries.
REABSORPTION: The movement of solutes and water from the tubular fluid in the lumen of the kidney tubule to the peritubular surface (blood side), and into the peritubular capillaries.
