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27 Cards in this Set
- Front
- Back
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Name three functions of the kidney
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1.electrolyte balance
2.acid-base balance 3.regulation of normal fluid volume and osmolarity 4.excretion of wastes 5.long-term control of BP 6.synthesis and release of renin |
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How is molarity defined? How is molality defined?
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*Moles solute/liter of solution
*Moles solute/kilogram of solution |
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What are the normal concentrations of NaCl, KCl, and glucose?
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*NaCl = 140mM (140meQ/L)
*KCl = 3.5-5.0meQ/L *glc = 5mM (80-100mg/dL) |
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What is the formula for osmolarity? How is osmolarity related to the concentration of water?
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*Osm = molar concentration x number of dissociable particles
*osmolarity represents the inverse of water concentration |
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What is the normal value for the colloid osmotic pressure of plasma?
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*25mmHg
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How is total body water calculated? What is a normal value for a 70-kg man? How is total body water divided between the extracellular and intracellular compartments?
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*weight (kg) x fraction of water
*42 L *2/3 in the intracellar compartment (28L), 1/3 in the extracellular compartment (14L) |
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How is the extracellular fluid compartment divided between the plasma and interstitial fluid?
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*3/4 as interstitial fluid (10.5L)
*1/4 as plasma (3.5L) |
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What is the normal osmolarity of ECF and ICF? Which is at greater risk for change and why?
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*285-300mOsm
*ECF, because it is subject to external influences |
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There are 2 ways that isosmolar can be defined - what are they?
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*two solutions having the same osmolarity
*a solution that has the same osmolarity as plasma |
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How does a hyposmolar solution affect cells? What about a hyperosmotic solution?
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*In a hyposmotic solution, water will run into cells and cause them to swell and lyse
*In a hyperosmotic solution, water will flow out of the cell causing it to shrink |
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How does water loading affect the osmolarity and volume of ECF and ICF?
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It will cause a decrease in the osmolarity and an increase in the volume of ICF and ECF.
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How does salt loading affect osmolarity and volume of ICF and ECF?
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*increases the osmolarity of ECF and ICF
*decreases the volume of ICF *increases the volume of the ECF |
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How does an infusion of isosmolar solution affect the volume of the ECF and ICF?
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This causes an increase in the volume of the ECF only.
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In terms of the steady state, what is meant by positive balance? Negative balance?
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*positive balance means that intake exceeds output
*negative balance means that output exceeds intake |
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How many juxto-medullary nephrons are there relative to the number of cortical nephrons?
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There are around nine times as many cortical nephrons as there are juxto-medullary ones.
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What is meant by ultrafiltration?
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Fluid is moved from the glomerular capillaries to Bowman's space.
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What is meant by reabsorption?
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Fluid is moved from the tubule lumen into the plasma.
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What is meant by secretion? Excretion?
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*Fluid is moved from the plasma to the tubule lumen
*fluid is moved from the tubule lumen out of the body |
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Describe (in general terms) the action of the PCT - is it reabsorptive or secretory? What solutes are affected and how?
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The PCT resorbs 2/3 of all filtered water and NaCl, all filtered glucose, and secretes drug metabolites.
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T/F:
The descending LOH reabsorbs water and NaCl. |
False: the descending LOH reabsorbs water but secretes NaCl.
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What is the action of the ascending LOH on water?
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It is impermeable to water and thus has no effect. It does reabsorb NaCl though.
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How are the DCT and collecting ducts affected by ADH and aldosterone?
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*they reabsorb water under the influence of ADH
*they reabsorb Na+ and secrete K+ under the influence of aldosterone |
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Renal blood supply consumes roughly what percentage of cardiac output?
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25%
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How is renal blood flow divided between the cortex and medulla?
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The cortex receives ~90% while the medulla receives only ~10%.
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What is the pressure in the glomerular capillaries? How does this compare to pressure in systemic capillary beds? What is the advantage of this?
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*60mmHg
*much higher (systemic is 15-20mmHg) *drives filtration |
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What is the pressure in the peritubular capillaries? Of what advantage is this?
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It is normal (close to 15-20mmHg). This favors reabsorption.
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Does osmolarity take into account all particles in a solution?
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No - it pertains only to those that do not freely cross the membrane.
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