Intro to Renal Physiology Flashcards
Filtration or Reabsorption Rate
= Lp [(Pc-Pi)-(πc-πi)]
What is edema? What causes it?
Excess accumulation of fluid in the interstitial space due to cardiac, renal, hepatic, or endocrine dysfunction
- CHF, nephrotic syndrome, liver disease can cause an isotonic retention of sodium and water as well as decreased circulating volume, which can decrease renal perfusion pressure and activate R-A-A system, further increasing sodium retention, maintaining edema.
What causes the net movement of water between ICF and ECF?
Osmotic pressure differences across the cell membrane (from low to high tonicity)
What happens to ICF and ECF volume when a volume of ISOTONIC solution is added to the ECF?
Example: intravenous isotonic fluid gain to ECF
- increase in ECF volume, N/C in ECF osmolarity
- no driving force between ICF and ECF
- N/C in ICF volume or osmolarity
- dilution of plasma proteins, decrease Hct
What happens to ICF and ECF volume when a volume of ISOTONIC solution is subtracted from the ECF?
Example: diarrhea, isotonic fluid loss from ECF
- decrease in ECF volume, N/C in ECF osmolarity
- no driving force between ICF and ECF
- N/C in ICF volume or osmolarity
- concentration of protein and increased Hct
What happens to ICF and ECF volume and osmolarity when a relatively dilute solution or volume containing water in excess of solute is subtrated from the ECF?
Example: profuse sweating or water deprivation
- Decrease in ECF volume and increase in ECF osmolarity
- water moves from ICF to ECF
- Decrease in ICF volume and increase in ICF osmolarity
What happens to ICF and ECF volume and osmolarity when a relatively concentrated solution or volume containing solute in excess of water is added to the ECF?
Example: High NaCl intake without fluids
- Increase in ECF osmolarity
- water moves from ICF to ECF
- Decrease ICF volume and increase ICF osmolarity
- Increase ECF volume
- ICF Na and Cl concentration is unchanged due to Na-K pump balancing Na entry
What happens to ICF and ECF volume and osmolarity when a relatively dilute solution or volume containing water in excess of solute is added to the ECF?
Example: Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
- Increase in ECF volume, decrease in ECF osmolarity
- water moves from ECF to ICF
- Increase in ICF volume, decrease in ICF osmolarity
What happens to ICF and ECF volume and osmolarity when solute in excess of water is subtracted from the ECF?
Example: Adrenal insufficiency (“salt wasting”)
- Decrease ECF osmolarity
- water moves from ECF to ICF
- Increase ICF volume and decrease ICF osmolarity
- Decrease ECF volume
What solute is high inside the cell and what is high outside the cell?
Na+-K+ ATPase maintains intracellular K+ high and extracellular Na+ high
OSMOLARITY IS THE SAME
How do cells respond to increase or derease in ECF osmolarity?
INCREASE: cell shrinks
DECREASE: cell swells
Filtration
The anatomical separation of an ultrafiltrate from the blood
Reabsorption
The directional movement of solutes and water from the lumen of the kidney tubule to the peritubular surface
Secretion
The directional movement of solutes (not water) from the peritubular side of the kidney tubule to the lumenal surface
Synthesis
Metabolism within kidney cells degrades and creates organic solutes or homones appearing in the blood or urine (NH4+, HCO3-, renin, erythropoietin, active vitamin D)
