Renal Introduction - RS Flashcards
What are the regulatory functions of 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.
What relationship does TBW have with fat?
An inverse one. As fat increases TBW decreases.
Is the composition of ICF and ECF the same? What about the concentration or osmolarity?
The composition is NOT the same, however, the concentration/ osmolarity is the same.
What is the %of Body Weight that is TBW? What % is ECF? What is ICF? What about intravascular fluid?
60%. 40%. 20%. And about 7% is intravascular fluid.
What is the formula for Starling’s law?
Filtration or Reabsorption Rate = Lp [(PC – Pi) – (πC – πi)]
Lp is greatest in the kidney. Meaning that per unit force there is the greatest filtration
What is the main contributor to plasma oncotic pressure? How does it compare to the interstitial fluid?
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.
Does hydrostatic pressure affect plasma membrane fluid uptake?
Cell membranes are deformable and dissipate hydrostatic pressure across the cell membrane by a change in cell shape, without movement of water across the membrane (filtration). Accordingly, the net movement of water between intracellular (ICF) and extracellular fluid (ECF) is driven only by osmotic pressure differences across the cell membrane and is referred to as Osmosis.
What happens to ICF and ECF with isosmotic fluid expansion?
The ECF increases in volume but the ICF remains the same. There is a dilution of plasma proteins and decrease in Hcrt.
What happens in isosmotic fluid loss such as diarrhea?
The ECF decreases in volume but the ICF remains the same. There is hemoconcentration of proteins.
What happens in Profuse sweating and/or water deprivation – loss of water in excess of solute from the ECF?
Hyperosmotic Volume Contraction: There is a decrease in ECF volume and an increase in ECF osmolarity. Water moves from ICF to ECF. The ICF will also decrease in volume and increase in osmolarity.
What happens in High NaCl intake without fluids – gain of solute in excess of water in the ECF?
Hyperosmotic Volume Expansion: There is an increase in ECF osmolarity, water moves from ICF to ECF, an increase in ECF volume, decrease ICF volume and increase ICF osmolarity.
With a high salt intake what happens to ICF [Na]?
An increase in plasma [Na] secondary to high Na consumption, is buffered, initially, by increased cellular uptake of the excess Na consumed. However, this does not increase ICF [Na] because an increase in Na/K ATPase activity (Na extrusion) balances increased cellular Na uptake.
What happens in Syndrome of Inappropriate Antidiuretic Hormone (SIADH) – gain of water in excess of solute in the ECF?
Hypoosmotic volume expansion: Excess water reabsorption in the collecting duct causes an increase in ECF volume and decrease in ECF osmolarity. Water moves from ECF to ICF with an increase in ICF volume and decrease in ICF osmolarity.
What happens in Adrenal (Aldosterone) insufficiency – “salt wasting”, loss of solute in excess of water from the ECF to the urine?
Hypoosmotic volume contraction: decreased renal tubule NaCl reabsorption and return of NaCl to the ECF, decrease in ECF osmolarity, water moves from ECF to ICF, decrease in ECF volume, Increase ICF volume and decrease in ICF osmolarity.
Cells initially shrink in response to an increase in ECF osmolarity, what do the cells do to return to homeostasis?
Cells activate solute uptake mechanisms to increase ICF osmolarity driving water back into the cells. The is regulatory volume increase (RVI). When giving fluid to a patient who has undergone cellular RVI there is the potential for dangerous cell swelling.
