Intro to renal Flashcards
What does the kidney help regulate, and what doe this regulated function help maintain?
ECF volume, osmolarity, fluid ion composition (Na, K, H, bicarb); helps maintain blood pressure and blood flow
What two other features does the kidney partake in?
Clearance of metabolic end products, toxins and drugs; endocrine includes EPO, active vit D, renin
With a standardized patient of 70 kg, what is the percent of weight that is total body water (TBW)? How much is ECF and ICF percentage-wise?
60% (42L); 40% is 28 L; 20% is 14 L
What two components make up the ICF?
Plasma (3 L) and extravascular fluid (10 L, interstitial fluid)
What is TBW proportional to?
Inversely proportional to percent body fat
How is the osmolarity of the ICF compared to the ECF?
The solute concentration is essentially the same
What is the only effector organ of regulated water and salt excretion?
Kidneys
When does unregulated water and salt loss from TBW occur?
Sweat, feces, insensible skin and lung loss (water only)
What can the kidneys do given variable consumption of solutes and water on ECF volume and osmolarity?
They increase or decrease excretion of solutes and water in the urine given how much solute or water is consumed
What drives filtration of fluid out of the arterial end? What drives absorption closer to the venous end?
Hydrostatic pressure being greater than oncotic pressure (osmotic pressure in and out of capillary due to protein present or not);
The hydrostatic pressure drops and oncotic pressure is greater
What has the greater filtration rate, the glomerular or systemic capillaries?
Glomerular capillaries because of a higher Lp
How does CHF cause edema?
It raises the capillary hydrostatic pressure at the venous end
Nephrotic syndrome and liver disease cause edema how?
They decrease plasma protein concentration and capillary oncotic pressure; cause isotonic retention of sodium and water as well as decreased circulating volume
What determines water movement across the cell membrane? What type of movement does water undergo, active or passive? What does water do relative to solute?
Permeating and non-permeating solute concentrations in the ICF and ECF; passive;
water follows solute, with the latter being transported actively or passively
How does water move across its cell membrane?
From higher concentration to lower concentration through the lipid bilayer or aquaporins
What happens to ECF volume, ECF osmolarity, ICF volume and osmolarity with IV isosmotic fluid gain to the ECF? Crit and protein levels?
Increase, no change, no change, no change
What happens to ECF volume and osmolarity, ICF volume and osmolarity with isosmotic fluid loss? Crit and protein levels?
Decrease, no change, no change, no change; protein and crit increased
What happens to ECF volume, ECF osmolarity, ICF volume and ICF osmolarity due to sweating and/or water deprivation?
Decreases, increases, decrease, increase
What happens to the ECF osmolarity, ICF volume and ICF osmolarity, and ECF volume with high NaCl intake without fluids? What happens to ICF Na concentrations? Why?
Increases, decreases, increase, increase;
They remain unchanged due to Na-K pump activity balancing Na entry
What happens with ECF volume, ECF osmolarity, ICF volume and ICF osmolarity given syndrome of inappropriate ADH (SIADH)?
Increase, decrease, increase, decrease
What happens with ECF osmolarity, ICF volume and ICF osmolarity and ECF volume when there is adrenal insufficiency and decreased renal NaCl reabsorption?
Decrease, increase, decrease, decrease
What happens to a cell in response to increases in ECF osmolarity? What’s this process called?
Cells activate uptake mechs to increase ICF osmolarity to drive water into the cells; regulatory volume increase!!!
What happens to a cell in response to decreases in ECF osmolarity? What’s this process called?
Cells activate efflux mechs to decrease ICF osmolarity to drive water out of cells (regulatory volume decrease)
What do you have to watch out for when trying to restore ECF osmolarity to normal?
A high rate of infusion may cause dangerous cell swelling if RVI had previously occurred, or dangerous cell shrinking if RVD had occurred
What is the main consequence of variable cell volume?
Concentration of intracellular metabolites changes, and that could affect metabolic reactions dependent on substrate concentration and substrate affinity for enzymes
What are the basic processes of the kidney? What process is NOT a renal process?
- Filtration (ultrafiltrate made with organic and inorganic solutes at concentrations similar to plasma)
- Reabsorption (moving solutes and water from kidney tubule lumen to peritubular surface)
- Secretion (movement of ONLY solutes from peritubular side to the lumen)
- Synthesis (Hormones/organic solutes made/degraded that appear in blood or urine, like ammonium, bicar, renin, EPO, active vit D)
Excretion (amount of solute and water eliminated in urine)
How are solutes and water handled by the kidney? What about those NOT metabolized by the kidney?
Excreted = Filtered + Secreted + Synthesized - Reabsorbed;
Same as above but remove the synthesized part
What are three main components of renal function? Which blood supply takes care of filtration and reabsorption? Where does this process start and end?
- Glomerular filtration
- Tubular secretion
- Tubular reabsorption;
the same blood supply;
Proximal tubule and collecting duct
