RAAS. Dialysis Flashcards
What are the triggers for Renin release?
Low blood pressure, sympathetic nervous cell, low Na in the distal convulted tubule
Where is renin released
Relased from the JuxtaGlomerular cells (smooth muscle cells)
How is the macula densa involved in renin release?
In distal tubule of nephron, senses low Na (low bp leads to less Na). Stimulated via local PGs
Where is angiotensinogen made
Liver cells. Not active.
Combines with renin
Where is ACE found?
Blood vessels and lungs
List the sites of angiotensin II active
Smooth muscle of blood vessels- constriction
Kidney- water rention, increase GFR by vasconstriction of efferent
Pituitary Gland ADH release
Adrenal Gland- Aldosterone release
How are volume and osmolarity affected with aldosterone versus ADH
Aldosterone: Increase in volume with no change in osmolarity as porportional change
ADH: Inverserly related if volume increased Osmolarity decreases
Where is aldosterone made and why
Made from cholesterol in the adrenal cortex. Stimulated by Angiotensin II and increased K+
Where does aldosterone have it’s action
Principal cells in the late distal convulted tubule and collecting duct
What are the affects of aldosterone locally and in the blood
Makes Na/K atpase pump work harder; K+ channels in apical membrane (efflux); Na channels in apical membrane (influx)
Blood: Loose K+; Na + increases; Water increase
Where does ADH have its affect and how
Collecting duct cells that are impermeable to water. Aquaporins are placed in the cells to allow water to move through.
How does Aldosterone alter pH
Alpha interculated cells. When too acidic will give HCO3- (exchange with Cl-) to blood to form H20/CO2
Cl-goes to blood through channel
H+ leaves through transporter through apical membrane; channel exchange for Na+
What is renal replacement therapy
Blood circulated in an extracorpeal circuit its composition is modified by a mass transfer of solute and water by diffusive/convective forces accros an interfacing semipermebale membrane
Define diffusion in dialysis
Movement down concentration gradient or thermodynamic potenetial
What are the determinates for diffusion
Molecular weight (inverse) molecular charge, protien binding, volume of distribution; celluar seclusion
Define Convection in dialysis
water driven through membrane by hydrostatic pressure gradients, solutes disolved in water move through by solvent drag
What are the determinates for convection
hydrostatic pressure gradient, hydralic pressure and membrane surface area / seiving coefficent
Define adsorption
molecular attachement of a solute to a material surface. Hemoperfusion
What is the primary mechanism for Intermitent hemodialysis, CRRT, CVVHDF
IHD: Diffusion (some convection, adsorption)
CRRT: Convection (some diffusion adsoprtion)
CVVHDF: Both diffusion convection
What is dialysis disequilibrium syndrome and how to avoid
Removal of solutes results in gradient, plasma water moves from vascular to intracellular space. When solutes are removed with small volume relative to the efficiency
Avoid reduce urea <5% /hr for > 300 mg/dl and <10% for <300 mg/dl BUN
What are characteristics to use RRT for toxicity
Low molecular weight (< 1500 Da)
Small volume of distribution
Minimal protien binding
Add hemoperfusion if don’t meet.
What is peritoneal dialysis
Removal of metabolites and water by the administration of a large amount of dialysate solution into the peritoneal cavity.
What is the primary mechanisms for peritoneal dialysis
Membrane is the peritoneal membrane.
Diffusion, convection, osmosis (ultrafiltration)
Osmosis- water movement
List complications of RRT
Hemorrhage- heparization
HypoCa - citrate anticoagulation
What is the difference in aphresis and TPE
Aphresis: Blood removed and seperated into its componenets then one or more is processed/removed and returned to patient
TPE is aphresis of the plasma
What determines the success of TPE
Volume of distribution
rapiditiy substance equilibrates between body compartments
ability to remove adequate amounts
Disease process in which TPE may be used to treat
Myasthenia Gravis, IMHA, Multiple myeloma, IMpolyradiculoneuritis
Complications of TPE
plasma rxns, hypocalcemia/alkalsosis- citrate; blood loss- clot in circuti; hypotension, hypoprotienemia
