Cardio V Flashcards
What is the most metabolically active part of the nephron? Second?
Proximal convoluted tubule
Thick ascending
What is the order of the nephron? (7)
Proximal Thick descending Thin Descending Think Ascending Think ascending Distal convoluted Collecting duct
Where is most of the Na/potassium in the renal tubule reabsorbed? Is this regulated?
Proximal convoluted tubule
Not regulated
What is the primary process that is occurring in the thin descending loop of henle?
Water reabsorption passively
What is the primary process that is occurring in the thick ascending loop of henle?
Reabsorption of electrolytes, no water
What is the primary process that is occurring in the distal convoluted tubule?
Na Cl reabsorption–No K
What is the primary process that is occurring in the collecting duct?
NaCl reabsorption
Where does ADH work?
Collecting duct
What part of the tubule is regulated for K uptake?
Distal convoluted tubule
What are the processes that are occurring at the glomerulus?
Non
Where is glucose reabsorbed in the nephron?
Proximal convoluted tubule
What is the relative water permeability of the distal convoluted tubule?
Very low
What is the primary transporter at the: glomerulus?
None
What is the primary transporter at the: PCT?
Na/H exchanger
Carbonic anhydrase
What is the primary transporter at the: Straight segments of the proximal tubule
Acid and base transporters
What is the primary transporter at the: thin descending loop
aquaporins
What is the primary transporter at the: thick ascending
Na/K/Cl
What is the primary transporter at the: DCT
Na/Cl
What is the primary transporter at the: cortical collecting tubule
Na channels
K channels
Aquaporins
What is the primary transporter at the: medullary collecting duct
Aquaporins
What happens when there is an increase in [Na] of the filtrate when it gets to the distal convoluted tubule?
Increased K excretion
What is the prototypical carbonic anhydrase inhibitor?
Acetazolamide
What is carbonic anhydrase needed for in the kidney? Where is it found?
HCO3 reabsorption in the proximal convoluted tubule
What is the exchanger protein in the proximal convoluted tubule, that is responsible for the reuptake of Na? Which side of the tubular cell is this found on?
Na/H exchanger
Both lumenal and basolateral–pumps H+ from circulation all the way out to the tubule in exchange for Na
What happens to the H+ that is secreted into the lumen of the renal tubule?
Combines with HCO3- to form bicarb
What happens to the bicarbonate in the nephron lumen?
carbonic anhydrase converts it to CO2 and H2O. CO2 then goes back into the tubule cell, where it forms H2CO3 again in the cell
Inhibition of carbonic anhydrase causes a major loss of what chemical in the urine? What chemical is maintained in the tubule? What is the effect of this on the circulation?
HCO3- lost
NH4 maintained
metabolic acidosis
What happens when there is decreased HCO3 absorption by the PCT? What does this cause?
Increased solute delivery to the macula densa, increasing afferent arteriolar resistance, and decreasing renal blood flow
What is tubular glomerular feedback?
Increased solute delivery to the macula densa leads to increased afferent arteriolar resistance, and low GFR
What happens to Na/Cl when HCO3 flows out of the tubule?
Na and Cl follow
Why is it that when carbonic anhydrase is inhibited, there is an increase in K excretion?
Loss of HCO3 increases Na/Cl excretion. Higher Na in the filtrate will increase K excretion
Why are carbonic anhydrase inhibitors used in the treatment of glaucoma?
CA is present in the ciliary body, and plays a role in aqueous humor production
What is the most common indication for carbonic anhydrase inhibitors?
glaucoma
Why is carbonic anhydrase used in the treatment of acute mountain sickness?
CA is present in the choroid plexus. By decreasing CSF formation, and decreasing the pH of the CSF and brain, CA can increase ventilation and diminish symptoms of mountain sickness
Why is carbonic anhydrase used in the treatment of gout or drug clearance?
Increased excretion of uric acid in alkaline urine caused by CA inhibitors
Why is carbonic anhydrase used in the treatment of edema states?
Diuretic aspect
Chronic reduction of HCO3 stores by CA inhibitors leads to what?
Hyperchloremic metabolic acidosis
How does CA inhibitors lead to renal stones?
Increased excretion of Na leads to the build up of Ca salts
How does renal K wasting occur with CA inhibitors? How can this effect be counteracted?
Increasing the lumen negative electrical potential in the collecting tubule enhances K excretion
Administer KCl
What diseases contraindicate CA inhibitors? Why?
Cirrhosis, hyperammonemia, and hepatic encephalopathy, because NH4 levels are increased with CA inhibitor
What is the MOA of osmotic diuretics?
Osmotic agents that stay in the filtrate and cause water to be pulled into it
What are the four osmotic diuretics?
Mannitol
Glycerin
Isosorbide
Urea
What is the main site of action of osmotic diuretics?
Thin loop of henle
Why is there an increased loss of K with osmotic diuretics?
Increased distal flow in the distal tubule stimulates K secretion
How do osmotic diuretics reduce acute tubular necrosis?
maintain flow through the tubule
- Remove obstructing tubular casts
- Dilution of nephrotoxic substances
- Reduction of swelling of tubular elements
Why are osmotic diuretics used in the treatment of cerebral edema?
Alter starling’s forces to pull water out of cells
What is dialysis disequilibrium syndrome?
Too rapid of a removal of solutes from ECF by hemodialysis results in a reduction of osmolality of the ECF, causing a fluid shift into the intracellular compartment
How do osmotic diuretics help in dialysis disequilibrium syndrome?
Osmotic diuretics increase the osmolality of the extracellular fluid compartment and thereby shift water back into the extracellular compartment
How do osmotic diuretics help with acute attacks of glaucoma?
Increasing osmotic pressure of the plasma, extract water from the eye
What are the three adverse effects of osmotic diuretics?
Expand extracellular fluid volume
Hyponatremia
Hypernatremia
What pts are particularly at risk for expansion of ECF volume d/t osmotic diuretics?
heart failure
How do osmotic diuretics cause hyponatremia?
Increased extraction of water
How do osmotic diuretics cause hypernatremia?
Loss of water in excess of electrolytes
Why should pts with impaired liver function not be given urea as an osmotic diuretic?
Increases ammonia level
Why should pts with an active cranial bleed not be given mannitol or urea?
Diuretic will leak out of the intravascular compartment
Why should hyperglycemic pts not be given glycerin?
Glycerin can be metabolized and cause hyperglycemia
What is the MOA of loop diuretics?
Selectively inhibit NaCl reabsorption in the thick ascending loop of henle (NKCC inhibition)
Why are loop diuretics so efficacious?
huge absorptive capacity of NaCl in the tubules
What are the three loop diuretics?
- Furosemide
- Bumetanide
- Ethacrynic acid
What is the effect of loop diuretics on the veins?
Decreased venous pressure
Why is it that you lose Ca and Mg with loop diuretics?
Decreasing the lumen positive potential that promotes Ca/Mg reabsorption
Why are loop diuretics used for acute pulmonary edema?
Rapid increase in venous capacity and fast natriuresis relieved pressure on the heart
Why are loop diuretics used to treat chronic congestive heart failure?
Minimizes pulmonary and venous congestion
Why are loop diuretics used for nephrotic syndrome?
Loop diuretics are the only drugs that are able to draw off fluid from the kidneys
What are loop diuretics used in liver cirrhosis?
Draw of edema/ascites caused by liver failure
Why are loop diuretics used in drug overdoses?
Induce a forced diuresis for rapid renal elimination of the offending drug
What are loop diuretics used in hypercalcemia?
Will maintain Ca in the lumen of the nephron, causing loss in the urine
Why are loop diuretics used to treat hyponatremia?
they interfere with the kidney’s capacity to produce concentrated urine.
Using hypertonic saline + loop diuretics
What is THE major adverse effect of loop diuretics?
Hypokalemia
