Renal II Flashcards
What is the normal pH range of body fluids?
7.35-7.45
What pH values are not life sustainable?
< 6.8
> 7.8
T/F: Fluids are at greater risk for becoming too basic than too acidic.
False
Body takes in and produces more acid
How is the majority of volatile acid excreted?
Exhalation
Ex. CO2
How are nonvolatile acids excreted?
Urine
Must be neutralized with HCO3
T/F: Volatile acids are regulated in the renal system.
False
Nonvolatile
How does the kidney neutralize the acids produced by the body?
Reabsorbes all of the filtered bicarbonate and produces new bicarbonate
______ allow us to keep urine pH at 4.4, yet still excrete the necessary amount of acids.
Buffers
Bind to excess H+
What molecules does the renal system use as buffers?
- Bicarbonate
- Phosphate
- Ammonium
Which buffer is used first?
Phosphate
Of the three forms of excreted acids, which are titratable?
H+ and HPO4
NH4 is NOT titratable
T/F: Net acid excretion should remove all volatile acid from the body.
False
Nonvolatile
The kidney regulates acidity of the urine by regulating ______ reabsorption.
bicarbonate
How can the renal system decrease the body pH?
Not reabsorbing all HCO3
Produces basic urine and acidic body fluids
What will be the result of the renal system resorbing all HCO3?
No effect on body pH and the urine will have a neutral pH
How can the renal system increase the bodies pH?
Typical state of the body
Reabsorb all HCO3 and produce more
Produces acidic urine and makes body fluids basic
Why does the urine become more acidic when HCO3 is resorbed?
Reaction results in H+ being secreted
T/F: 80% of HCO3 is resorbed in the proximal tubule.
True
What produces H+ and HCO3?
Carbonic anhydrase in tubular epithelium
Which cells in the collecting duct produce H+ and HCO3?
Intercalated cells
Differentiate between mechanisms of H+ secretion in the proximal tubule and the collecting duct.
Tubules have an Na+/H+ anti porter and ducts do not
How is HCO3 reabsorbed?
Transported across basolateral membrane
T/F: There are intercalated cells that reverse the process to reabsorb H+ and secrete HCO3.
True
Activity very low
T/F: Cells in the proximal tubule can alter CA activity based on intracellular pH.
True
If the body is acidic ______ will be used as an additional buffer to increase H+ excretion.
phosphate
After HCO3 has been reabsorbed and phosphate has been depleted, the kidney will produce _______ to increase H+ excretion.
Ammonium
Why can’t ammonium enter the body?
Will convert to urea and produce H+
Where is ammonium produced?
Proximal tubules via glutamine metabolism
What are the two products of glutamine metabolism?
Ammonium: goes into tubular fluid
Bicarbonate: goes into blood
What process allows for more ammonium to be added to the urine?
Diffusion trapping between loop and collecting duct
Respiratory acidosis is related to ___ build up.
CO2
What are the renal responses to respiratory acidosis and alkalosis?
Acidosis: produce HCO3
Alkalosis: excrete HCO3
What is metabolic acidosis?
Low pH due to low HCO3
Is there a respiratory response to metabolic acidosis/alkalosis?
Acidosis: hyperventilate
Alkalosis: hypoventilate
How much of ECF calcium can be filtered at the glomerulus?
A little over half
Where is the majority of calcium?
Bone
_______ can lead to increased excitability of neural and muscle tissue (tetany).
Hypocalcemia
________ can lead to cardiac arrhythmia and disorientation (possibly death).
Hypercalcemia
T/F: A decrease in plasma pH will increase the amount of free calcium.
True
Alkalosis can lead to hypocalcemia
Where are calcium sensing receptors found?
- Parathyroid gland
- Thyroid parafollicular cells
- Proximal tubule
What are the three hormones that help regulate calcium?
- Parathyroid hormone
- Calcitriol (1,25 dihydroxyvitamin D)
- Calcitonin
PTH is released during ________ and stimulates ________ production.
hypocalcemia; calcitriol
Which hormone is released in response to hypercalcemia?
Calcitonin
Increases bone deposition
How is calcium reabsorbed in the proximal tubule?
paracellular transport (solvent drag)
How is calcium reabsorbed in the thick ascending limb?
Transcellular and paracellular (not solvent drag)
Transcellular reabsorption of Ca in the distal tubule is regulated by ____.
PTH
What is diuresis?
Excess urine output
T/F: Diuretics decrease urine output due to actions on the kidney.
False
Increase
T/F: Diuretics inhibit water reabsorption.
True
What are two reasons for taking diuretics?
- Congestive heart failure
2. Hypertension
What parts of the nephron do osmotic diuretics work on?
Water permeable segments - PT and descending loop of Henle
Where is the major site of action for CA inhibitors?
Proximal tubule
Reduce H20 reabsorption by reducing Na+ reabsorption
Where do loop diuretics act in the nephron?
TAL - inhibit Na+K+2Cl- symporter
Where do thiazides act in the nephron?
Early distal tubule - block Na+Cl- symporter
What are the two classes of K+ sparing diuretics and where do they act?
- Aldosterone antagonists
- ENAC blockers
Late distal tubule/collecting duct
How do K+ sparing diuretics work?
Inhibit Na+ reabsorption and K+ secretion
Spare K+
_______ work by acting as an ADH antagonist.
Aquaretics
T/F: Osmotic diuretics increase osmotic pressure in tubular fluid.
True
What are two examples of osmotic diuretics?
Mannitol and glucose
What is a secondary effect of osmotic diuretics?
As H2O reabsorption decreases so does Ca reabsorption via less solvent drag
How do osmotic diuretics gain access to the tubules?
Glomerular filtration
T/F: CA inhibitors will reduce amount of H+ available inside the epithelial cell.
True
CA produces H+ to be used with H+/Na+ symporter. If Na+ can not get in the epithelial cell than it can not be pushed out into the blood
What is a common CA inhibitor?
Acetazolamide
T/F: CA inhibitors gain access to the tubule via glomerular filtration.
False
Secretion
T/F: CA inhibitors have the strongest diuretic effect.
False
Relatively weak
T/F: Loop diuretics have the strongest diuretic effect.
True
What is an example of a loop diuretic?
Furosemide
Loop diuretics gain access to the tubules via _______.
secretion
T/F: When loop diuretics are used, the urine that is excreted is much more dilute than the urine entering the collecting duct.
True
What is an example of a thiazide diuretic?
Chlorothiazide
Thiazides enter the tubules via ______.
secretion
T/F: Thiazides block water reabsorption in the collecting duct.
False
Works in early distal tubule
Aldosterone antagonists (spironolactone) block aldosterone receptors in the ________ cells.
principal
T/F: Cortical nephrons are more superficial than juxtamedullary nephrons.
True
T/F: ENaC blockers (amiloride) must be in the principal cell to act.
False
Can act on apical membrane from in the tubular fluid
Tolvaptan is an example of an _________.
Aquaretic
T/F: Aquaretics eliminate water without the loss of solutes.
True
What is the diuretic braking phenomenon?
Continued use of diuretics makes them less effective via compensatory mechanisms
How is the sympathetic nervous system involved in diuretic braking?
Reduced BP from diuretics -> increased symp activity -> decrease GFR -> increase proximal tubule reabsorption and increased renin
How does the increase in renin during diuretic braking counteract the diuretic?
Increased renin -> increased angiotensin II -> increased aldosterone -> decreased Na excretion
T/F: ADH release is stimulated during diuretic braking and inhibits the excretion of water.
True
K+ excretion is a secondary effect of all but what type of diuretics?
K+ sparing diuretics
________ lead to metabolic acidosis.
CA inhibitors and K+ sparing diuretics
__________ lead to metabolic alkalosis.
Loop and thiazide diuretics
All diuretics except for ________ alter calcium excretion.
K+ sparing diuretics
Osmotic and CA inhibitors act in the _________ and ________ reabsorption of calcium in that area.
proximal tubule; reduce
Loop diuretics increase calcium excretion by altering _________ transport of Ca.
paracellular
_________ stimulate reabsorption of calcium in the distal tubule.
Thiazide diuretics
T/F: In a dialyzer, the blood and fluid move in countercurrent directions.
True
Which molecules diffuse from the blood to the dialysis fluid?
Urea, potassium, and phosphate
Which molecule diffuses into the blood from the dialysis fluid?
Bicarbonate
T/F: NaCl concentrations in dialysis fluid are similar to that in blood.
True
What is the preferred way to access blood for long-term dialysis?
AV fistula
What are some risks of accessing blood through a catheter for dialysis?
scarring, vessel narrowing and occlusion
A _______ uses an artificial vessel to join an artery and vein.
AV graft
When would you use an AV graft?
Vascular problems prevent use of a fistula
What are some long-term consequences of dialysis?
Sepsis, endocarditis, and osteomyelitis
Amyloid deposits in joints
Patients with chronic renal failure are almost always diagnosed with _______.
anemia
Kidneys stop producing erythropoietin (EPO)
Where in the kidney is EPO produced?
Interstitial fibroblasts in renal cortex
EPO production is stimulated when _____ is low.
P(O2)
Which transcription factors regulate EPO synthesis?
HIF-1 and HIF-2
Patients with anemia are often treated with __________ to stimulate erythropoiesis.
Procrit
What are the side effects of Procrit?
Flu-like symptoms, headaches, high BP and CV problems
