Renal Flashcards
Filtration: glomerulus to ______
Reabsorption: _____ to peritubular capillary
Secretion: peritubular capillary to _____
Excretion: to collecting duct, ureter
Filtration: glomerulus to prox. convoluted tubule
Reabsorption: lumen of tubule to peritubular capillary (vasa recta)
Secretion: peritubular capillary to tubule
Excretion: to collecting duct, ureter
What do the kidneys do?
Remove waste/toxins from blood Maintain proper water and electrolyte balance Maintain proper pH of blood Secrete EPO Activate vitamin D
What is reabsorbed in the proximal tubule?
Mostly amino acids, protein, and glucose (that’s why hyperglycemia damages kidneys)
Also some bicarb
What is reabsorbed in the loop of henle?
Cl, K, Na and some bicarb
What is not reabsorbed in the proximal tubule, loop of henle, distal tubule, or collecting tubule, then excreted?
Urea and creatinine
What mechanisms are involved in tubuloglomerular feedback?
Baroreceptor mech: dec pressure promotes renin release, inc pressure inhibits renin
Sympathetic nerve mech: B1 stimulates renin
Macula densa mech: inc NaCl in distal renin inhibits renin, dec load promotes renin release
Normally, all filtered glucose is reabsorbed in the proximal tubule by ____ transporter
SGLT2
Can be overwhelmed by hyperglycemia
Bicarb is not directly reabsorbed across the renal epithelium, it combines with H in the tubule to form H2CO3, which dissociates to CO2 and water. What catalyzes this reaction?
Carbonic anhydrase catalyzes this reaction.
Then it catalyzes the reverse reaction as well so that bicarb can be transported out through the basolateral membrane
How do the kidneys compensate for high/low PaCO2?
When PaCO2 is high (acidosis), kidneys excrete more H (with NH3 and HPO4) and create new HCO3 by glutamine metabolism
When PaCO2 is low (alkalosis), kidneys compensate by excreting HCO3
Na-K pump is regulated by ____
Aldosterone. The more aldosterone, the more it can pump.
Acidosis can lead to _____kalemia, what exchanger contributes to this?
HYPERkalemia
H-K exchanger contributes (as it slows, we hold on to less H, but then the K isn’t being dumped in the urine either)
Insufficiency of ADH can be secondary to ____ damage, resulting in diabetes insipidus
Pituitary damage
Large volumes of dilute urine excreted leading to severe fluid and electrolyte imbalance
What 3 factors can cause renin release?
Decreased blood flow to kidneys
Reduced serum Na
Activation of sympathetic nerves to juxtaglomerular cells
What causes natriuretic peptide to be released and what does this result in?
Atrial cells in the heart are overstretched by excessive blood volume
Inhibits angiotensin II action and results in loss of Na and water in the urine
What causes urodilatin to be released and what does this result in?
Distal and collecting tubule cells identify increased volume (similar to natriuretic peptide)
Inhibits Na and water reabsorbtion
How do osmotic diuretics work?
Increase osmolality of the filtrate causing more water to remain in the tubule, which is excreted
K wasting
How do loop diuretics work?
Blocks the Na-K-Cl pumps in the ascending loop of henle
K wasting
What do thiazide diuretics block?
Na reabsorption
K wasting
Which diuretics are K sparing?
Aldosterone-blocking agents
Casts aggregate and form in the nephron and get excreted in the urine.
WBC casts are associated with ___ infection
RBC casts indicate _____
Epithelial cell casts indicate _____
WBC casts associated with renal infection (pyelonephritis)
RBC casts indicate inflammation of glomerulus (glomerulonephritis)
Epithelial cell casts indicate sloughing of tubular cells (acute tubular necrosis)
What two factors affect creatinine level?
Rate of creatinine produced from muscle (constant in absence of muscle breakdown)
Rate of creatinine excreted by kidney, determined by GFR
Elevated BUN indicates what?
Decrease in renal function/fluid volume
Increase in catabolism and dietary protein intake
What is more accurate for determining GFR, creatinine clearance or inulin clearance?
Inulin clearance is a more accurate measurement of GFR
Azotemia vs. Uremia?
Azotemia: elevated BUN and creatinine, decreased GFR
Uremia: elevated urea in blood
Azotemia can progres to uremia