Renal 1 Flashcards
Proximal tubule fluid reabsorption: which solutes increase and decrease along proximal tubule?
> Increase: PAH, creatinine, inulin, urea.
Decrease: bicarbonate, glucose, amino acids.
*Na and K are reabsorbed in concentrations somewhat equal to H2O, so there is no concentration change along PCT
What amino acid is utilized in ammoniagenesis? What is the purpose of increased ammoniagenesis in acidosis?
PCT cells metabolize glutamine to glutamate, and from this reaction NH3 and HCO3- are generated.
HCO3- is absorbed and buffers acids in the blood. NH3 combines w/ H+ in urine, and NH4+ is excreted (inc. acid excretion).
What is the pathogenesis for crescent formation in RPGN?
Damage to glomerular capillaries creates gaps in basement membrane, and macrophages and fibrin pass through into Bowman’s space. Crescents are made up of proliferated glomerular parietal cells and the migrated macrophages and fibrin.
Secreted cytokines and recruited fibroblast enhance fibrin deposition, cell proliferation, and fibrosis.
What is the innervation for filling and voiding the bladder (detrusor, IUS)?
> Filling: sympathetic activation closes IUS and inhibits detrusor contraction
Voiding: parasympathetic stimulation contracts detrusor and relaxes IUS
*Voluntary control over EUS keeps from voiding (pudendal nerve)
Stress incontinence (Etx, Sx)
> Etx: no urethral support, intraabdominal pressure greater than urethral sphincter pressure (dysfunctional urethral sphincter).
Sx: leaking w/ coughing, sneezing, laughing, lifting (inc. abdominal pressure)
Urge incontinence (Etx, Sx)
> Etx: detrusor overactivity (running water, hand washing, cold weather).
Sx: Sudden, overwhelming or frequent need to pee
Overflow incontinence (Etx, Sx)
> Etx: impaired detrusor contractility, bladder outlet obstruction (diabetic autonomic neuropathy, tumor).
Sx: constant involuntary dribbling, incomplete emptying
Overflow incontinence due to Diabetic autonomic neuropathy
[Px, presentation]
First lose autonomic Afferent innervation – inability to sense full bladder – infrequent urination.
Then Efferent fibers to bladder are lost – incomplete emptying.
>Inc. postvoid residual volume to confirm inadequate emptying
Which renal tubules have the most concentrated and least concentrated tubular fluid, both w/ and w/o ADH?
> W/o ADH: most concentrated in descending limb of Henle’s loop, and the collecting ducts are least concentrated (impermeable to H20).
W/ ADH: most concentrated urine is in collecting ducts, and thick ascending limb and DCT have most dilated fluid.
How is potassium regulated by the renal tubules (PCT, collecting ducts)?
Most K is reabsorbed in PCT and Henle’s loop – fixed rate so doesn’t have big role in regulating K excretion.
>K regulation mediated by principal and alpha-intercalated cells of late distal and cortical collecting ducts.
>Hypokalemia stimulates reabsorption via H/K-ATPase of alpha-intercalated cells, and Hyperkalemia induces principal cells to secrete K.
What is the significance of the bladder being extraperitoneal in suprapubic cystostomy?
The trocar and cannula pierce the layers of the anterior abdominal wall but not the peritoneum, thus minimizing risk of peritonitis and hemoperitoneum.
