Renal Structure and Glomerular Filtration Flashcards
Why the renal medulla is more susceptible to ischemic damage?
Vasa recta - slow flow through it - PO2 lower than cortex (lower metabolic rate)
*also preserves the osmolar gradient of the interstitium
What happen if elevated MAP is not autoregulated?
Destruction of glomerulus - renal failure
*afferent arteriole protects against sudden ⬆️ of MAP (common in malignant HTN - crisis)
What is the consequence of renal artery stenosis? Why?
- low pressures at the afferent arterioles ▶️ vasodilation of afferent and vasoconstriction efferent ▶️ HTN
- ⬆️ renin secretion ⬆️ Ag II
What change (constriction or dilation) do you expect in efferent and afferent arteriole to increase the GFR? Why?
- constrict efferent
- dilate afferent
*both cases ⬆️ glomerular capillary pressure (hydrostatic pressure that favors filtration)
Main and greater net force of reabsorption, what site of the nephron?
⬆️ oncotic pressure at peritubular capillaries at proximal tubule
Main force for filtration (GFR)
Hydrostatic pressure of the glomerular capillary
Why in nephrogenic diabetes insipidus the treatment of looses of free water and hypernatremia is with thiazide diuretics? Common cause?
- ⬆️ peritubular oncotic pressure ▶️ ⬆️ water reabsorption in PT
- sodium loss in urine
*corrects hypernatremia
What is the only factor that affect the filtration factor? How does it affect it?
- efferent arteriole constriction
- ⬆️ FF
Stimulus to release renin
- ⬇️ flow in afferent arteriole (hemorrhage, dehydration, CHF, renal artery stenosis)
- ⬆️ SANS to JG cells
- ⬇️ luminal [NaCl] at macula densa in ultrafiltrate
Structural alteration at kidney that contraindicates ACEI and ARBs?
Bilateral renal artery stenosis
What condition associated to hyperkalemia by blockage of aldosterone may lead the use of ACEI and ARBs?
Type IV Renal Tubular Acidosis
