RENAL Flashcards
During what week does the metanephros first appear?
5th week of gestation
What structure is the ureteric bud derived from? Name 4 structures that the ureteric bud gives rise to.
Derived from caudal end of mesonephros.
Gives rise to ureter, pelvises, calyces, and collecting ducts
Most common site of obstruction in fetus
Ureteropelvic junction
Last to canalize!
An infant is born with holoprosencephaly, short arms, and short legs. In utero, you noted little amniotic fluid. What is the most likely cause of death, and what was the original cause of this disease?
This is Potter Syndrome. Oligohydramnios –> compression of the fetus –>limb deformities, facial deformities, and pulmonary hypoplasia (cause of death).
This was the failure of the ureteric bud to form.
Cause of horseshoe kidney and major association
Kidneys failed to ascend due to entrapment by inferior mesenteric artery. Associated with Turner syndrome.
What substance makes the basement membrane of the glomerulus negatively charged?
Heparan sulfate
Describe the pathogenesis of nephrotic syndrome.
The charge barrier is lost (heparan sulfate fused with basement membrane gives it a negative charge), resulting in albuminuria, hypoproteinemia, generalized edema, and hyperlipidemia.
2 substances used to calculate GFR
Inulin
Creatinine
Equation for Effective Renal Plasma Flow
ERPF = clearance of PAH
Equation for Renal Blood Flow
RBF = RPF/(1-hct)
Equation for filtration fraction
GFR/RPF
Normal = 20%
Equation for filtered load
GFR x Plasma concentration
Equation for excretion rate
V x Urine concentration
What is the maximal serum glucose concentration at which glucose can be absorbed in the tubules?
350 mg/dL
How does constriction of the AFFerent arteriole affect GFR, RBF, and FF?
GFR and RBF both decrease.
No change in FF.
How does constriction of the EFFerent arteriole affect GFR, RBF, and FF>?
Increase GFR
Decrease RBF
Increase FF
How does dilation of the AFFerent arteriole affect GFR, RBF, and FF?
Increased GFR and RBF
No change in FF
How does dilation of the EFFerent arteriole affect GFR, RBF, and FF?
Decreased GFR
Increased RBF
Decreased FF
How does an increase in serum protein affect GFR, RBF, and FF?
Decrease GFR
NO change in RBF
Decrease in FF
How does ureter stone obstruction affect GFR, RBF, and FF?
Decrease GFR
No change in RBF
Decrease FF
How do ACE inhibitors affect GFR, RBF, and FF?
Decrease GFR
Increase RBF
DEcrease FF
How do NSAIDs affect GFR, RBF, and FF?
Decrease GFR
Decrease RBF
No change in FF
What is the role of the principle cells in the collecting duct/distal tubule?
Reabsorb H20 and Na+
Secrete K+
What is the role of the intercalated cells in the collecting duct/distal tubule?
Secrete H+ or HCO3-
Reabsorb K+
What are the 2 types of intercalated cells?
H+ secreting cells
HCO3- secreting cells
What effect does aldosterone have on the intercalated cells and principle cells of the collecting duct?
Stimulates intercalated cells to secrete acid.
Increases Na+ reabsorption and K+ secretion in principle cells.
What are the critical steps involved in excreting dilute urine?
Dilution of fluid in thick asc segment as solute is reabsorbed and water remains in the lumen (d/t impermeability of water in the thick asc limb). The absence of ADH renders the distal tubule and cortical collecting duct impermeable to water. Tubular fluid is diluted even more as solute is removed from the tubular fluid in the distal tubule and cortical collecting duct but water remains. Because of the low fluid osmolality in the collecting duct and the slight permeability of the medullary collecting duct to urea, urea enters the tubule from the medullary interstitium thereby keeping the osmolality of the medullary interstitium low.
Which segment of the renal tubule is responsible for concentrating urine?
Collecting duct
Which segment of the renal tubule is responsible for diluting urine?
Thick ascending limb
Where does water reabsorption occur in the Loop of Henle?
Thin descending limb