Renal Flashcards
Which structure in kidney development functions as an interim kidney for the 1st trimester and later contributes to the male genital system?
Mesonephros
When does the metanephros appear? What two embryonic structures are a part of the metanephros?
First appears in 5th week of gestation
- Uteric bud (from caudal end of mesonephric duct)
- Metanephric mesenchyme - interacts with uteric bud
What arises from the ureteric bud?
What arises from the metanephric mesenchyme?
Which embryonic structure is the last to canalize?
Ureteric bud: gives rise to ureter, pelvises, calyces and collecting ducts
Metanephric mesenchyme: interaction with ureteric bud induces formation of glomerulus through to distal convoluted tubule
Last to canalize (most common site of obsruction) is uretopelvic junction
What congenital defect is due to abnormal interaction between the ureteric bud and metaneprhic mesenchyme?
Multicystic dysplastic kidney (bilateral form often confused for ARPKD)
Ureters pass under the ________ in females and the __________ in males
Uterine artery; Ductus deferens
Total body water is __% of body weight
ICF is __% of body weight and __ of total body water
Interstitial volume is __% of body weight and __ of extracellular fluid
Total body water is 60% of body weight
ICF is 40% of body weight and 2/3 of total body water
Interstitial volume is 15% of body weight and 3/4 of extracellular fluid
Extracellular volume is measured by ________
inulin
How is renal clearance calculated? What does it mean if clearance of a substance is < than GFR?
Cx = UxV/Px where U = urine concentration, V = urine flow rate and P = plasma concentration
If Cx < GFR then there is a net tubular reabsorption of X
How is effective renal plasma flow estimated? Why is this used?
Estimated using para-aminohippuric acid (PAH) clearance because it is both filtered and actively secreted in the proximal tubule (all PAH entering the kidney is excreted)
How is the ERPF (effective renal plasma flow) calculated? How is this corrected to represent renal blood flow?
ERPF = UPAHxV/PPAH = CPAH
RBF = RPF/(1-Hct)
What is the normal filtration fraction?
How is filtered load calculated?
What is the equation for filtration fraction?
Normal FF = 20%
Filtered load (mg/min) = GFR (mL/min) x plasma concentration
FF = GFR/RPF
How is hartnup disease inherited?
What is deficient and where?
What symptoms are present?
- Autosomal recessive
- Deficiency of neutral amino acid transporters in proximal renal tubular cells and on enterocytes
- Pellagra like symptoms (dementia, diarrhea, dermatitis)
How does ATII affect the proximal convoluted tubule? PTH?
What is used as a buffer in the PCT?
- ATII: stimulates Na+/H+ exchange leading to increased Na+, H2O, and HCO3- reabsorption
- PTH: inhibits Na+/PO43- cotransport
- NH3 acts as a buffer for secreted H+
What happens in the thin descending loop of Henle?
Passively reabsorbs H2O via medullary hypertonicity - makes urine hypertonic
What is actively reabsorbed in the thick ascending loop of henle?
What is indirectly absorbed (paracellular - between cells)?
What is this portion impermeable to?
- Na+, K+, Cl- actively reabsorbed
- Paracellular reabsorption of Mg2+ and Ca2+ through (+) lumen potential generated by K+ backleak
- Impermeable to H2O
The early distal convoluted tubule actively reabsorbs ___ and ___
How does PTH affect this part of the tubule?
- The early distal convoluted tubule actively reabsorbs Na+ and Cl-
- PTH increases Ca2+/Na+ exchange (causing Ca2+ reabsorption)
In the collecting tubule, what is the MOA of aldosterone?
Insertion of Na+ channel on luminal side (through mineralocorticoid receptor)
What defect occurs in fanconi syndrome?
Reabsorptive defect in PCT - associated with increased excretion of nearly all amino acids, glucose, HCO3-, and PO43-
What is the reabsorptive defect in Bartter syndrome?
What does this result in?
Defect in thick ascending loop of Henle - affects Na+/K+/2Cl- cotransporter
Results in hypokalemia and metabolic alkalosis with hypercalciuria
What is the reabsorptive defect in Gitelman syndrome?
What does this cause?
Reabsorptive defect of NaCl in DCT - less severe than Bartter syndrome
Leads to hypokalemia, and metabolic alkalosis but without hypercalciuria
Which autosomal dominant renal tubular defect results in increased Na+ reabsorption in distal and collecting tubules?
What does it result in?
Liddle syndrome
Results in HTN, hypokalemia, metabolic alkalosis, and decreased aldosterone
In a graph showing relative concentration along proximal tubules, what is often represented by the y-axis?
TF/P = tubular fluid/plasma
What is the meaning of TF/P > 1? TF/P < 1? TF/P = 1?
TF/P > 1: solute is reabsorbed less quickly than water
TF/P = 1: solute and water are reabsorbed at same rate
TF/P < 1: Solute is reabsorbed more quickly than water
Which ion has reabsorption at a slower rate than Na+ in early proximal tubules and then matches the rate of Na+ reabsorption more distally?
Cl-
What are the 6 functions of ATII?
- Acts at ATI receptors on vascular smooth muscle causing vasoconstriction
- Constricts efferent arteriole of glomerulus
- Increases aldosterone release from adrenal gland
- Increases ADH release from pituitary
- Increases proximal tubule Na+/H+ activity
- Stimulates hypothalamus (thirst)