Proximal Tubule dysfunctions Flashcards
How many structural segments is the proximal Ptoximal tubule divided into and what are they?
Three. S1- initial short segment of PCT
S2- remaining PCT and cortical parse recta
S3- medullary parse recta.
The parse recta is the straight segment of the PT and has cortical and medullary segments.
True
Three main functions of PT
Reabsorb water, electrolytes, and organic compounds
Secretion of organic compounds including some drugs
Hormonal function (vit D synthesis
What are the 6 potential defects in PT function?
- Defective solute influx
- Leakage back into the lumen
- Decreased solute flux into the blood
- Defective energy genereation or transportation
- Increased backflux across tight junctions
- defective transporter recycling
Two types of PT dysfunction
Generalized or genetic and aquired
What is the gene defect in hereditary renal glucosuria
SGLT2 glucose transporter
What is cystinuria?
A defect in amino acid reabsorption caused by a mutation in brush border transporters
What is the most common inherited phosphate wasting disease?
X-linked Hypophosphatemia
FGF-23?
In X-linked hypophosphatemia, excess FGF-23 downregulates activity of phosphate transporter.
What are the characteristics of x-linked hypophosphatemia?
urinary phosphate wasting, low levels of serum phosphorus, Clinically presents as rickets in children
What the hell is hartnup disease?
Defect in neutral amino acid transporter
What are the possible mechanisms of fanconi’s syndrome?
defective binding of Na with transport proteins,
defective insertion of carriers into brush border, leaky membrane or tight junctions, abnormal NaKATPase, impaired mitochondrial energy generation.
What is fanconi’s syndrome?
Just a synonym for generalized PT dysfunction
Most common cause of Fanconi syndrome in children?
Cystinosis
What is the mechanism of cystinosis
Mutation in the transporter that transports cysteine out of lysosomes. Intra lysosomal accumulation of cysteine leads to crystalization and damage of cells.
