Proximal Tubular Dysfunctions and Disorders of Water Balance - Gosmanova Flashcards Preview

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Flashcards in Proximal Tubular Dysfunctions and Disorders of Water Balance - Gosmanova Deck (32)
1

What structure does the proximal tubule have that facilitates increased absorption?

microvilli (brush border)

2

Functionally, the PT is divided into three parts. Explain

S1- initial short segment of PCT
S2 - remained PCT and cortical parse recta
S3 - medullary parse recta

3

What are the functions of the proximal tubule?

Reabsorption of filtered water, electrolytes and organic compounds
Secretion of organic compounds and drugs S2/3
Hormonal Function - final pathway in the synthesis active vitamin D

4

What percentage of glucose is reabsorbed in the pt?

100%

5

What percentage of sodium is reabsorbed in pt?

55-65

6

What are the three types of transport ?

primary active
secondary active
passive

7

What drug targets Carbonic anhydrase

acetazolamide

8

What is the function of carbonic anyhydrase

it mediates the conversion of h2c03 into h20 and c02, which can diffuse into the cell.
By inhibiting carbonic anyhydrase, you can cause mild diuresis

9

what transporters does angiotensin II work on?

it activates the H-Na transporter (bringing Na into the cell) and on the HCO3-Na co transporter, pumping both into the basolateral surface

10

Why is the PT highly susceptible to ischemia

it's depend on atp in the NKA PUMP

11

What are six potential defects in PT function?

defective solute influx
leakage back into the lumen
decreased solute flux into the blood
defective energy generation or transportation
increased backflux across tight junctions
defective transporter recycling

12

PT dysfunction can be due to what and what?

generalized: usually energy generation

genetic or acquired

13

What is hereditary renal glucosuria? and it's cause

Defect in glucose reabsorption.

Mutation in SGLT2 glucose transporter in PT that absorbs glucose.

14

What is the defect in amino acid reabsorption?and cause?

cystinuira

mutation of brush border transporter responsible for reabsorption of cystine, and ornithinem lysine and arginine

15

what is the common occurence in cystinuria?

kidney stones

16

what are the three common defects in phosphate reabsorption?

x-linked hypophosphatemia
autosomal recessive hypophosphatemic rickets
oncogenic hypophosphatemic osteomalacia

17

What is the most common inherited phosphate wasting disorder? cause

x-linked hypophosphatemia

increased levels of circulating factor FGF-23 that down-regulates activity of phosphate transporter rater than transport protein mutation itself.

18

What is commonly seen in children with x-linked hypophosphatemia?

rickets

adults have osteomalacia

19

t or f hartnup disease is a defect in neutral amino acid transporter in the pt

true

20

what is vitamine d-dependent rickets type 1?

causes by mutation of 1alpha-hydroxylase leading to hypophosphatemia and rickets

21

what are metabolic abnormalities associated with fanconis syndrome?

aminoaciduria
glucosuria
hyperchloremic metabolic acidsos
hypokalemia
uricosuria

22

What are clinical manifestations of fanconis syndrome?

polyuria polydipsia
volume depletion
cardiac arrhythmias
proteinuria
growth retardation
rickets
renal stones and nephrocalcinosis
extra renal organ involvement depending on underlying cause

23

What are inherited causes of fanconi syndrome

cystinosis

24

what are acquired causes of fanconi syndrome

multiple myeloma and tenofovir

25

an osmotic pressure above what will trigger thirst mechanisms?

295

26

What has a greater ability to stimulate adh secretion: change in Posm or decrease in blood volume?

Posm (change by 1%)

BV must decrease by 7% to stimulate ADH secretion

27

What is the mechanism of ADH action in the collecting duct?

AQP2 is the renal collecting duct water channel. It will cause a quick insertion of more aqp2 into the luminal surface. long term will increase the transcription of the aqp2 gene

28

What are two drugs that inh v2rc

conivaptan and tolvaptan

29

what is the cause of hyponatremia?

increased tbw. can have increased or decresaed Na levels as well. but water always predominates

30

what are specific causes of hyponatremia?

renal losses, gi losses, skin, all have volume depletion

normal volume status - SIADH, glucocorticoid deficiency hypothyroidism

volume overload - CHF, kidney failure, cirrhosis, nephrotic syndrome

31

what is central di

lack of adh

32

what is nephrogenic di

can't respond to adh