Renal Macromolecules Flashcards
What does the glomerular ultrafiltrate consist of?
Glucose AA Hormones vitamins Salts Water Urea
What part of the kidney receives the most blood flow?
Cortex
What does the Proximal tubule reabsorb?
100% of glucose and AA
80% of electrolytes, phosphate
60% urea
How are filtered proteins reabsorbed?
endocytosis via receptors (megalin & cubulin)
The kidney is the prime location for removal of water or lipid soluble toxins
Lipid-soluble toxins are hard to get rid of.
Liver may convert them to water soluble toxins.
Kidney is therefore prime site for removal of water-soluble toxins
When do the glucose transporters get saturated?
Approx 2x normal blood glucose
What is glucose reabsorption coupled to?
Na
What breeds of dog are predisposed to nephrotic syndrome?
Dobermann, Rottweiler
What are the clinical sigs and diagnosis of nephrotic syndrome?
Weight loss, oedema, ascites, hypoalbuminaemia
Diagnosis: Loss of protein in urine (proteinuria)
What is the salt composition of ECF and ICF?
ECF is nearly all sodium
ICF is nearly all potassium
What is Hypernatraemia and what does it induce?
Hypernatraemia is high ECF Na and induces a natriuresis to cause a net loss of Na ions
How does Na cause aldosterone release?
Hyponatraemia stimulates aldosterone and Hypernatremia inhibits aldosterone
How does aldosterone act with regard to Na?
It acts via the distal tubule (by basolateral Na, K and ATPase) and the collecting duct (by apical ENaC) to resorb Na, this increases the ECF volume and subsequently BP increases.
The concentration of Na doesn’t change markedly but this is because as the quantity of Na increases the volume of ECF also increases.
What is ENaC and what does its activation in the collecting duct result in?
Epithelial sodium channel
Number of functional ENaC channels open
Plasma membrane targeting of functional ENaC channels (longevity in the membrane)
ENaC are sensitive to which loop diuretic?
Amiloride - a powerful loop diuretic that inhibits ENaC and prevent Na+ reabsorption