Chapter 114 Kidneys Flashcards
What % of dogs have multiple renal arteries?
And cats?
Which side more common?
13% dogs
10% cats
Left more common (makes sense, aorta on L)
How many interlobar arteries are there?
3-7
From what vessels do renal capsular arteries arise?
Most commonly phrenicoabdominal and adrenal arteries
(also ovarian)
How many nephrons does a canine kidney have?
500,000
Where in the kidney are the renal corpuscles located?
Cortex
What is the name of the cells surrounding the glomerular capsule (bowmans capsule)
Podocytes
What is the size of filtration slits between glomerular capsule podocytes?
What other feature enhances the selective nature of the capsule?
60,000 daltons
Negative charge so repels other negatively charged particles (like albumin)
What is normal urine production in dogs and cats
20 - 45 ml/kg/day
Where does L gonadal vein insert?
L renal vein
What % caridac output do the kidneys receive?
What is that in ml/min/g (of kidney tissue)
25%
4 ml/min/g (highest in cortex)
How is renal blood flow calculated?
Renal perfusion pressure / renal vascular resistance
What if GFR rate relative to renal plasma flow
20%
Briefly describe the flow of water, electrolytes and urea through the nephron
- Bowmans capsule: Ultrafiltrate of blood
- PCT: 67% of Na+ and H20 actively moved out of PCT, also Cl-, K+ and HCO3-
- Thin limbs of Henle’s loop: Maintenance of medullary hypertonicity by countercurrent exchange i.e urea)
- Thick (ascending) limb of Henle’s loop: 25% Na+, Cl-, K+ actively out (this is where frusemide works (inhibitd Na2Cl-K+ symporter).
- DCT: 4% Na actively out, PTH –> Ca2+ reabsorbtion
- Collecting duct: Final regulation of water, urea, and acid secretion (ADH –> insertion of water permeabl channels here)
What causes medullary washout?
Increased medullary blood flow (through long term ivft)
What is the osmolarity of renal medullary interstitial fluid and how does this compare to interstitial fluid elsewhere?
3 mechanisms that maintain this renal medullary osmolarity
Renal medullary osmolarity 1200-1400 mOs/L vs 300 mOs/L elsewhere
Maintained by:
- Facilitative diffusion of large molecules (urea) into interstitium
- Limited ability of water to diffuse into interstitium
- Active transport of Na, K, Cl into interstitium from thick portion of loop of Henle (most important)
What % contribution does urea make to osmolarity of renal medulla?
40-50%
What parts of nephron are impermeable to urea?
Thick loop of Henel (i.e. last part of loop, DCT, cortical collecting duct
(i.e. last 3 parts of nephron except medullary part of collecting duct, which allows urea to moce out to maintain the medullary interstitial osmolarity)
What was effect of transparenchymal mattress suture in parenchyma?
Caused necrosis, fibrosis, scarring and atrophy
What factors are associated with inceased risk of bleeding during surgery?
Azotaemia (uraemia impairs platelet adhesion + aggregation)
Hypertension
Thrombocytopaenia
What % of dogs undergoing renal biopsy had abnormal coag panel?
Cats?
40% dogs
52% cats
How is normal renal size assessed on rads in dogs?
And cats?
Dogs 2 - 2.5 x lenth of adjacent vertebra
Cats 2 - 3 x “
By what mechanism is contrast filtered by kidneys?
Passive glomerular filtration i..e not a marker of renal function