Urinary Flashcards
Define concentrating ability:
renal capacity to resorb water in excess of solutes in the glomerualr filtrate
concentrate glomerular filtrate
Define diluting ability:
capacity to resorb solutes in excess of water in teh gloimerular filtate
dilute glomerular filtrate
Define Isosthenuria:
USG= 1.007 to 1.013
urine osmolality = serum osmolality
Define Hyposthenuria:
USG
Define Hypersthenuria:
concentrated urine >1.013, variable species to species on appropriateness
What produces ADH?
pituitary in response to hypovolemia, hyperosmolality
Where does ADH act?
collecting tubules
aquaporins/water resorption
needs medullary hypertonicity
urea, Na, Cl
Where is aldosterone produced?
Zona Glomerulosa of adrenal gland in response to:
angiotensin 2, ACTH, K+
Acts on Distal/Convoluted Tubules
What does aldosterone do?
Leads to resorption of Na/Cl
water follows
K+ is excreted
What 3 things are required by the kidney to concentrate urine?
ADH- hyperosmolality, hypovolemia, increased angiotensin
Epithelial cells in CT that are responsive to ADH
Medullary hypertonicity- osmolality of the medullary interstitial fluid must exceed that of the tubular fluid
Define azotemia
increased non protein nitrogenous compounds in the blood
increased serum creatinine
increased serum urea nitrogen
Define uremia
clinical manifestation of renal failure
Vomiting, wt loss, anemia, oral ulcers, PU/PD
Define GFR:
GLomerular filtration rate
rate substance is cleared from plasma
What is GFR depenedent on?
blood volume
cardiac output
of functional glomeruli
vessel constriction/dilation
What are the 4 stages of Renal Disease?
Diminished renal reserve
Chronic Renal insufficiency
Chronic Renal Failure
End Stage Renal Disease
Define Chronic Renal Failure:
Loss of concentrating ability may precede azotemia
> 2/3rds loss of functional renal mass you loose concentrating ability
> 3/4 ths loss of functional mass you develop azotemia
Why do animals loose concentrating ability in CRF?
more solute presented to remaining functional nephrons
high solute results in solute diuresis
Medullary hypertonicity not maintained
tissue damage, Na/Cl transport to interstitial fluid is decreased, epithelium in distal nephron tubule less responsive to ADH
Define Acute Renal Failure
can be both reversible/non-reversible
abrupt insult that markedly reduced GFR
Toxins, ischemia, infection
T/F magnitude of azotemia is used to differentiate between CRF/ARF
FALSE
moderate-marked azotemia develops quickly in ARF, takes weeks to months in CRF
What common urine volume is observed in ARF?
oliguria or anuria is common
What makes a solute ideal for measuring GFR?
freely filtered
not secreted
not resorbed
inulin, iohexol, mannitol
CREATININE
What is Creatinine?
small nitrogen based molecule; produced by degredation of creatine, creatine-phosphate
Freely filterd, minimal secretion, species specific
most frequently used to assess renal function, most efficient indirect marker of GFR
BUT it is insensitve
What is Urea Nitrogen?
BUN, SUN, UN
pdx by liver from ammonia, hepatic urea cycle
main form of nitrogenous waste in mammals
Eliminated by kidney- freely filtered, some tubule resorption, depends on flow etc
What non renal factors can affect UN serum levels?
RMT/Horses- additional routes of secretion, diet
Carnivores- mild post-prandial increase, high protein diet
GI hemmorrhage
