Urinary system 1 Flashcards
What does AKI stand for?
acute kidney injury
What does CKD stand for?
Chronic kidney disease
What is glomerular filtration?
Solute and H2O excretion via the kidneys
What is glomerular filtration rate?
The rate fluid moves from plasma to glomerular filtrate
What determines glomerular filtration rate?
Renal plasma flow
What determines renal plasma flow?
- Blood volume
- Cardiac output
- number of functional glomeruli
- constriction and dilation of the afferent and efferent glomerular arterioles
What are four other functions of the kidney?
Production of erythropoietin
» Production of 1,25-DHCC
» Secretion of RAS (renin-angiotensin system) hormones
» Secretion of other substances such as kallikriens, prostaglandins, endothelins, and adrenomedullin
What are some solutes that are excreted by the kidney?
- Urea, Creatinine, K+, H+,
What are some solutes that are conserved by the kidney?
- Sodium, Chloride, HCO3-, Magnesium, Glucose, Water,
What occurs in the proximal tubule?
Solutes (and a bit of water) out
What occurs in the descending part of the loop of henle?
Water out,
What occurs in the ascending part of the loop of henle?
Sodium Chloride out
What occurs in the collecting duct?
Concentration of the urine
What is the overall function of the kidney?
to concentrate or dilute urine as appropriate
What is the concentrating ability of the kidneys?
The ability of the kidney to absorb filtrate H20 in excess of filtarte solutes
indicated by an increase in urine specific gravity
What is the diluting ability of the kidneys?
ability of kidneys to resorb filtrate solutes in excess of H2O
generally indicated by an increase in urine specific gravity
What is urine described as when it is not concentrated or diluted?
it is described as isosthenuric
What is azotoaemia?
increase in urea or creatinine or both
What can cause azotaemia?
- May be pre-renal e.g hypovolaemia/ dehydration
- Renal- impaired renal function, amyloidosis, toxic nephrosis, renal ischemia,
- Post Renal- obstruction of the urinary tract, bladder rupture
Where is Urea synthesised?
Urea is synthesised within the liver
What does a urea decrease generally reflect?
hepatic insufficiency or a deficiency in urea cycle enzymes
Where is creatinine produced?
Creatinine is endogenously produced by muscle at a relatively constant rate
- it is freely filtered by the kidney with minimal resportion
What are the two diagnostic tests for creatinine?
Two types of assay (1) enzymatic and (2) Picric acid reaction ->coloured complex (Jaffe’s reaction)
What is SDMA ?
An amino acid produced with protein breakdown/ catabolism
increases with a 40% reduction in renal function
increases with both primary and secondary renal disease
What is FG-23?
Fibroblast growth factor 23
* secreated by osteocytes in response to increased calcitriol
* Acts on a sodium-phosphate co-transporter in the proximal tubule to reduce reabsorption of
phosphorus (promotes excretion)
What is FG23 an indicator of?
phosphorus overload early in kidney disease
What are some changes that you see in patients with renal disease?
phosphorus increases with decreased GFR
* cattle phosphorus levels are usually not impacted
Calcium
* dogs and cats may have mild hypocalcaemia
* if diet is calcium rich then horses may have hypercalcaemia
What are the three ways you can collect urine?
- Free-Catch
- Cystocentesis
- Catheter collection
What are the negatives of each urine collection method?
- Free-Catch- prone to bacterial infection
- Cystocentesis- optimal for culture and sensitivity but may require sedation
- Catheter- anaesthesia is required to place the catheteter
What are polyuria, Oliguria and Anuria respectively?
- Polyuria- increased
- Oliguria- small volumes of urine produced
- Anuria- almost no urine produced
What pigment may be normal for rabbits?
rabbits may have red due to dietary pigment
What is a normal urine colour?
pale yellow, clear (equine and rabbits may be turbid in health)
What pigments may you see in the urine?
- Obvious Yellow/ Orange- billirubin
- yellow green- bilverdin
- red/brown/black- blood, haemoglobin, myoglobin …
What are three different ways you can do urine testing?
- USG
- dipstick
- sediment evaluation
What is the meaning of isothenuric?
- Urine is neither diluted nor concentrated
What is the meaning of Hyposthenuric
Diluted urine, may be normal but if azotaemia is present then its likely to be diabetes insipidus
