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Urology
Urinary SystemMaintains blood volumeBalance of water, electrolytespH balanceRetains key substances (glucose)Removes wastesProduces 90% of erythropoietin
Where Does Urine Come From?Cellular metabolism produces ammonia.Ammonia is converted to urea (in liver).Urea is filtered by kidneys and turned into urine.
Kidneys1 million nephrons10 % per decade lost after age 40Consists of cortex and medulla
NephronForms urineFunctional unit of kidneySurrounded by complex net of capillaries
NephronGlomerulus (surrounded by Bowmans Capsule)Proximal tubuleDescending loop of HenleAscending loop of HenleDistal tubuleCollecting duct
Formation of UrineGlomular filtrationReabsorptionSecretion
Glomular FiltrationFiltrate resembles bloodAll but large proteins are filtered outFiltration based on molecular size
Reabsorption and SecretionInvolve inter cellular transportSimple diffusionFacilitated diffusion- diffusion via molecule specific carrier speeds up the process (Insulin)Active transport- lower concentration to higher concentration (requires energy)
Water and ElectrolytesNa+ is dominant extracellular cationK+ is dominant intracellular cation
Proximal Tubule65 % of Na+ and Cl- are reabsorbedWater follows sodiumProcess occurs via diffusion and active transportH+ is also secreted
Descending Loop of HenleSimple diffusion is dominant process20 % of water has already been reabsorbed
Ascending Loop of HenleReabsorption of more electolytesVery dilute urine
GlucoseGlucose normally reabsorbed via active transport before filtrate enters proximal tubuleBgL > 180 mg/dL results in spilling of glucose
UreaMolecule is very smallIs passively reabsorbedOnly about remains in urineBUN Blood Urea Nitrogen test measures amount in bloodCreatinine- another waste is too large to be reabsorbed
Renin and BP MaintenanceEnzyme produced by kidney cellsProduces Angiotensin IAngiotensin I is converted to II by Angiotensin Concerting Enzyme (ACE)Angiotensin II is vasoconstrictor
Other Urinary StructuresUretersBladderUrethraTestesProstate Gland (surrounds bladder neck)Makes the fluid that sperm combines with
Pain AssessmentVisceral- arises from hollow organs achy, crampy.. Poorly localizedReferred pain-felt in location other than site of origin
Renal and Urologic Emergencies:
Acute Renal FailureARFSudden drop in urine output < 400 mL per day (Oliguria)Anuria no urine output
Prerenal ARFDysfunction before level of kidneyInsufficient blood supplyMost common cause of ARFOften reversibleHemorrhage, heart failure, sepsis, shock
Renal ARFInjury to small blood vessels or glomerular capillariesInjury to tubular cellsInflammation or infection
Postrenal ARFDistal to kidneyUrine backs up and shuts down kidneys
Hyperkalemia
Chronic Renal FailurePermanent loss of nephrons70% lost before problems developEnd-stage renal failure needs transplant or dialysisHypertension and Diabetes
HemodialysisShunt (fistula)- Combined vein and arteryBlood is filtered 300- 400 mL/minFistula should have a vibration or thrill
complications of dialysisHypotensionChest painDysrythmiasHyperkalemiaHemorrhageSepsisSeizuresAir embolism
http://www.esrdnet5.org/Files/Education/Meetings---Presentations/Complications_Dialysis-12-09-(1).aspx
http://www.youtube.com/watch?v=toFiGSfesZk
Fistula IssuesBleeding InfectionNarrowing fistula- may lead to thrombsis
CAPDChronic ambulatory peritoneal dialysisRisk of fluid shiftsInfectionPeritonitis
Renal Calculi
Infection
Normal Lab ValuesUrine output 0.5-1 mL/kg/hrUrine ph 5 9 (higher = UTI)Creatinine level 0.6 1.4 mg/dLBUN 8-25 mg/dL