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