Exam 3: Urinary system assessment Flashcards
Key anatomical components of renal system
Kidneys Ureters Bladder Sphincters Urethra
Primary function of renal system is to
maintain homeostasis by controlling the composition and volume of extracellular fluid
___% of cardiac output circulates through the kidneys
25%q
Formation of urine requires 3 steps:
Glomerular filtration
tubular reabsorption
tubular secretion
Filtration
Pressure forces liquids and dissolved substances through anatomical filtration –> filtrate created
Glomerular filtration rate (GFR):
Amount of filtrate formed/minute
GFR is directly relates to
Renal perfusion
Low bp/low volume =
low perfusion
High bp/high volume =
Increased perfusion
Impaired circulation =
low perfusion
~125 mL/min
Urine output at least
30 mL/hr
Urine output calculation
0.5-1.5ml/kg/hr
Bladder smooth muscle is supplied by
many parasympathetic fibers
The internal urethral sphincter is also
Smooth muscle
Internal urethral sphincter is under ____ control
Parasympathetic control
The external urethral sphincter is
composed of skeletal muscle
External urethral sphincter is under ____ control
Voluntary
External urethral sphincter can be tightened to
prevent urination even when the bladder is contracting and the internal sphincter is open
When relaxed and filled, both sphincters are
Closed to keep urine from dribbling out
Motor neuron inhibits external sphincter:
Relaxes and opens
Under voluntary control, impulses from cerebral cortex override
the reflex input from stretch receptors
Adults bladder capacity
600 mL
Adult urge to urinate is at
250 mL
Why are women more at risk for UTIs
because women have a 2 inch urethra while men have an 8 in
Children bladder capacity
50-60 ml
Pregnant women experienced increased frequency of urination due to
- Increased GFR secondary to increased blood volume
- Pressure of gravid (pregnant) uterus on bladder
Older male adults experience
Prostate enlargement which causes urination frequency and retention
How does menopause impact urination
frequency, nocturne, loss bladder tone, retention, residual urine–> increase UTI
By age 80, ____ of glomeruli are not function
40% of glomeruli
Th darker the urine, the more
concentrated
I & O
Intake/output
UA
urinalysis
What is in urinalysis
Albumin creatinine ratio
urine specific gravity
Urine specific gravity range
1.010 - 1.025 WNL
Urine specific gravity measures
Concentration/density
High number of urine specific gravity =
concentration urine = heavier weight/ml.
-indiacator of hydration
Blood tests of renal function and urinary status
BUN (blood urea nitrogen)
Serum Creatinine
Serum blood urea nitrogen
BUN
Serum blood urea nitrogen (BUN) normal
10-20 mg/dl
Urea:
End-product of protein metabolism
Urea is formed in the
Liver
Urea is eliminated by
Kidneys
Serum blood urea nitrogen (BUN) reflects
Liver’s ability to make urea AND kidney’s GFR
is serum blood urea nitrogen (BUN) as reliable as creatinine lab?
NO! not as reliable
Serum blood urea nitrogen (BUN) is usually measured in conjunction with
creatinine
Key factors that influence Serum blood urea nitrogen (BUN)
Impaired LIVER function
Hydration status
Nephrotoxic drugs