Urinalysis and Urine excretion Flashcards
What are 2 blood test that can provide info about kidney function, and what do they tell us
Blood Urea Nitrogen (BUN)
- measure of urea from AA catabolism and deanimation
- if this is up GFR is down and that means kidneys are not working properly
Plasma creatine
- measure of creatine phosphate catabolism
- normally remains steady serum=urine levels, b/c it is not changed after it enters the blood stream and urine, so if it increases kidneys are not working correctly
- can overestimate by 10-20%
- used when BUN maybe unreliable
- normal is <1.6 mg/dL
What is renal plasma clearance, and why is it important
The volume of plasma (mL) that can be completely cleared of a substance per unit time (min)
Rx dosing= if a substance has a high renal plasma clearance than a high dose is needed
What is the renal plasma clearance of glucose
0 because in normal people 100% of glucose is reabsorbed/filtered so none is cleared by the kidneys
What is inulin, what is it used for and why
Plant polysaccharide that is not modified in the body and easily passes through the filter and is excreted 100% in the urine
it is used to get a true GFR
-IV given and urine and plasma levels measured as well as urine volume
Describe the path of urine
papilla->papillary duct-> minor calyces->major calyces-> renal pelvis->ureters-> urinary bladder->urethra-> external environment
What mechanism transports urine from the ureters to the bladder
peristalsis aided by hydrostatic pressure(more urine being produced) and gravity
Are the ureter walls thick or thin
thick
What are the 3 layers of the ureter, superficial to deep, and what do they do
- Adventitia=anchors ureters, contains blood vessels, nerves and lymph vessels
- Muscalaris= outer circular, inner longitudinal smooth muscle
- Mucosa= transitional epithelium w/ goblet cells that secrete mucus to protect from acidic urine
What is the average pH of urine and how can diet causes it to change
avg=6
vegetarian diet=more alkaline
high meat diet=more acidic
True or false ureters are retroperitoneal
True
Where do the ureters enter the bladder
posteriorly (back) and inferiorly (low) at the corners of the trigone
What is the anti-reflux mechanism
When the urinary bladder fills w/ urine it pulls the bladder down which closes the entrance of the ureters to the bladder so no back flow occurs
Describe the anatomic location of the urinary bladder
-posterior to the pubic symphysis, held in place by peritoneal folds
- immediately anterior to the rectum in males
- inferior and slightly anterior to uterus in females
What are the 3 layers that make up the urinary bladder wall
- A=serosa-> covers SUPERIOR surface , part of abdominal visceral peritoneum
B=adventitia-> cover POSTERIOR and INFERIOR surfaces, it is continuous w/ the ureters
- Muscularis (Detrusor muscle)
- Mucosa (uroepithelium)
When the bladder is filling is the detrusor relaxed or constricted
relaxed
what happens when the detrusor is constricted
urine is force out of the urinary bladder and into the urethra
What about the uroepithelium allows for the bladder to expand
Transitional epithelium= allows for stretch
Ruggae= folds in the uroepithelium
What is the Trigone
smooth triangular area of the bladder floor, with ureters at the posterior corners and the internal urethra oriface at the anterior corner
Where is the internal urethral sphincter and describe its composition
Near the internal urethral orifice at the trigone
-just superior to prostate in males
-the sphincter is an extension of circular smooth muscle of the detrusor
Is the internal urethral sphincter under voluntary of involuntary control
it is controlled by the parasympathetic so it is involuntary
Where is the external urethral sphincter and describe its composition
It is skeletal muscle of the pelvic floor
In males it is just inferior to the prostate
Is the external urethral sphincter under voluntary of involuntary control
voluntary
What is the dual fxn of the male urethra
passage of urine and semen
From superficial to deep what are the 2 tissue layers of the urethra
muscalaris=superficial
mucosa=deep
Name the 3 regions of the male urethra and describe them
- Prostatic=urethral surrounded by prostate gland, the duct contains opening to transport prostatic fluids and semen
- Membranous= shortest region passing through the urogenital diaphragm external urethral sphincter is located here
- Spongy= longest region contains openings for bulbourethral (cowpers) gland and extends to the external urethral office
What does the bulbourethral (cowpers) gland produce
alkaline fluid to help neutralize acidity of the urethra
Describe the location of the female urethra
posterior to pubic symphysis, runs anterior/inferior to bladder neck to the vaginal vestibule located between the clitoris and vaginal orifice
Describe the mucosal layer of the female urethra
contains epithelium and propria lamina
transitional epithelium near the bladder and transitions to stratified/pseudostratified columnar in the middle and then finally to nonkeratinized stratified squamous cells near the urethral oriface
Describe the micturition reflex
Parasympathetic reflex that initiates urination and causes:
- contraction of bladder (detusor)
- Internal urethra to open (also under parasympathetic controle)
- sensation of needing to pee
Will not urinate until voluntary contraction of external urethra allows urine to flow
What happens to our kidneys as we age
- Kidneys shrink
- RBF and GFR decrease d/t nephron deterioration
- increased incidence of calculi, inflammation, and UTI’s
- polyuria and notaria
- urinary retention
On Avg what is the volume of urine humans produce per day
1-2 L
What color should urine be
yellow or amber that varies with hydration status
diet and drugs can effect this
Should urine have an odor
yes slight aromatic, that become more ammonia-like w/ time b/c bacteria turning urea to ammonia
What is the pH range of urine and how does diet affect it
4.6-8.0 w/ an average of 6
plant based diet=more alkali
meat heavy diet = more acidic
What is the avg specific gravity of urine
1.001-1.035, higher solutes higher specific gravity
