Urinary Function and Pathology Flashcards
What does the outer region of the kidney contain?
the glomeruli, convoluted tubules of the nephron and blood vessels
What does the inner region of the kidney contain?
renal pyramids
what drains the upper and lower halves of the kidney?
the renal pelvis that has a wide funnel shaped structure at the top of each ureter that is made of calyces
What is the lumen of each ureter lined with?
transitional epithelium
Describe transitional epithelium
it is pseudo stratified tissue with cells that are cuboid in a relaxed state and squamous in a distended state; only found in the ureter and bladder
What happens as urine collects in the renal pelvis?
pressure in the pelvis then increases causing a peristaltic contraction to initiate electrical pacemakers and force urine to the bladder
PNS stimulation increases the contractions
SNS stimulation decreases the contractions
Why are the ureters placed at an angle in the bladder wall?
this increases the pressure to compress the ureter and prevent back flow (reflux) of urine up the ureter
What are the 4 layers of the bladder?
- outer serosal layer
- smooth muscle layer (detrusor)
- submucosal layer of loose CT
- inner mucosal lining of
- transitional epithelial tissue (urothelium)
What type of tissue makes up the urothelium?
stratified epithelium that is impermeable to water and salt
what is the muscle of micturition?
the detrusor muscle
What is the internal urinary sphincter?
portion of the detrusor muscle that continues downward and makes up the urethra of females and posterior urethra of males
What is the external urinary sphincter made up of?
skeletal muscle that is under voluntary control
What is located on the posterior wall of the bladder just above the neck and is small triangular area?
the trigone
What is the significance of females having a small bladder?
It means there is less resistance to the flow of urine which is why females are more prone to incontinence than males
neural control of the bladder
excitatory input causes the bladder to empty (parasympathetic)
bladder smooth muscle relaxes via sympathetic input
Where are the reflex centers for micturition located?
in the sacral segments S1-S4 and the thoracolumbar segments
What nerve innervates the bladder neck and trigone?
the hypogastric
What signals are needed for the bladder to fill?
cortical input that is inhibitory via the hypogastic nerve to promote relaxation of the detrusor and maintain continence
What signals are needed for the bladder to empty?
the cortex gives input to remove inhibition and have stimulation of the PNS neurons for contraction of the detrusor via pelvic nerves
What is the role of cortical and subcortical centers?
they keep the micturition reflex inhibited except when it is necessary and appropriate to urinate
What does high bladder tone mean?
large pressure increase with little volume added
What does low bladder tone mean?
small pressure increase with more volume added
When does the first sensation to go pee occur?
at about 150 ml
sensation of fullness in 400-500ml range
how is the micturition reflex generated?
by stretch of the bladder wall
What is the effect of cholinergic drugs?
they increase tone and contraction by stimulating parasympathetic receptors