anatomy of the urinary tract Flashcards
what is the process of elimination of urine?
- opening in renal papillae
- drains into minor calyces
- drains into major calyces
- drains into renal pelvis
- narrows to become ureter
- transported to urinary bladder for storage
- leaves body through urethra
where do the urethra begin?
renal pelvis in kidney
what are the 3 layers of the wall of the ureter?
- Inner mucous coat (consists of transitional epithelium)
- middle muscular coat
- outer fibrous coat (or adventitia)
what transports urine along ureters?
peristaltic waves
what happens when the waves reach the urinary bladder?
urine spurts through a fold of the mucous membrane and enters the bladder
what are kidney stones composed of?
uric acid, calcium oxalate, calcium phosphate or magnesium phosphate
where do kidney stones form?
in collecting ducts and renal pelvis
what % of kidney stones pass on their own?
60%
what else can be done to eliminate kidney stones?
can be shattered by sound waves and fragments leave the urine
what is the ureterorenal reflex?
constricts renal arterioles, and decreased urine production in affected kidney
what is found at the floor of the bladder
triangular trigone containing 3 openings, 2 for ureters and 1 for urethra
what are the 4 layers of the bladder wall?
- inner mucous coat
- submucous coat
- muscular coat
- outer serous coat (serosa)
what is rugae?
folds in the wall of the bladder - only seen when bladder is empty
how much can the bladder hold?
up to 1 litre
what is the bladders capacity to extend due to?
- the wall of the bladder contains folds (rugae)
- the transitional epithelium of the inner lining stretches
- smooth muscle of the bladder wall also stretches
what does micturition involve?
contraction of detrusor muscle and relaxation of the internal urethral sphincter
what are the 6 steps of micturition reflex?
- urine filling the bladder stimulates stretch receptors
- action potential are carried to sacral segment of spinal cord
- AP via parasympathetic nerves stimulate the derisory muscle to contract
- relaxation of the internal urethral sphincter
- APs also ascend the spinal column to a micturition centre in the pons
- descending pathways communicate with the sacral region of the spinal cord and their effect can be inhibitory or stimulatory
what happens if there is a conscious decision to delay urination?
- signals are sent to inhibit micturition reflex
- stimulation of somatic motor nerve to external urethral sphincter keeps it closed
what happens if there is a conscious decision to activate urination?
- inhibition of somatic nerve to external urethral sphincter keeps it open
- signals are sent from the pons to enhance the reflex
- detrusor muscle contracts and urine is expelled
what are the two sphincters of the urethra?
internal urethral sphincter (involuntary)
external urethral sphincter (voluntary)
how long is the female urethra?
about 4cm
how long is the male urethra?
about 19.5cm long
what are the three section of the male urethra?
prostatic, membranous and spongy urethra
where does the urethra teminate in males?
external urethral orifice
