lecture 1 Flashcards
what 4 things does urinary tract comprise of
kidneys, ureters, urinary bladder, urethra
urinary apparatus in sequence
kidneys - ureter - urinary bladder - urethra
where does abundant kidney blood supply come from
short direct renal arteries from abdominal aorta
what does blood pressure drive in kidneys
ultrafiltration by glomerular capillaries
what drains kidneys
renal veins into inferior vena cava (posterior abdominal wall)
left of midline is abdominal aorta, right of midline is inferior vena cava
right renal artery longer than left, passing behind IVC; left renal vein longer than right, passing in front of aorta but underneath superior mesenteric artery - aneurysm; superior to inferior: coeliac axis to forgut, midline of superior mesenteric artery to midgut, renal arteries, paired gonadal arteries from anterior surface of aorta, inferior mesenteric artery to hindgut; gonadal veins drain asymmetrically (right to renal vein to IVC, left straight to IVC)
what is the renal pelvis
the broaded superior section of ureter into which kidney tubules drain
developmental lobules
usually coallesce into one structure; cortex and medulla (renal pyramid)
why is the cortex granular-looking
random organisation
why is the medulla striated
radial arrangement of tubules and micro-vessels
what is the significance of a multilobar kidney
each lobe drains through its own papilla and minor calyx; all minor calyx drain into major calyx
structure of multilobar kidney
cortex in between lobules of medulla (renal columns of cortex)
renal artery drains into interlobular artery - becomes arcuate artery and merges with neighbour - nephron
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where do ureters run vertically down
posterior abdominal wall in vertical plane of tips of transverse processes of lumbar vertebrae
where do ureters cross pelvic brim
anterior to sacro-iliac joint and run over bifurcation of common iliac arteries
where do ureters enter bladder wall obliquely having descended anteromedially
level of ischial spine
long so complicated blood supply - from every major vessel crossed: renal arteries, gonadal arteries, common iliac, internal iliac arteries and branches, some small from abdominal aorta; ureters run down from tips then forward to enter posterior section of bladder
only lose blood supply to one part and entire ureter becomes unfuctional
how is urine transported in ureters
by peristalsis of their smooth muscle walls
3 sites of ureteric constriction
pelviureteric junction (renal pelvis and ureter), where ureter crosses pelvic brim, where ureter traverses bladder wall
what are constrictions
sites of renal colic (pain) caused by kidney stones attempting to pass, being stuck in narrowest parts of ureter - pain worse as ureter contracts
transitional mucosal endothelia; tight junctions; layers move over each other so appears multi-layered; impermeable to urine; submucosa then circular smooth muscle
commonest is pelviureteric junction as first one
structure of bladder
pelvic organ in adults (in children, abdominal); shaped like a triangular pyramid, with apex pointing anteriorly and base (fundus) posteriorly
what lines bladder
urothelium (transitional epithelium)
what is significance of 3-layered epithelium in bladder
if stretched become one layer; very slow cell turnover
what do large luminal cell membranes have
highly specialised low permeability luminal membrane
significance of large luminal cell membrane
prevents dissipation of urine-plasma gradients
what is the bladder apex attached to
median umbilical ligament; ureters enter bladder at posterior-superior angles, close ureters when enter bladder, preventing backflor; trigo of bladder - ureters and neck - flat, bladder cancers most likely to arise here
posterior attachments to bladder in women
urthera, pubovesical ligament holds urethra in place, vaginal opening in deep perineal pouch and perineal membrane (urethra passes through perineal membrane - within lies external sphincter of urethra)
posterior attachments to bladder in men
bladder separated from membranous structure by prostate; puboprostatic ligament, prostate (urether runs through prostate)
anterior superior surface of full bladder
in abdomen so can puncture anterior abdominal wall to insert catheter; when rises upwards as full, pushes visceral perineum backwards so won’t enter perineal cavity when insert catheter
what are the two urinary sphincters (internal and external)
sphincter vesicae (internal), sphincter urethrae (external)
what is sphincter vesicae made from
smooth muscle
what is sphincter urethrae made from
striated muscle
where is sphincter vesicae located
at neck of bladder
what is the reflex opening of sphincter vesicae in response to
bladder wall tension
what nerves relax, and contract, sphincter vesicae
relaxed by parasympathetic nervous system, contracted by sympathetic nervous system
where is sphincter urethrae located
in perineum
what is tone maintained by in sphincter urethrae
somatic nerves in pudenal nerve (anterior division of ventral rami of S2, S3, S4)
what is sphincter urethrae opened by
voluntary inhibition of nerves - must be learned
urethra length in female - 4cm
internal: between bladder and prostate; external: below prostate
describe reflex control of bladder
bladder fills - stretch receptors - parasympathetic nerve - bladder - bladder contracts (detrusor muscle) - internal urethral sphincter (vesicae) mechanically opens when bladder contracts; sympathetic innevration to internal sphincter closes off to prevent backflow of semen during ejaculation
describe how reflex control of bladder is mediated by voluntary control
cerebral cortex stimulates motor neuron to ensure external sphincter (urethrae) remains closed
describe what happens in bladder if stretch receptors fire so much because bladder is very full
negatively inhibits motor neurone so external sphincter opens
how is urethra different in males and females
in males, have preprostatic, prostatic (in prostrate, vertical straight), memranous (external, through urogenital diaphragm), bulbar and spongy (penile; horizontal straight then vertical straight) parts of urethra; in females, straight and short
in male urethra, what does internal urethral orifice at end of bladder contain
bladder neck, bladder outlet
2 further parts of male urethra
navicular fossa (widening), external urethral meatus (where urethra ends)
lymph drainage
urine normally sterile, but esp. in females can infect urethra (short, warm and moist environment in vagina); lymph drainage follows arteriole supply (valves so pulsation of arteries drive lymph upwards) in opposite direction - from bladder: nodes surrounding internal iliac, track up to common iliac, para-aortic nodes at gonadal arteries, inferior and superior mesenteric arteries
