Urinary system by ismail surchi

Urinary system by ismail surchi

• 1.
  Urinary System Prepared by Dr.IsmaelI. Surchi
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  The Urinary System •Urinary System is one of the four excretory systems in our body. The other three are bowel, lungs & skin.
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  Components of UrinarySystem 2 Kidneys 2 Ureters Urinary Bladder Urethra
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  The kidneys removewaste products of metabolism, excess water and salts from blood and maintain the pH . Ureters convey urine from the kidneys to the urinary bladder. The urinary bladder is the muscular reservoir of urine. Urethra is the channel to the exterior.
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  THE URETERS • Definition •The Ureters are a pair of narrow , thick walled muscular tubes which convey urine from the kidneys to urinary bladder. • Each Ureters is about 25cm (10 inch)long • The upper half lies in the abdomen and the lower half in the pelvis. • The urine is propelled from the kidney to the urinary bladder by the peristaltic contractions of the smooth muscle of the wall of the ureter.
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  Dimensions • It measures3mm diameter, but it slightly constricted at three places. – At the pelviureteric junction – At the brim of lesser pelvis – At its passage through the bladder wall • For the purpose of description, ureter is divided into 2 parts – From the site of origin to pelvic brim- abdominal part – From pelvic brim to entry into urinary bladder- pelvic part
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  COURSE IN ABDOMINAL PART •The ureter begins as a downward continuation of a funnel shaped renal pelvis at the medial margin of the lower end of the kidney. • The ureter passes downward and slight medially on the psoas major, which separates it from the transverse processes of the lumbar vertebrae. • Enters the pelvic cavity by crossing in front of the bifurcation of the common iliac artery at the pelvic brim in front of the sacroiliac joint.
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  COURSE IN PELVIS •In the pelvis, the ureter first runs downward, backward, and laterally along the anterior margin of the greatersciatic notch. • Opposite to the ischial spine, it turns forward and medially to reach the base of the urinary bladder. • Where it enters the bladder wall obliquely.
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  Ureter- Cross Section •3 layers of tissue – Outer layer • Fibrous tissue – Middle layer • Muscle – Inner layer • Epithelium
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  Relations of RightUreter Anteriorly: •Theduodenum, the terminal part ofthe ileum, the right colic andileocolic vessels,the right testicular or ovarian vessels,andthe root of the mesentery of the smallintestine. Posteriorly: • Theright psoasmuscle, which separates it fromthe lumbar transverse processes, and the bifurcation of the right common iliac artery
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  Relations of LeftUreter Anteriorly: •Thesigmoid colon and sigmoid mesocolon, the left colic vessels,and the left testicular or ovarianvessels. • The inferior mesenteric vein lies along the medial side of the leftureter Posteriorly: • Theleft psoasmuscle, which separates it fromthe lumbar transverse processes, and the bifurcation of the left common iliac artery.
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  Blood supply ofUreter •Upperendreceives blood supply from the renal arteries, • Themiddlepart may receive branches from the abdominal aorta, the testicular or ovarian arteries, and the common iliacarteries, • In the pelviccavity, the ureters are supplied by one or more arteries from branches of the internal iliac arteries and inferior vesicalarteries.
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  Blood Supply • Ureteris supplied by branches of » Renal artery » Gonadal artery » Abdominal aorta » Common iliac artery » Internal iliac artery » Uterine artery (F) » Middle rectal artery » Vaginal artery (F) » Inferior vesical artery(M) » Superior vesical artery(M)
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  LymphaticDrainageof TheUreters Lymphatic drainageof the ureters follows apattern similar to that of the arterial supply: • Theupper part of eachureter drains to the lumbarnodes; • Themiddle part of eachureter drains to lymph nodes associated with the common iliac vessels; • Theinferior part of each ureter drains to lymphnodes associated with the external and internal iliacvessels.
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  Nerve supply
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  Urinary Bladder • Theurinary bladder is a hollow , muscular organ , which functions as the reservoir for the urine received from the kidneys and to discharge it out periodically
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  Urinary Bladder • Thebladder is the most anterior element of the pelvic viscera. • It is entirely situated in the pelviccavitywhen empty,it expands superiorly into the abdomen whenfull. • Theempty bladderis shaped likea three- sidedpyramid. • It has anapex,a base,a superior surface,and two inferolateral surfaces.
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  UrinaryBladder • Theapexof thebladderis directedtoward the top of the pubic symphysis; a structure known as the median umbilical ligament (aremnant of the embryologic urachus that contributes to the formation of the bladder) continues from it superiorly up theanterior abdominal wall to the umbilicus.
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  UrinaryBladder • Thebaseof thebladder is shaped likean inverted triangle and faces posteroinferiorly.The two ureters enter the bladderat each of the upper corners of the base, andthe urethra drains inferiorly from the lower corner of thebase. • Thesmooth triangular area betweenthe openings of theureters and urethraon theinside ofthebladder is known as thetrigone
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  UrinaryBladder • Theinferolateral surfaces ofthe bladder are cradled between the levator ani muscles of the pelvic diaphragm and the adjacent obturator internus muscles above the attachmentof the pelvicdiaphragm. • The superior surface is slightly domed when the bladder isempty. • It balloons upward asthe bladderfills.
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  Neckof bladder • Theneck of thebladder surrounds the origin of the urethra at thepoint where the two inferolateral surfaces and the baseintersect. • The neck is themost inferior part of the bladder and alsothe most 'fixed' part.
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  UrinaryBladder:Location • Posterior topubicsymphysis • In females is anterior to vagina & inferior touterus
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  UrinaryBladder:Location • Posterior topubicsymphysis • In males lies anteriorto rectum
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  • 3 layers –Outer layer • Loose connective tissue – Middle layer • Smooth muscle and elastic fibres – Inner layer • Lined with transitional epithelium Histology
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  Histology
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  Relations
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  Capacity of Bladder •Empty bladder , in the adult situated within the pelvis . When distended , it rises up to the abdominal cavity and becomes an abdomino- pelvic organ. • Capacity in an adult male 120 to 320 ml. • Filling beyond 220 ml causes micturition, emptied when filled to about 250 to 300 ml. • Filling up to 500 ml may be tolerated, but beyond this it becomes painful. • Referred pain: lower part of the anterior abdominal wall, perineum and penis(T11- L2,S2-S4).
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  Blood Supply ofUrinaryBladder • Arterial supply : Main arterial supply - Superior and inferior vesical arteries arise from the anterior trunk of internal iliac arteries. • Additional arterial supply - Obturator and inferior gluteal arteries. • In the female uterine and vaginal arteries. The inferior vesical artery in female is called vaginal artery.
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  • Venous drainage •Drained by vesical venous plexus lying on the inferolateral surfac, veins from this plexus drains into internal iliac veins. • Lymphatic drainage Mainly drain into external iliac lymph nodes, some to internal iliac lymph nodes.
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  39 • • • The urethra isa canal extending from the neck of the bladder to the exterior , at the external urethral orifice. Male: about 20 cm (8”) long Female: 3-4 cm (1.5”) long – Short length is why females have more urinary tract infections than males - ascending bacteria from stool contamination Urethra urethra Urethra
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  Female Urethra • 3to 4 cm long • External urethral orifice – between vaginal orifice and clitoris • Internal urethral sphincter – detrusor muscle thickened, smooth muscle, involuntary control • External urethral sphincter – skeletal muscle, voluntary control
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  Urethra Infemale • It travelsaslightlycurved course as itpassesinferiorly through the pelvicfloorinto the perineum • where it passes through the deep perinealpouch andperineal membrane. • beforeopening in the vestibule thatlies between the labiaminora.
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  In male • 18cm long • Internal urethral sphincter • External urethral sphincter • 3 regions – prostatic urethra • during orgasm receives semen – membranous urethra • passes through pelvic cavity – penile urethra
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  • Beginningatthe baseof the bladder and passing inferiorly through the prostate, itpasses through the deep perineal pouch and perineal membrane and immediately enters the root of thepenis. • The urethra exits the deepperineal pouch, it bends forward to course anteriorlyin the root of the penis. • Whenthe penis is flaccid,the urethra makes another bend, this time inferiorly,when passing from theroot to the body of the penis. During erection,the bend between the root and body of the penisdisappears.
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  Partsof theUrethra inmale Preprostaticpart • Thepreprostaticpartofthe urethra is about 1cmlong. • Itextendsfromthebaseofthe bladderto the prostate,and is associated with a circularcuff of smooth muscle fiber (internal urethral sphincter). Contraction of this sphincter prevents retrograde movement of semen into the bladder duringejaculation. Prostaticpart • Theprostaticpartof the urethrais3-4cmlongandis surrounded by theprostate. In this region,the lumen of the urethrais markedby a longitudinalmidlinefoldof mucosa (urethralcrest).
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  Spongy (Penile)urethra • Thespongyurethra is surrounded by erectiletissue (thecorpus spongiosum)of thepenis. • Itisenlargedtoformabulbat the base of the penis and again atthe end of the penis to form the navicular fossaTheexternalurethralorificeis the sagittalslitatthe end of thepenis.
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  Histology
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  Innervationsof UrinaryBladder • Thepelvic plexus is supplying the urinary bladder with autonomic nerves. • The sympathetic innervation is directed to the blood vessels, urethral openings, and the trigone. The last thoracic and L1,2 nerves create the necessary innervation to thebladder . • Parasympathetic innervation is derived from S2,3 and 4 nerves.These are aimed at serving the detrusor muscle. • The pelvic spinal nerves are responsible for responding to the sensory response of a full bladder , which responds to the impulses sent via the central nervous system.
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  Nerve supply • Itscontains both sympathetic and parasympathetic components. • Parasympathetic efferent fibers • S2,S3, S4 are motor to the detrusor muscle and inhibitory to the sphincter vesicae. • If these are destroyed, normal micturition is not possible.
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  Nerve supply • Sympatheticefferent fibers (T11 to L2): • - inhibitory to the detrusor • - motor to the sphincter vesicae • The pudendal nerve (S2, S3, S4) • -supplies the sphincter urethrae which is voluntary • Sensory nerves: - pain sensations, causes: - spasm of bladder wall - carried by parasympathetic nerves and partly by sympathetic nerves
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  FUNCTIONSOFNERVES Nerve On detrusor muscle On internal sphincter On external sphincter Function S ympathetic nerve R elaxation ConstrictionNot supplied Filling of urinary bladder Parasympathetic nerve Constriction R elaxation Not supplied Emptying of urinary bladder Somaticnerve Not supplied Not supplied Constriction Voluntarycontrol of micturition
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  • Micturition isalso known as the voiding phase of bladder control and it is typically a short-lasting event. itsmodulatedbyhighercenters frombirth,butitisnotuntilbetweentheageof1and2yearsthatachildisable toshowbladderawarenessand,asafirststep,toreporthavingvoidedorbeing intheprocessofvoiding.  Highercentersformicturition 1) Inhibitory centers: midbrain-cerebralcortex 2) Facilitatory centers : Pons - cerebralcortex Micturition
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  MICTURITION REFLEX . Filling ofurinarybladder Stimulation of stretchreceptor Afferent impulses pass via pelvicnerve Efferent impulses via pelvicnerve Contraction of detrusormuscle & relaxationof internal sphincter Sacral segments of spinalcord
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  MICTURITION REFLEXCONTI… Flowof urineintourethra and stimulation of stretchreceptors Afferent impulses via pelvicnerve Inhibition of pudendalnerve Relaxation of externalsphincter Voiding ofurine