Organs Specimen Urinary System Kidney Right Kidney Left Kidney Nephron Location - Abdominopelvic region - Situated on posterior abdominal wall, on either side of vertebral column - Occupy epigastric, hypochondriac, lumbar & umbilical regions of abdomen - Extends from upper border of 11th thoracic vertebra to 3rd lumbar vertebra - 2cm lower than left kidney - Just below diaphragm & posterior to liver - Transpyloric plane passes through upper part of hilus - Little nearer to median plane than right kidney - Below diaphragm & posterior to spleen - Transpyloric plane passes through lower part of hilus - Cortex & medulla contain about 3 million Nephrons Relations Posterior (right & left) - Diaphragm - Psoas Major - Quadratus Lumborum - Transversus Abdominis Muscles - Medial & Lateral Arcuate Ligaments - Subcostal Vessels - Subcostal Nerve - Iliohypogastric & Ilioinguinal Nerves Anterior - Right Suprarenal Gland - Liver - 2nd Part of Duodenum - Hepatic Flexure of Colon - Small Intestine Posterior - 12th Rib Anterior - Left Suprarenal Gland - Spleen - Stomach - Pancreas - Splenic Vessels - Splenic Flexure of Colon - Descending Colon - Jejunum Posterior - 11th & 12th Ribs Nerve Supply - Renal plexus • (composed of sympathetic & parasympathetic fibres) - Sympathetic Fibres • Derived from T10-L1 • Vasomotor - Parasympathetic Fibres • Derived from vagus Blood Supply/Drainage Arteries - Renal Arteries • (from abdominal aorta) *** Veins - Renal veins • (drain into vena cava) Arteries - Afferent arterioles of Glomerulus Veins - Interlobular Veins Lymphatic Drainage - Lateral aortic nodes • (drain into lumbar nodes) Specimen Bladder Male Bladder Location - Situated in anterior part of pelvic cavity, just behind pubic bone Apex - Anterior pointed part - Situated near pubic symphysis - Gives attachment to median umbilical ligament Neck - Lowest & most fixed part - Presents internal urethral orifice Female Bladder Base - Triangular - Located in fundus & posterior surface - At superolateral angles ureter enters urinary bladder Trigone - Situated at lower part of base Relations Inferolateral Surfaces - Pubis- Retropubic Pad of Fat Neck - Prostate Base - Rectovesical Pouch - Vas Deferens - Seminal Vesicle - Rectum Superior Surface - Coils of Ileum Neck - Pelvic Fascia Base - Vagina Superior Surface - Uterus *** Renal artery (& accessory renal arteries in 30% of individuals) Divides into anterior & posterior divisions (at hilus) Divide into segmental arteries (end arteries which supply vascular kidney segments) Divide into lobar arteries Divide into interlobar arteries Divide into arcuate arteries Gives interlobular arteries Give rise to afferent arterioles for glomerulus Nerve Supply - Vesical Plexus of Nerves • (Contains Sympathetic & Parasympathetic Nerves) Blood Supply/Drainage Lymphatic Drainage Arteries - Superior Vesical Arteries - Inferior Vesical Arteries (Branches of internal iliac artery) - Parasympathetic Fibres • From S2, S3, S4 Nerves - Sympathetic Fibres • From T11 – L2 Spinal Segments - Detrusor Muscles • Innervated by parasympathetic fibres during urination Veins - Superior Vesical Veins - Inferior Vesical Veins (Drained into internal iliac veins) Arteries - Vaginal Artery (Branch of Internal Iliac Artery) Veins - Vesical Veins (Drained into Internal Iliac Veins) - Internal Iliac Nodes - External Iliac Nodes Organs Specimen Urinary System Origin (Embryo) - Nephrogenic part of urogenital ridge of intermediate mesoderm - Nephrogenic cord (series of kidneys) - Pronephros (initial kidney) - Mesonephric ridge / Mesonephros (second kidney) Kidney - Metanephros (permanent kidney) - Metanephric blastema (secretory part) - Ureteric Bud (excretory part, major & minor calyces) Structure Includes: - Kidneys - Ureters - Urinary Bladder - Urethra - Bean shaped organ - 10cm L x 5cm W x 2.5cm thick - Interior consists of: Cortex - Lies between renal pyramids - Covers base of renal pyramids Medulla - Made up of pyramid shaped structures, renal pyramids (apex of each pyramid projects into the minor calyx) Renal Sinus - Space with branches of renal artery, tributaries of renal vein & renal pelvis - Contains 2-3 major calyces & 10-12 minor calyces - Has 2 poles, 2 borders, 2 surfaces, 4 coverings & 5 surfaces Function - Filter out: cellular wastes, toxins, excess water/nutrients from circulatory system - Involved in: Fluid & electrolyte balance, excretion of urine - Pair of excretory organs that remove: • Waste Products of Metabolism • Excess Water • Excess Salts • From blood & maintain its pH - Balances concentrations of body fluids & electrolytes (superior, inferior, posterior, anterior superior and anterior inferior) Poles - Upper Pole (broader, close contact with adrenal gland) - Lower Pole (pointed) Borders - Lateral Border (convex) - Medial Border (concave, presents hilum) Surfaces - Anterior Surface (irregular & convex) - Posterior Surface (flat) Coverings - Fibrous Capsule (closely covers kidney) - Perirenal Fat (layer of adipose tissue, thick at borders) - Renal Fascia (loose connective tissue) - Pararenal Fat (layer of fatty tissue, thick at posterior aspect & lower pole) Hilum - Transmits renal vein (anterior most) - Renal Artery (lies between renal vein & renal pelvis) - Renal Pelvis (posterior most) - Renal plexus of nerves - Lymphatics of kidney Clinical - Reabsorbs small molecules (amino acids, glucose, ions (Na+, Cl−, Ca2+, PO3–), peptides & water • In order to maintain blood homeostasis - Produces renin • Helps regulate blood pressure - Helps regulate RBC production • Producing erythropoietin (EPO) • Stimulant of RBC production in bone marrow - Helps control Ca2+ metabolism • By activating 1,25-hydroxycholecalciferol (an active vitamin D) - Kidney Stones - Polycystic Kidney Disease - Uterine Tract Infections (UTIs) Specimen Origin (Embryo) - Metanephric Mesoderm - Continuous lengthening of excretory tubules/nephrons (PCT, loop of Henle, DCT) - Ureteric Bud Nephron (collecting duct & tubules) - Metanephric Tissue Cap at distal end of collecting tubule forms renal vesicles which form s-shaped tubules (glomerulus) Structure - Functional unit of kidney - Has 2 parts: Renal Corpuscle - Consists of: Glomerulus (network of capillaries) Bowman’s capsule Renal Tubule - Consists of: Proximal Convoluted Tubule Loop of Henle Distal Convoluted Tubule Function - Filters blood to produce urine - Renal Corpuscle • Filters blood - Renal Tubule • Glomerular filtrate passes here Clinical - Glomerulonephritis (inflammation of glomerulus) (opens into collecting tubule which open into collecting ducts) Gross Anatomy - Empty or semi filled bladder is pyramidal in shape - Has 3 parts: apex, base & neck - 3 surfaces: 1 superior & 2 inferolateral - 4 borders: 2 lateral, 1 anterior & 1 posterior - Vesicourethral Bladder (epithelium of bladder canal) - Mesonephric Ducts (epithelium of trigone) Male Bladder Trigone - Triangular area without mucosal folds - Mucosa is firmly attached to muscular layer - Has 3 angles: Inferior Angle (Internal urethral orifice situated here) 2 Superior Angles (present openings of ureters) Histology - Wall of bladder is made up of 3 layers: mucosa, muscle layer, adventitia Mucosa - Inner most layer, has many folds that project into lumen & disappear when bladder is distended - Lined by transitional epithelium Muscle Layer - Smooth muscle fibres (detrusor muscle) running in different directions Adventitia - Outer connective tissue layer (small part has serosa instead) Uvula (Vesicae) - Elevation at inferior angle of trigone (produced by prostate) -Collects urine from kidneys - Temporary reservoir, capacity of 200-300 ml - UTIs Detrusor Muscle - Arranged in whorls & spirals - Adapted for mass contraction - Remains relaxed to allow bladder to store urine - Contracts during urination to release urine Trigone - Very sensitive to expansion - Once stretched to a certain degree, urinary bladder signals brain it needs to empty - Trigonitis • Infection of trigone - Injury of sacral nerve root S2-4 causes detrusor areflexia • Inability of detrusor muscle to contract & bladder is distended Tubes Specimen Relations Origin Course Termination Constrictions Abdominal Part Posterior - Psoas Major - Transverse Processes of Lumbar Vertebrae - Genitofemoral Nerve - External Iliac Artery Anterior (Right Ureter) Anterior (Left Ureter) - 2nd Part of Duodenum - Peritoneum - Terminal Part of Ileum - Right Colic - Left Gonadal Vessels - Left Colic Vessels - Right Ileocolic - Sigmoid Colon - Right Gonadal Vessels - Sigmoid Mesocolon - Peritoneum - Root of Mesentery Ureter Pelvic Part (Downward Course) Lateral - Obturator Internus Muscle - Superior Vesical Artery - Obturator Nerve & Vessels Posterior - Internal Iliac Vessels - Sacroiliac Joint Anterior - Ovary (Females) Pelvic Part (Forward Course) Males - Crossed Superiorly By Vas Deferens - Terminal Part Is Situated Above Seminal Vesicle Females - Runs Lateral to Cervix - Lies Above Lateral Fornix of Vagina - Crossed Superiorly by Uterine Vessels - Runs down posterior abdominal wall - Lumen of ureter is narrow at 3 regions - Crosses pelvic brim (pelvic inlet) & enters pelvic cavity - Begins at lower pole of kidney as lower continuation of renal pelvis - Junction is called Pelvi-Ureteric Junction - Runs downwards & backwards on lateral wall of pelvic cavity along greater sciatic notch - Reaches ischial spine - Runs forwards & medially reaches base of urinary bladder - Runs through wall of urinary bladder - 1st Constriction At pelvi-ureteric junction - Terminates by opening into urinary bladder at lateral angles of trigone - 2nd Constriction When ureter crosses pelvic inlet - 3rd Constriction When ureter runs in wall of urinary bladder Specimen Internal urethral sphincter (sphincter vesciae) External urethral sphincter (sphincter urethrae) Female Urethra Relations Origin Course Termination - At neck of bladder - Around internal urethral orifice - Constricts the internal urethral orifice Males - At deep perineal space - Around membranous part of urethra Females - Distally & inferiorly to bladder neck - Between vaginal orifice & clitoris - Collections of mucous glands • One on each side of upper part of urethra, Paraurethral Glands (of Skene) • Homologous with male prostate - Posterior wall of urethra • Related to anterior wall of vagina - Distal end of urethra • Marked by presence of 2 mucous glands • Lie on either side of urethra (Bartholin’s gland) • Homologous to prostate in males - Within vestibule: • External urethral orifice is located anteriorly to vaginal orifice • 2-3cm posteriorly to clitoris Constrictions - Begins at internal urethral orifice at neck of bladder - Roughly 5cm behind middle of pubic symphysis - Passes inferiorly through muscular pelvic floor - Runs downwards & forwards embedded in anterior wall of vagina - Traverses urogenital diaphragm - Opens directly into perineum, in an area between labia minora: vestibule - Ends at external urethral orifice in vestibule of vagina Specimen Relations Male Urethra Prostatic Part Membranous Part Spongy (Penile) Part - Posterior wall (floor) presents: Urethral Crest / Verumontanum • Median longitudinal ridge of mucous membrane Colliculus Seminalis • Elevation in middle part of crest on which slit-like orifice of prostatic utricle is situated • On each side of this orifice, there are openings of ejaculatory ducts Prostatic Sinuses • Two vertical grooves situated 1 on each side of crest • Each sinus presents ~20-30 openings of prostatic glands Prostatic Utricle • Blind sac • ~6mm long • Lies within prostate • Directed upwards & backwards between median & posterior lobes of prostate • Homologous with uterus of females - Situated in deep perineal space - Surrounded by sphincter urethrae (external urethral sphincter) - Bulbourethral glands (of Cowper) • Placed one on either side of membranous urethra • Numerous urethral glands also open into it - Bulbourethral ducts (of Cowper) open into spongy part of urethra • After piercing perineal membrane - Ducts of bulbourethral glands • Open in fixed part of penile urethra • ~2.5cm below perineal membrane • Except in most anterior part, numerous orifices of urethral glands (of Litre) facing forwards - Several small pit-like recesses/lacunae (of Morgagni) • Open obliquely forwards • 1 lacuna in roof of navicular fossa is largest (Lacunae magna) • Lacunae receive openings of urethral glands Origin - Extends from internal urethral orifice at neck of bladder Course - Runs through prostate, deep perineal space & penis Termination - Terminates at external urethral orifice at top of penis (glans penis) - Begins at internal urethral orifice - Passes through prostate - Terminates by continuing as membranous urethra - Begins as continuation of prostatic urethra - Runs downwards & slightly forwards through membranous urethrae - Pierces perineal membrane, about 2.5cm below - Behind pubic symphysis - Terminates by continuing as spongy urethra - Begins as continuation of membranous urethra - Fixed part of penile urethra runs forwards & upwards in bulb of penis - Bends downwards in front of lower part of pubic symphysis - Continues as free part of penile urethra in corpus spongiosum penis - Terminates at external urethral orifice situate at top of glans penis Constrictions Specimen Ureter Structure Gross Anatomy - Thick-walled muscular tube - Conveys urine from kidney to urinary bladder - ~25-30cm long - 3-4mm diameter - Upper half lies in abdomen & lower half lies in pelvis Histology - Has 3 layers: Mucous Coat - Inner most layer - Many longitudinal folds that project into lumen - Lined by transitional epithelium - Has lamina propria Muscle Coat - Has inner longitudinal & outer circular layers of smooth muscle Adventitia - Outer connective tissue layer with blood vessels Internal Urethral Sphincter (Sphincter Vesciae) - Made of smooth muscle - Part of detrusor muscle (of urinary bladder) - Primary muscle for prohibiting release of urine External Urethral Sphincter (Sphincter Urethrae) - Made of skeletal muscle - Secondary sphincter to control flow of urine through the urethra Origin (Embryo) Nerve Supply - Nerves from renal, aortic & hypogastric plexus (all are sensory) - Ureteric bud from caudal part of mesonephric duct Sympathetic Fibres - From T10-L1 Parasympathetic fibres - From S2-S4 - Involuntary - Supplied by: • Autonomic Inferior Hypogastric Plexus • Vesical Nervous Plexus (sympathetic) - Voluntary - Supplied by: Pudendal Nerve (parasympathetic) Blood Supply Upper Part - Renal Vessels - Gonadal Vessels - Colic Vessels Middle Part - Abdominal Aorta - Gonadal Vessels - Iliac Vessels Pelvic Part - Vesical Vessels - Middle Rectal Vessels - Uterine Vessels Females - Vaginal Artery - Vesical Veins Males - Inferior Vesical Artery - Inferior Vesical Vein • upper part of posterior wall Urethra - Endoderm of urogenital sinus • epithelium of urethra except in lower part of males - Visceral Mesoderm • surrounding connective and smooth muscle tissue of urethra -Ectoderm • terminal part - Ureteric stone may be impacted at any of the normal constrictions of ureter • Can cause Renal Colic • Severe pain that causes spasm of ureter - During surgery, when clamping uterine artery, ureter can be clamped accidentally - UTIs - Insertion of catheter will be involuntary - Insertion of catheter will be voluntary & painful - UTIs - Catheterisation • In cases of retention of urine, bladder is catheterised with rubber/metallic catheter - Absorbed mesonephric ducts - Membranous canal (tube) - Leads from bladder - Transports & discharges urine outside body Clinical See below See below - Urethritis • Acute urethritis is commonly cause by gonococcal infection • Gives rise to purulent discharge from urethra & frequent painful micturition Specimen Male Urethra Prostatic Part Membranous Part Spongy (Penile) Part Structure - Transports & discharges urine & seminal fluid outside body - Fibromuscular tube - 18–20 cm long - In flaccid state of penis: • S-shaped • Long axis of urethra shows two curvatures - In erect state of penis: • Distal curve is obliterated, becomes J-shaped - External Urethral Meatus is narrowest part -Has 3 parts: • Prostatic Part • Membranous Part • Surrounded by sphincter urethrae • Spongy/Penile Part • Passes through bulb & corpus spongiosum of penis - Most dilated part - Upper part lined by transitional epithelium - Lower part lined by pseudostratified epithelium - On transverse section: • Semilunar in shape • Convexity directed forwards - Shortest (1.5-2cm) - Lined by pseudostratified epithelium - Narrowest & least dilatable part of male urethra - On transverse section: • Star (stellate) shaped - Narrow with uniform diameter of ~6mm in body of penis - Most of it lined by pseudostratified epithelium - Terminal part lined by stratified squamous non-keratinised epithelium - Dilated at: • Its commencement (forms intrabulbar fossa on floor & sides) • Within glans penis (forms navicular fossa on roof & sides) - On transverse section: • Lumen is a transverse opening, except for external urethral orifice which is vertical External Urethral Orifice - Narrowest part of male urethra - Forms a sagittal slit, ~6mm long - Bound on each side by a small labium Origin (Embryo) Nerve Supply Blood Supply Clinical - Caudal part of vesicourethral canal (from bladder to opening of ejaculatory ducts) - Caudal part of vesicourethral canal (anterior wall of prostatic urethra above opening of prostatic utricle) - Definitive urogenital sinus (lower part) - Definitive urogenital sinus - Prostatic plexus: Contains mixture of: • Sympathetic • Parasympathetic • Visceral Afferent Fibres Arteries - Inferior Vesical Artery Middle Rectal Artery Veins - Inferior Vesical - Middle Rectal Veins Lymphatic Drainage - Internal Iliac Nodes - External Iliac Nodes Arteries - Deep Penile Artery (branch of internal pudental artery) - Phallic part of urogenital sinus (except distal part) Veins - Deep Penile Vein Lymphatic Drainage - Deep Inguinal - Superficial Inguinal - External Iliac Nodes - Insertion of catheter will be resisted by 3 parts (curvature) • At bend of penis (lift it up to straighten it) • External Urethral Sphincter (voluntary-painful) • Internal Urethral Sphincter (involuntary) - Hypospadias • Common anomaly in which urethra opens on under surface of penis or in perineum due to incomplete fusion of urethral folds - Epispadias • Rare • Associated with ectopia vesicae • Urethra opens on upper surface of penis, as genital tubercle develops caudal to urogenital membrane Specimen Female Urethra Structure - 4cm long - 6mm diameter - Upper part lined by transitional epithelium - Major lower part lined by stratified squamous epithelium - Conducts only urine Origin (Embryo) - Caudal part of vesicourethral canal (upper part of posterior wall) - Pelvic part of urogenital sinus (lower part) Nerve Supply - Vesical Plexus - Pudendal Nerve Blood Supply Arteries - Internal Pudendal - Vaginal - Inferior Vesical Branches of vaginal arteries Veins - Internal Pudendal Veins Lymphatic Drainage - Internal Iliac Nodes Clinical - Female urethra is easily dilatable • Catheters / Cystoscopies can be easily passed - Women are more susceptible to infections of urinary tract • Due to short length -Cystitis • Bladder Infection FEATURE EMBRYOLOGICAL ORIGIN Urogenital System Intermediate Mesoderm Urinary System Nephrogenic Part of Urogenital Ridge Genital System Gonadal Ridge of Urogenital Ridge Permanent Kidney Metanephros Nephrotomes (vestigial excretory units) Pronephros Mesonephros Intermediate Mesoderm Collecting Ducts & Tubules, Ureter, Renal Pelvis, Major & Minor Calyces Ureteric Bud Epididymis / Ductus Deferens Mesonephric Duct Uterine Tube / Uterus Paramesonephric Duct Glomeruli Metanephric Tissue Cap at distal end of collecting tubule forms renal vesicles which form S-shaped Tubules Capillaries grow into pocket at one end of the S , differentiate into Glomeruli Proximal Convoluted Tubule, Loop of Henle, Distal Convoluted Tubule Continuous lengthening of Excretory Tubules/Nephrons Nephrons Metanephric Mesoderm Median Umbilical Ligament Urachus Thick fibrous cord between Umbilicus & Apex of Urinary Bladder Ejaculatory Ducts Orifices of Mesonephric Ducts move close together to: - Enter Prostatic Urethra - In the male, become Ejaculatory Ducts Trigone Mesoderm Epithelium of Urethra (Except Very Distal Parts in Males) Endoderm of Urogenital Sinus Surrounding Connective & Smooth Muscle Tissue of Urethra Visceral Mesoderm Prostate Gland - Buds that proliferate surrounding Mesenchyme of Urethra - Formed from epithelium of Prostatic Urethra Urethral & Paraurethral Glands In females, cranial part of urethra