Urinary Tract Anatomy 2007

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Gross Anatomy of the Urinary System

DENNIS G LUSAYA, MD, FPCSAssociate Professor

Department of SurgeryUniversity Of Santo Tomas,

Manila, Philippines

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URINARY SYSTEM• Function- formation &

elimination of urine • UPPER

– Two kidneys• Organs of excretion• Regulate body fluids’

composition, volume, and pH

• Produces erthropoietin• Produces renin

– Two ureter, • LOWER

– Urinary bladder– Urethra

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UPPER URINARY SYSTEMKIDNEYS

• Located behind the peritoneum in lumbar region

• Adrenal gland rest on top

• Encased in fibrous connective tissue overlaid w/ fat

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UPPER URINARY SYSTEMKIDNEYS (Sectional

Anatomy)• Superficial outer cortex

and inner medulla– The cortex is

composed of roughly 1.25 million nephrons

– The medulla consists of 5-11 renal pyramids(pyramids of Malpighi)

– Tips terminate as 5-11 renal papillae

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UPPER URINARY SYSTEMKIDNEYS (Sectional

Anatomy)• Collecting System

includes:– 5-11 minor calyces– 2 or 3 major calyces

(fusion of minor calyces)

– Renal pelvis (main urine collection chamber, continuous w/ ureter at UPJ)

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UPPER URINARY SYSTEMKIDNEYS (Organization

of fats and fascia)• Renal capsule/Fibrous

capsule: closely applied to its outer surface

• Perirenal fat: covers the fibrous capsule

• Renal fascia(Gerota’sfascia): condensation of areolar tissue outside the perirenal fat, encloses kidney and adrenal

• Pararenal fat:external to the renal fascia(Gerota’s)

QuickTime™ and aTIFF (Uncompressed) decompress or

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UPPER URINARY SYSTEMKIDNEYS (Vascular

Supply)• Renal Artery: branches

into five segmental arteries– Anterior segmental (4):

supply anterior segment– Posterior segmental (1):

supply the posterior segment



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UPPER URINARY SYSTEMKIDNEYS (Vascular

Supply)• Renal arteries branch

repeated – Renal artery– Segmental artery– Interlobar artery– Arcuate artery– Interlobular artery– Afferent arterioles

• Renal venules follow similar opposing pattern ending with renal veins

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UPPER URINARY SYSTEMKIDNEYS (Blood Supply)

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UPPER URINARY SYSTEM

NEPHRON

• The renal corpuscle is composed of– Bowman’s capsule

and the glomerulus• The renal tubule

consists of– Proximal convoluted

tubule (PCT)– Loop of Henle– Distal convoluted

tubule (DCT)

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NEPHRON• Production of filtrate• Reabsorption of

organic nutrients• Reabsorption of water

and ions• Secretion of waste

products into tubular fluid

• Empties tubular fluid into collecting system– Collecting ducts and

papillary ducts12


URETER • Two muscular tubes that

extend from the kidney to the post surface of the UB

• Measures approx.10 inches (25cm.)

• Renal pelvis-upper expanded end

• Begins at the Ureteropelvicjunction (UPJ)

• Descends retroperitoneally, anterior to the psoas muscle

UPJ

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URETER (Normal anatomic or functional narrowings)

• UPJ (ureteropelvicjunction)

• Iliac Vessels• UVJ (ureterovesical

junction)



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UPPER URINARY SYSTEMURETER (Normal anatomic or functional narrowings) as seen on

Retrograde ureteropyelogram

QuickTime™ and aYUV420 codec decompressorare needed to see this picture.

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URETERHistologic Structure

•Thin-walled structure•Composed of Three

Layers•Adventitia•Muscular•Mucosal

•Distensible (to a degree)

•Intramural Segment Less Distensible

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URETER (Blood Supply)

• Proximal Ureter: Renal Artery

• Mid Ureter: Gonadal(testicular or Ovarian)

• Distal Ureter: Superior/Inferior Vesical, Uterine, middle rectal, Vaginal

*Veins correspond to the relevant arteries



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Nerve Supply

• Renal • Gonadal(testicular or

Ovarian)• Hypogastric plexus

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Adrenal Gland

ADRENAL GLAND: • Retroperitoneal • Close to the upper pole

of the kidneys• Right Adrenal:pyramid

shape• Left Adrenal: half-moon

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Adrenal Gland

Arterial Blood Supply:

• Superior suprarenal artery (from Inferior Phrenic artery)

• Middle suprarenal artery (from Aorta)

• Inferior suprarenal artery (from Renal artery)



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Adrenal Gland

Arterial Blood Supply:

• Superior suprarenal artery (from Inferior Phrenic artery)

• Middle suprarenal artery (from Aorta)

• Inferior suprarenal artery (from Renal artery)



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Adrenal Gland

Venous Drainage: • Right Supreranal Vein--

IVC

• Left Suprarenal Vein--Left Renal Vein



Left Adrenal Vein

IVC

Left Renal Vein

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Adrenal Gland

ADRENAL GLAND: • Structurally and

functionally, they are two glands in one– Adrenal medulla –

nervous tissue that acts as part of the SNS

– Adrenal cortex –glandular tissue derived from embryonic mesoderm

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Adrenal Gland

ADRENAL CORTEX:• Synthesizes and releases

steroid hormones called corticosteroids

• Different corticosteroids are produced in each of the three layers (GFR)– Zona glomerulosa –

mineralocorticoids(chiefly aldosterone)

– Zona fasciculata –glucocorticoids(chiefly cortisol)

– Zona reticularis –gonadocorticoids(chiefly androgens)

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Adrenal Gland

Mineralocorticoids(ADRENAL CORTEX):

• Regulate the electrolyte concentrations of extracellular fluids

• Aldosterone – most important mineralocorticoid– Maintains Na+ balance

by reducing excretion of sodium from the body

– Stimulates reabsorption of Na+ by the kidneys

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Adrenal Gland

Glucocorticoids/Cortisol(ADRENALCORTEX):

• Help the body resist stress by:– Keeping blood sugar

levels relatively constant– Maintaining blood volume

and preventing water shift into tissue

• Cortisol provokes:– Gluconeogenesis

(formation of glucose from noncarbohydrates)

– Rises in blood glucose, fatty acids, and amino acids

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Adrenal GlandGonadocorticoids/Sex

Hormones (ADRENAL CORTEX):

• Most gonadocorticoidssecreted are androgens (male sex hormones), and the most important one is testosterone

• Androgens contribute to:– The onset of puberty– The appearance of

secondary sex characteristics

– Sex drive in females • Androgens can be converted

into estrogens after menopause

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Adrenal Gland

ADRENAL MEDULLA• Made up of chromaffin

cells that secrete epinephrine and norepinephrine

• Secretion of these hormones causes:– Blood glucose levels to

rise– Blood vessels to

constrict– The heart to beat faster– Blood to be diverted to

the brain, heart, and skeletal muscle 28

LOWER URINARY TRACT

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Lower Urinary TractBladder & Urethra

(Female)• Sacral cord• Rectum• Bladder• Pubic symphysis• Urethra• Pelvic floor

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Micturition

• Act of micturition:– Storage (filling) phase– Emptying (voiding) phase

• These require opposite functions of the bladder and urethra: …– The urethra has to relax when the bladder

contracts– and vice versa

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Urinary Bladder functionDuring emptying:

• Contractile organ actively expelling urine

During storage:• Reservoir for urineWhen empty, lies at base

of pelvis on pelvic floorExpands into abdomen

as it fillsMaximum capacity

typically 500-600 mlVoiding typically at 300

ml32

Urinary Bladder AnatomySurfaces• Posterior Surface (

fundus or base)– Supple, mobile and

highly distensible– Capable of expanding

into abdomen, depending on amount of urine stored

– Males; related to the rectovesical pouch, rectum, SV, ampulla of Vas deferens

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Urinary Bladder AnatomySurfaces• Posterior Surface (

fundus or base)– Females: anterior wall of the

vagina• Anterior surface

– Pubic symphysis and retropubic space of Retzius(both male and female)

• Superior surface– Female: Vesicouterine

pouch (peritoneal cavity) and Uterus

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Urinary Bladder AnatomySurfaces• Superior Surface ( fundus

or base)– Males:peritoneal surface

• Apex– Males & Females;

-Median umbilical ligament (Urachus)

-Medial Umbilical Ligament(2): Remnant of Umbilical

arteries-Lateral Umbilical

Ligaments:elev of inferior epigatric arteries & veins

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Urinary Bladder anatomy

Surfaces• Base of bladder not

quite so distensible– Holds orifices in

place (ureters and urethra)

BaseBladder Neck

Ureteric Orifices

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Bladder muscles

• Main smooth muscle– Layer includes

detrusor and trigone• The detrusor is the

most important muscle

• A mesh of smooth muscle bundles, collagen & elastin

• The trigone is a thin smooth muscle lining over the bladder base, with a collar around ureteric orifices

• Actual function still controversial

Detrusor

Trigone

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Urinary Bladder Anatomy

Blood SupplyArteries(branch of internal iliac artery)• Superior Vesical Arteries• Inferior Vesical ArteriesVeins• Vesical Veins drain into

internal iliac



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Urinary Bladder Anatomy

NERVE SUPPLY:Sympathetic andParasympathetic nerve fibers --inferior hypo-gastric plexus



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Urethral function

• During storage:– remains closed and sealed to prevent

leakage• During emptying:

– opens, dilates and is compliant to provide conduit for urinary stream

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Urethral anatomy - femaleAdult female urethra:– 4 cm in length, up to

about 6 mm diameter when distended

– Extends from bladder neck behind symphysis pubis

– Embedded in anterior wall of vagina

Pelvic floorAdult female urethra

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Female urethra: sphincters and pelvic floor

• Smooth muscle extends throughout length of urethra

• No well-defined sphincter at bladder neck

• Striated sphincter (rhabdosphincter, external sphincter)located along middle third of urethra

• Anatomically separate from pelvic floor muscles

• Pelvic floor muscles help keep urethra closed & support bladder

Bladder neck

Pelvic floor

Striated sphincter

Urethral Anatomy - Male

Male Urethra• Shared terminal duct of

the reproductive and urinary systems which serves as a passageway for semen and urine

• Subdivided into:• Prostatic• Membranous• Penile (spongy or

cavernous)



prostatic

membranous

penile


1.Prostatic Urethra• surrounded by the

prostate gland• Urethral crest-

ejaculatory duct

2. Membranous• courses through

urogenital diaphram• surrounded deep

transverse perinealmuscle and ext. urethral sphincter



prostatic

membranous

penile


3.Penile (Spongy or Cavernous) Urethra: surrounded by corpora spongiosum



prostatic

membranous

penileFossa navicularis

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Accessory Sex GlandsProstate Gland:

• Milky, sl. Acidic fluid• Citric acid• Acid phosphatase, • Proteolytic enzymes

• PSA• Lysoszyme• Amylase• hyaluronidase


Prostate Gland: Zonal Anatomy:

• Transition• Central • Peripheral • Anterior

fibromuscularstroma




Prostate Gland: Arterial Supply:

• Inferior VesicalArtery QuickTime™ and a

TIFF (Uncompressed) decompressorare needed to see this picture.


Prostate Gland: Venous Drainage:

• Prostatic venous plexus--Internal iliac veins----IVC

• Prostatic venous plexus--- vertebral venous plexus---cranial duralsinuses



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Male urethra - sphincters• At bladder neck,

smooth muscle cells:– Form a circular collar– Extend distally to

surround pre-prostaticportion of urethra

• Just distal to prostate• Striated sphincter

surrounds membranous urethra

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The striated sphincter

• In both sexes, the striated sphincter contains 2 different types of striated muscle fibres:

• Slow twitch fibres are able maintain sphincter contraction during the long storage phase

• Fast twitch fibres are used to increase contraction rapidly and/or voluntarily (e.g. for a cough or if leakage threatens) but fatigue quickly

• Slow twitch fibres normally predominate, but the proportions can be changed by exercise or lack of exercise

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Normal micturition

Two phase:– Storage: bladder

relaxed and urethra contracting

• Duration 3 hours

– Emptying: bladder contracting and urethra relaxed

• Duration 20 seconds

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Thank You and

Good Day

Documents

Urinary Tract Anatomy 2007