The Urinary System Flashcards
What are the functions of the urinary system?
- stabilisation of blood pH
- regulates fluid balance
- regulates electrolyte balance
- blood pressure control
- metabolism of toxic waste products and drugs
- stimulates RBC production
- required for absorption of calcium
Describe the epithelium of the urinary system
- ureter and upper urethra: uroepithelium capable of stretching
- distal urethra: protective stratified squamous epithelium
Describe the locations of the kidneys
- retroperitoneal
- left kidney: left hyochondrium, epigastric, left lumbar and umbilical
- right kidney: right hypochrondrium, epigastric, right lumbar and umbilical
Describe the layers that surround the kidneys from deep to superficial
- renal capsule
- perinephric fat
- renal fascia
- paranephric fat
- parietal peritoneum
- anterolateral abdominal wall muscles
Describe the structure of the kidneys
- outer cortex and inner medulla
- renal pyramids and renal columns
- renal columns: extensions of cortex around pyramids
- apex of pyramids converge on minor calyces that go to major calyces into the renal pelvis which continues as ureter
Describe the structure of the nephron
- renal corpuscle (cortex)
- proximal convoluted tubule (cortex)
- loop of Henle (medulla)
- distal convoluted tubule (cortex)
- collecting duct (medulla)
Describe Nutcracker Syndrome
- compression of left renal vein by SMA
- in males results in varicocele in left spermatic cord
What are the branches of the renal artery?
- segmental artery
- interlobar artery
- arcuate artery (anastomosis between interlobar arteries)
- interlobar artery
- afferent arterioles to glomerulus
Describe the abdominal path of the ureter
- passes anterior to psoas major and branches of lumbar plexus
- closely related to gonadal vessels and crosses common iliac artery at its bifurcation
Describe the pelvic path of the ureter
Females:
- crosses umbilical artery and obturator neurovascular vessels
- forms posterior border of ovarian fossa crossed superiorly by uterine artery near cervix
Males:
- crosses umbilical artery and obturator neurovascular vessels
- crosses the ductus deferens
Describe the anatomy of the intramural ureter
- passes into bladder obliquely creating valve flap
- pressure of urine in full bladder forces valve closed
- prevents ureteric reflux
What are the 3 ureteric constrictions?
- pelvi-ureteric junction
- ureter crossing iliac vessels at pelvic inlet
- uretic orifice as it passes through bladder wall
What innervates the ureter and where does referred pain go?
- renal, abdominal aortic and superior hypogastric plexuses
- visceral afferent fibres to T11-L2
- pain referred to loin, groin, scrotum/labia
- vagus can cause nausea/vomiting
What arteries supply the ureter?
Branches from:
- renal arteries
- gonadal arteries
- aorta
- common iliac arteries
Describe the lymphatic drainage of kidneys and ureter
- kidneys: lateral aortic lymph nodes
- ureter: lateral aortic, common and internal iliac lymph nodes
What will you find between the bladder and rectum in males?
- seminal vesicles
- retrovesical septum
Describe the clinical correlations of catheters and child birth, and the bladder
- catheters can be placed urethrally or suprapubically
- repeated childbirth can weaken pelvic floor allowing bladder drop which can affect urinary continence
Describe the anatomy of the detrusor muscle
- 3 layers of smooth muscle
- internally lined with mucosa
- involuntary muscle (PSNS)
Describe the internal features of the bladder
- trigone: area between ureteric orifices and urethral orifice
- urothelium: urine proof and allows distension
- internal urethral sphincter (male): involuntary and contracts to prevent passage of semen into bladder
What are the supportive structures of the bladder?
- fascial condensations (eg. puboprostatic/pubovesical ligaments)
What are the different parts of the male urethra?
- pre-prostatic urethra
- prostatic urethra
- membranous urethra
- spongy (penile) urethra
Describe the neurovascular and lymph drainage of the bladder and urethra
- arterial: branches of internal iliac and internal pudendal
- venous: vesical (and prostatic) plexuses converging on internal ilaic veins
- lymph: internal and external iliac nodes
Describe the innervation of the bladder and urethra
- inferior hypogastric plexus
- parasympathetics from S2-4 by pelvic splanchnic nerves:
- contracts detrusor muscle and relaxes internal urethral sphincter in males
- sympathetics from T11-L2:
- contract internal urethral sphincter in males)
- somatic motor from pudendal nerve (controls external urethral sphincter)
Describe the first stage of micturition
- storage phase
- PSNS supply to detrusor muscle switched off so bladder can relax and fill
- when volume reaches 500ml it activates stretch receptors (and pain in abdomen and perineum)
- afferents sent to S2-4
- inhibition lifted
- PSNS fibres synapse in walls of bladder
- contract detrusor muscle
Describe the second stage of micturition
- voiding
- contraction of detrusor muscle by PSNS
- relaxation of external urethral sphincter by pudendal nerve
- contraction of abdo wall
- sensation of urine in urethra maintains reflex
