44 Structure of the urinary system including bladder Flashcards
What is the kidney encapsulated and protected by?
- Perirenal/ perinephric fat
- Renal fascia (derived from extraperitoneal fascia)
- Pararenal/ paranephric fat
What does the nephron consist of?
- Renal corpuscle
- Proximal convoluted tubule
- Loop of Henlé
- Distal collecting tubule
- Collecting duct
What is the function of nephron?
- Ultrafiltration
- Reabsorption
Hilum (anterior to posterior)
- Renal vien
- Renal artery
- Renal pelvis
Kidney: blood supply,
venous,
lymphatic drainage
- Renal arteries
- from aorta at L1
- posterior to renal veins
- divide at hilum - Renal veins
- inferior vena cava - Lymph to lumbar lymph nodes
Kidney: segmental,
lobal and interlobar arteries
- Each renal artery divides into 5 segmental arteries that enter kidney at its hilum
- Lobar arteries arise form each segmental artery (1 for each renal pyramid)
- Before entering the renal substance, each lobar artery gives off 2 or 3 interlobular arteries
- Interlobular arteries run towards the cortex on each side of the pyramids
- At junction of cortex and medulla the interloper artier give off the arcuate arteries that arch over the bases of the pyramids
- Arcuate arteries give off several interlobular arteries that ascend in the cortex
- The afferent glomerular arterioles (give blood directly into the renal corpuscle) arise as branches of the interlobular arteries
Kidney: nerve supply
- Derived from T12 and L1
- Referred pain to back and lumbar region as well as loin to groin
- Afferents in vagus nerve (CN X) may cause nausea and vomiting associated with such pain
What levels are kidneys located?
- Right lower than left
- Right L1-L4
- Left T12-L3
What overlies the hilum of right kidney!
2nd (descending) part of duodenum
Ureter function
Muscular tube that transports urine from kidney to bladder
How long and wide is the ureter?
25-30 cm long
3mm wide
with narrowings
Ureter narrowings?
- Pelvi-Ureteric junction
- Crossing the pelvic brim/ inlet
- Passing through the bladder wall
Relations of ureter?
Anterior to psoas major, branches of lumbar plexus
Cross bifurcation of common iliac artery
Medial to sacroiliac joints and iliac spines
Difference between pelvic relations of the ureter in males and females?
Male: between vas/ ductus deferens and seminal vesicle
Female: posterior to ovary, inferior to uterine artery, passing cervix and lateral fornix of vagina
Relations of ureter in pelvis?
Lateral to:
- Internal iliac vessels and branches
- Lumbosacral trunk
Ureter: blood, nerve supply and lymphatic drainage?
Lymph to lumbar and iliac nodes
Good longitudinal anastomosis
Nerve supply:
- supply more at lower end of ureters
- derived segmentally: T10, T11, T12, L1, S2, S3, S4 from aortic, renal and pelvic plexuses
- referred pain: T11 to L2 from loin to groin and scrotum or labia
What is the relevance of the ureters oblique entry into the bladder?
Creating a flap valve -prevents urine in bladder from backing up & returning into ureter (ureteric reflux)
What does pressure of urine in full bladder do?
Forcing ureters to close
Walls of ureters and bladder?
Muscular
How is urine propelled down ureter? What pain does it cause of ureteric calculi?
Peristaltic waves
Colicky pain
How does bladder fill?
Relaxation of detrusor muscle
How is bladder emptied?
Contraction of detrusor muscle
Aided by raised intra-abdominal pressure
Internal urethral sphincter at proximal urethra opening
What is the epithelial lining of bladder?
Transitional epithelium or urothelium
Urine-rpoof and allows distension
Detrusor muscle nerve supply?
Mainly under control of parasympathetic nerves derived from S2, S3, S4
External urethral sphincter
Around distal urethra
Striated
Under voluntary control
Anatomically, how do men prevent semen back flow into bladder?
Preprostatic smooth muscle (involuntary) internal urethral sphincter (sympathetic) at the bladder neck that contracts during ejaculation to prevent semen backflowing into the bladder that is known as retrograde ejaculation
How does female anatomy relate to urinary continence
Bladder neck is above the pelvic floor so that the pressure of pelvic organs as well as the levator ani contribute
Female urethra
- Internal urethral sphincter (bladder neck and proximal urethra)
- External urethral sphincter (striated muscle - voluntary at distal urethra)
- 4cm long and 6mm wide
- Embedded in anterior vaginal wall
- Opens in vulva
4 parts of male urethra?
- Preprostatic at bladder neck (position of smooth muscle internal urethral sphincter)
- Prostatic
- Membranous - surrounded by striated muscle external urethral sphincter
- Spongy or penile
Arterial supply of bladder and urethra?
Internal iliac artery branches (superior and inferior vesicle, middle rectal)
Branches from arteries to adjacent structures (e.g. vaginal)
Internal pudendal
Venous drainage of bladder and urethra?
Vesical (& prostatic) plexuses converging on internal iliac veins
Internal pudendal
Lymph drainage of bladder and urethra?
Internal & external iliac nodes
From the prostate there are communications (Batson venous plexus) with the internal vertebral venous plexus that may facilitate ______ _______
Tumour spread
Nerve supply of bladder and urethra
- Somatic motor for control of striated muscle (external urethral sphincter)
- Autonomic sensory & motor for both sympathetic (male internal urethral sphincter contraction) & parasympathetic (detrusor muscle contraction)
- Somatic motor from S2, S3, S4 pudendal nerve & its branches
- Sympathetic & parasympathetic in pelvic plexus (inferior hypogastric)
What are the 3 stages of micturition?
Simultaneous relaxation/contraction
- Storage:
- Parasympathetic to detrusor “switched off” in spinal cord to allow bladder to relax & fill
- Usual volume (male) about 400ml; if reach 500ml, pain in lower abdomen & perineum - “Full” causes desire to micturate/ urinate:
- Afferents (sensory) to spinal cord, then “M” Centre in pons: stimulates preganglionic, parasympathetic neurones at S2, S3, S4 - Void:
- 1y neurons stimulate 2y neurons in bladder wall ganglia causing detrusor contraction
- Simultaneous relaxation of external urethral sphincter (striated muscle) – pudendal nerve (S2, S3, S4) & contraction of abdominal wall; sensation of urine in urethra maintains the reflex
