Urinary System part 2

• Ureters

  Paired fibromuscular tubes that transport urine from the renal pelvis to the urinary bladder

  
• Ureters

  • Abdominal part
  • Pelvic part
• How does the ureter penetrates the bladder wall?


  The ureter penetrates the bladder wall obliquely
• Intramural ureter

  Part of the ureter which lies within the bladder from its point of entry in the wall to the orifice in the trigone
• How does the ureter empties into urinary bladder?

  
  

  Each ureter empties into the urinary bladder by a slit opening (urethral orifices) at the cranial margin of the neck
• Ureters in cattle

  • The ureter divides into two branches directed toward the cranial and caudal poles of the kidneys
  • The primary branches of the ureter subdivide to form 18-22 secondary branches each of which carrying a calix

  
• Lower urinary tract

  Consists of urinary bladder, caudal ureter, and urethra
• Urinary bladder

  • Apex: cranial blind end
  • Body: region situated between the neck and apex
  • Neck: funnel-shaped region between ureteric orifice and urethra

  
• Bladder trigone

  Triangular region of the internal urinary bladder formed by the two ureteric orifices and the internal urethral orifice
• Anatomical location of urinary bladder

  • In carnivores, the bladder extends into the abdominal cavity
  • In large animals, the bladder confined to the pelvic cavity

  
• When the bladder enlarges and filled with urine, it becomes pear-shaped
• As the pressure rises (create the urge to void urine), tension in the bladder wall acts to CLOSE the intramural ureter and preclude urine reflux
• Detrusor muscle

  Smooth muscle coat of the bladder apex and body, expels urine
• Smooth muscle sphincter

  Muscle coat of the bladder neck & cranial urethra (internal urethral sphincter), regulates involuntary control of urine flow from the bladder to the urethra
• External urethral sphincter

  Striated urethralis muscle entirely replaces smooth muscle in the distal third of the urethra, provides voluntary control of urine flow from the bladder to the urethra
• Blood supply of urinary bladder

  • Receives main blood supply from the caudal vesical arteries, which are branches of the prostatic (male) or vaginal (female) arteries
  • Supplemented cranially by the umbilical arteries

  
• Innervation of urinary bladder

  • Receives sympathetic and parasympathetic innervation (autonomic nervous system-motor division)
  • Sympathetic fibers arise from the hypogastric nerves
  • Parasympathetic pelvic nerves are derived from the pelvic nerves
• When the bladder is full

  There are sensory nerves conveying this information to the brain to increases parasympathetic tone and decreases sympathetic activity
• Sympathetic influence on the internal urethral sphincter

  Becomes suppressed so that the internal sphincter relaxes and opens
• Urethra

  Tubular organ that serves as an outlet for urine from the urinary bladder
• Female urethra

  • Continuous with the bladder, runs caudally on the pelvic floor ventral to the reproductive tract
  • Passes obliquely through the vaginal wall and opens with the external urethral opening ventrally at the junction between vagina and vestibule
• Male urethra


  • Consists of pelvic part (preprostatic portion and prostatic portion) and penile part
  • Preprostatic portion is short, extends from the internal opening of the urethra to the seminal hillock
  • Prostatic portion is the portion that passes through the prostate gland
• Males are at greater risk of obstructive FLUTD due to their narrower urethra
• Cats with FLUTD most often show signs of difficulty and pain when urinating, increased frequency of urination, and blood in the urine
• In cattle, the ureter is formed by the short passages that lead from renal calyx

  
• Muscular part of the bladder

  • Detrusor muscle: smooth muscle coat of the bladder apex and body, expels urine
  • Smooth muscle sphincter: muscle coat of the bladder neck & cranial urethra (internal urethral sphincter)
• Internal urethral sphincter


  Regulates involuntary control of urine flow from the bladder to the urethra

  
• Sympathetic nerves


  Directly cause relaxation and expansion of the detrusor muscle, promoting urine filling
• Parasympathetic nerves


  Control bladder contractions and the passage of urine
• Urethral sphincters


  • Internal urethral sphincter: smooth muscle continuous with the detrusor muscle, regulates involuntary control of urine flow
  • External urethral sphincter: striated urethralis muscle, provides voluntary control of urine flow

  
• Urinary or urethral incontinence is the loss of voluntary control of urination, usually observed as involuntary urine leakage
• FLUTD (feline lower urinary tract disease) is a general term used to describe conditions affecting the bladder or urethra of cats, including physical conditions and behavioral disorders resulting in inappropriate urination
• The two most common types of bladder stones in cats are struvite stones and calcium oxalate stones
• How does the ureter penetrates the bladder wall

  The ureter penetrates the bladder wall obliquely.
• How does the ureter empties into urinary bladder?

  Ureter empties into UB by a slit opening (urethral orifices) at cranial margin of neck
• Struvite stones


  The most common type of bladder stone in cats; made up of magnesium, ammonium, and phosphate; can form in cats with a high urine pH
• Calcium oxalate stones


  The second most common type of bladder stone in cats; made up of calcium and oxalate; can form in cats with a low urine pH
• Sympathetic influence on the internal urethral sphincter

  Relaxes and opens the internal urethral sphincter, allowing urine to flow
• Intramural ureter


  Part of the ureter located within the bladder wall
• Urine reflux


  Backward flow of urine from the bladder into the ureter and potentially back up into the kidney