lower urinary tract Flashcards
Which structures lead into renal pelvis
Minor and major calyces
What type of muscle is in the renal pelvis
Smooth muscle
How does fluid move down ureter
Peristaltic contractions
How long are the ureters
30 cm
What type of epithelium is the mucosal layer
Transitional epithelium, 3-8 cells thick
What layers of smooth muscle are there
Inner: longitudinal
Outer: circular/spiral
Extra outer layer of longitudinal
How often are peristaltic waves generated
1 to 6 per minute
What causes generation of an action potential
Dilation of renal pelvis - from pacemaker cells in hilum
What is the movement of urine along the ureter known as
Peristalsis or vermiculation
How do ureters pass into bladder
At an oblique angle to prevent backflow
What layers of the bladder are there
Detrusor outer muscle layer (longitudinal and circular muscles)
Inner mucosal layer (transitional epithelium folded into rug when bladder is empty, highly elastic)
What is the trigone
Triangular area bounded by openings of ureters and urethra entrance - acts as a funnel
Storage capacity of urine
1L
Internal urethral sphincter
Loop of smooth muscle
Convergence of detrusor muscle
Involuntary control
External urethral sphincter
Circular band of skeletal muscle where urethra passes through urogenital diaphragm
Acts as a valve with resting muscle tone
Voluntary relaxation = micturition
Micturition reflex inhibited/facilitated by…?
Inhibited by higher centres in the brain
Facilitated by cortical centres in the brain
At what rate does the bladder fill
1 mL/min
What type of micturition contractions occur
Periodic reflex contractions of short duration that occur above 200mL
Which nerves usually inhibit micturation
Hypogastric and pudendal nerves
What nerve is stimulated during bladder distension
Pelvic nerve - which stimulates the hypogastric nerve
What happens when the hypogastric nerve is stimulated
Relaxation of bladder detrusor muscle
Constriction of internal sphincter
External sphincter held closed by pudendal nerve
- known as guarding reflexes
What happens when the pelvic nerve is stimulated
Contraction of detrusor muscle
Relaxation of internal sphincter
Full bladder sensation conveyed to what
Thalamus and cerebral cortex
Neural disruption of micturition
Paraplegia (periodic but unannounced bladder emptying)
Partial spinal cord damage (frequent urination)
Crush injury of dorsal roots (overflow incontinence - atonic bladder)
Problems with micturition reflex
Stroke injury/Alzheimer’s disease/brain tumour
Bladder sphincter muscles can lose tone
Urinary retention (enlarged prostate gland)
the 3 types of urinary incontinence
Loss of sensory nerves (injury - no signals from stretch receptors)
Involuntary bladder contractions (injury)
Heightened urge incontinence (sensitive bladder - foods/caffeine)
What can Ach cause
Contraction of detrusor muscle and internal sphincter relaxation
