Micturation Flashcards
About how long is the ureter
25-35 cm long
How does the ureter help move urine
Undergoes peristalsis like intestines
What enhances ureteral peristalsis
Parasympathetic; inhibited by sympathetic
What modulates ureteral peristalsis
Sensory nerves
What does blocking of ureteral flow cause
Ureteral dilation
What often precedes acute renal failure
Hydronephrosis - dilation of the renal pelvis and calyces
What is the ureterorenal reflex
Blocked ureter leads to decreased urine output
What is the first location of ureteral constriction
UPJ (ureteropelvic junction)
What are the 2-4 constrictions of the ureter
- behind testicular or ovarian A or V
- pelvic brim (over external iliac A and V)
- where the ureter transverses the bladder wall
What is the the vesicoureteral reflux
Backflow of urine into the ureter and increases the risk of pyelonephritis
What is the detrusor muscle
SM of the bladder that contracts in micturition
What is the trigone
Posterior wall of bladder where ureters enter bladder and where the bladder neck opens into the posterior urethra
What is the internal sphincter of the bladder
SM in the bladder neck that contracts during rest
Involuntary
What is the external sphincter of the bladder
Skeletal muscle located in the urogenital diaphragm
Voluntary
What does the sensory nerve fibers of the bladder run with
Pelvic splanchnic N or hypogastric plexus
Where is the sacral micturition center
S2-4
What signals bladder fullness
Aδ fibers
These are myelinated
What signals bladder pain
C fibers
These are unmyelinated
More likely in disease states
When do parasympathetics predominate in the bladder
When emptying
What is the parasympathetic n for the bladder? What does it cause?
Pelvis splanchnic N
Causes detrusor contraction and internal sphincter relaxation
What are the receptors of the pelvic splanchnic n
ACh, muscarinic M3
This is the parasymp to the baldder
When does the sympathetic response dominate the bladder
Filling
What level is the sympathetic of the bladder
L2
What is the main sympathetic n for the bladder
Hypogastric n
What is the receptor of the hypogastric N
NE
Adrenergic
α1 in the urethra and bladder neck
β2-3 in detrusor muscle
What is the somatic nerve for the bladder? What level is it at
Pudendal N
S2-4
What does the pudendal n do for the bladder
Urine retention when activated
What is the NT and receptor of the pudendal N
ACh and nicotinic
Where is the urine storage or “guarding reflex” organized
Spinal cord
Where are the voiding reflexes organized
Brain
What is responsible for controlling the sacral micturition center
Pontine micturition center or Barringtons nucleus
Where does the PMC receive input from
PAG preaqueductal gray
What receives afferent bladder signals and passes them on to other brain centers? At what level
PAG
Conscious level
What is the primary excitatory input to the PMC
PAG
Urination in adults, infant, and parapalegics
Start/Stop
Detrusor and sphincter
Adults: voluntary and in coordination
Infants: involuntary and in coordination
Parapalegic: involuntary and uncoordinated
What does activation of the hypogastric N cause
Detrusor m relaxation and internal sphincter contraction
