Bladder Anatomy and Physiology Flashcards
What is the normal capacity of the bladder?
400-500mL
What ligaments hold the bladder?
- Bladder neck by
- puboprostatic ligament in male
- pubovesical ligament in female - Median umbilical ligament
What is the remnant of the allantois
obliterated urachus
What is the allantois?
In embryo, the allantois is a canal that drains the urinary bladder of the fetus and that joins and runs within the umbilical cord.
What type of epitheium is in the bladder?
Transitional epithelium
What type of muscle is the bladder made off?
Detrusor muscle
What are the layers of the bladder muscle?
Detrusor muscle
Longitudinal
Circular
Spiral
How thick is the bladder muscle?
Detrusor muscle
5mm
Weakening in which sphincter causes incontinence?
Pre-prostatic sphincter (bladder neck) males
What is the arterial blood supply to the bladder?
2 arteries:
- internal vesicle artery
- external vesicle artery
arise from:
internal iliac arteries from the anterior trunk
Venous drainage of bladder?
Rich plexus of veins that ultimately empties into the internal iliac veins
Lymphatic drainage of bladder
Lymph nodes at:
- vesicle
- internal iliac
- external iliac
- common iliac lymph nodes
What structures sense bladder filling?
Afferent parasympathetic neurons > spinal cord > pontine and micturition centres
Where does the efferent motor bladder innervation arise from?
S2-4
S2 3 4 keeps the shit of the floor
What is the main centre for micturition?
Pontine micturition centre in the dorsolateral pons
Where is the sacral micturition centre?
- Intermediolateral nucleus: PS S2-4 –> bladder
2. Onuf’s nucleus: PS S2-4 –> urethra
Which nerve is responsible for urine retention?
Hypogastric (sympathetic nerve)
Which nerve is responsible for micturition (voiding)?
Pelvic nerve (parasympathetic)
Which nerve detects stretch?
Sensory pelvic nerve (afferent)
- sends impulses to S2-S4
from stretch receptors on the detrusor muscle
Which nervous systems are involved in bladder efferent innervation?
- Parasympatheic
- Sympathetic
- Somatic
Is the pelvic nerve under voluntary of involuntary action?
involuntary
What nervous system does the pelvic nerve that causes contract belong to?
Parasympathetic
What neurotransmitter and to which receptor does the pelvic nerve act on?
S2 to S4 Pelvic nerve to detrusor muscle Involuntary Parasympathetic Released ACh Acts on M3R Causes relaxation
What effects does the hypogastric nerve have on the bladder?
Hypogastric Sympathetic - detrusor muscle: relaxation (b3R) - internal sphincter: contraction (a1R) Noradrenaline
Where does the hypogastric nerve arise from?
T10-L2
What nerve controls the external urethral sphincter?
Pudendal nerve
Where does the pudendal nerve arise from?
Onuf’s nucleus
Anterior horn
S2-S4
What nerve is blocked during labour and what does this cause?
Female pudendal nerve block
Causes relaxation of external sphincter
What is the action of the pudendal nerve?
voluntary contraction of the external urethral sphincter
What nerve is used when we’re forcibly stopping ourselves from peeing?
Pudendal nerve on external urethral sphincter
What neurotransmitter and receptor does the pudendal nerve act via?
ACh
Nicotinic receptor
In BPH what drug can be used and whats it MOA?
Tamsulosin
alpha1-R blocker in neck of the bladder
of the hypogastric nerve
Where is the sacral micturition centre located?
Spinal cord
S2-S4
Intermediolateral grey area
Where is Onuf’s nucleus located?
Spinal cord
S2-4
Anterior horn
What is the relevance of Onuf’s nucleus?
Continence
Acts via pudendal nerve nerve
- somatic voluntary contraction
What is the relevance of the sacral micturition centre
Voiding
Acts on the pelvic nerve
- parasympathetic contraction
Which spinal cord injury results in incontinence?
Sacral spinal cord injury
Which nerve(s) are stimulated during retention?
- Hypogastric T10-L2
- Relaxation of detrusor muscle b3R NA
- Contraction of internal sphincter a1R NA
- Sympathetic - Pudendal (Onuf’s nucleus)
- contraction of external sphincter NR ACh
- Somatic
Which nerve(s) are stimulated during micturition?
Pelvic (sacral micturition centre) S2-S4
How do we maintain a urine flow?
- Pelvic sensory neurons keep firing to sacral micturition centre (S2-S4) - inferomediolateral grey area
- this stimulates the pelvic parasympathetic pelvic nerve to keep firing ACh at the M3R
- This maintains contraction of the detrusor muscle and thus urination
What happens during spinal shock?
Period of reduced excitability at and below spinal cord injury
What is autonomic dysreflexia?
SCI T6 or higher
- exaggerated SNS activity
