# Bladder

Bladder

- The urinary bladder is a hollow muscular organ that consists of  three principal layers: lamina propria, smooth muscle and urothelium. The lamina propria contains a rich plexus of vessels, nerves and lymphatics. The detrusor is made up of a complex haphazard arrangement of  smooth muscle, which acts as functional syncytium, and elastic connective tissue, which gives the bladder its viscoelastic properties. The urothe lium is an active layer that not only acts as a barrier to protect underlying stroma from irritant urinary toxins and bacteria but also has a role in a ff erent signalling within the bladder; defects in the urothelial lining are thought to lead to several chronic benign bladder conditions . The bladder is made up of  the bladder body (the area above the level of  the ureteric orifices), the bladder base/trigone (the area below the level of  the ureteric orifices) and the bladder neck smooth muscle. 

Nervous system Origin
Course Neurotransmitter Receptor Action on bladder Action on bladder
Hypogastric
Noradrenaline
Sympathetic T10–L2
nerve
(norepinephrine)
(thoracolumbar
cord)
Pelvic nerve Acetylcholine M3 (smooth
Parasympathetic S2–4 (sacral cord
‘spinal micturition
centre’)
Somatic S2–4 (sacral cord
Pudendal
Acetylcholine Nicotinic
‘Onuf’s nucleus’)
nerve

BLADDER

The LUT consists of  the bladder and urethra, and its two functions are urinary storage and urinary emptying. These functions depend on coordinated activity between the smooth and striated muscles of  the bladder and the outlet (consisting of  the bladder neck, urethral smooth muscle, external urethral sphincter and pelvic floor muscles), which is mediated by a complex of  neural circuits in the central and peripheral nervous systems.