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Urinary Bladder - Anatomy & Physiology (view source)
Revision as of 17:14, 18 August 2008
, 17:14, 18 August 2008→Anatomy
** Intermediate body
** Intermediate body
** Caudal neck
** Caudal neck
* Its wall comprises a muscle layer covered in an epithelium.
* Its size and posistion are determined by how full it is.
* Its size and posistion are determined by how full it is.
** When empty the bladder wall is wrinkled and thicker
** When empty the bladder wall is wrinkled and thicker
===Muscles of the Bladder===
===Muscles of the Bladder===
The three muscular components of the bladder described below play a pivotal part in the [[Process of Micturition | micturition reflex.]]
The three muscular components of the bladder described below play a pivotal part in the [[Process of Micturition | micturition reflex.]]
====Detrusor Muscle====
Network of smooth muscle fibres within the bladder wall which are supplied by both parasympathetic and sympathetic nerves.
Network of smooth muscle fibres within the bladder wall which are supplied by both parasympathetic and sympathetic nerves.
=====Parasympathetic Supply - Detrusor Muscle=====
* S1-S3
* Synapse in pelvic plexus or bladder wall
* Innvervate the detrusor muscle
* Action - excitatory
* Function - empty bladder
=====Sympathetic Supply - Detrusor Muscle=====
* L1-L4
* Syanpse in caudal mesenteric ganglion - bladder wall
* Receptor - beta
* Inhibitory action
* Allows bladder filling
====Internal Urethral Sphincter====
Its a thickening of the bladder musculature which is continous with the detrusor and therefore is smooth muscle. However unlike the detrusor its innervation is purely from sympathetic fibres.
Its a thickening of the bladder musculature found at the neck of the bladder which is continous with the detrusor and is therefore smooth muscle. However unlike the detrusor its innervation is purely from sympathetic fibres.
=====External Urethral Sphincter=====
=====Sympathetic Supply - Internal Urethral Sphincter=====
* L1-L4
* Synapse in caudal mesenteric ganglion
* Receptor - alpha
* Excitatory action
* Function - retain urine through increased urethral tone
====External Urethral Sphincter====
Unlike the internal sphincter the external sphincter is composed of striated muscle fibres which are under the voluntary control of the somatic nervous system
Unlike the internal sphincter the external sphincter is composed of striated muscle fibres which are under the voluntary control of the somatic nervous system
=====Somatic Motor Supply - External Urethral Sphincter=====
* S1-S2
* Pudendal Nerve
* No synapse
* Innervates the urethral skeletal muscle - external urethral sphincter
* Function is to retain urine
==The Ligaments of the Bladder==
==The Ligaments of the Bladder==