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Uterine Contraction - Anatomy & Physiology (view source)
Revision as of 15:22, 29 November 2010
, 15:22, 29 November 2010Text replace - "-_Anatomy_%26_Physiology" to "- Anatomy & Physiology"
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* Myometrial cells contract and shorten, but do not regain their original length upon relaxation.
* Myometrial cells contract and shorten, but do not regain their original length upon relaxation.
−* Reduces the uterine volume and causes retraction of the [[Female_Reproductive_Tract_-The_Uterus_-_Anatomy_%26_Physiology|lower uterine segment]] and the [[Female_Reproductive_Tract_-The_Cervix_-_Anatomy_%26_Physiology|cervix]] to create a '''birth canal'''.
+* Reduces the uterine volume and causes retraction of the [[Female_Reproductive_Tract_-The_Uterus_- Anatomy & Physiology|lower uterine segment]] and the [[Female_Reproductive_Tract_-The_Cervix_- Anatomy & Physiology|cervix]] to create a '''birth canal'''.
'''''Retraction Ring'''''
'''''Retraction Ring'''''
−*The [[Female_Reproductive_Tract_-The_Uterus_-_Anatomy_%26_Physiology|Uterus]] is divided into two segments:
+*The [[Female_Reproductive_Tract_-The_Uterus_- Anatomy & Physiology|Uterus]] is divided into two segments:
** Upper segment: contractile
** Upper segment: contractile
** Lower segment: passive
** Lower segment: passive
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*Two hormones directly regulate myometrial contractions:
*Two hormones directly regulate myometrial contractions:
−** '''[[Pituitary_Gland_-_Anatomy_%26_Physiology#Oxytocin|Oxytocin]]''': from the posterior pituitary gland (not the corpus luteum) lowers the excitation threshold of muscle cells to increase the likelihood of action potential firing. Oxytocin also stimulates prostaglandin release.
+** '''[[Pituitary_Gland_- Anatomy & Physiology#Oxytocin|Oxytocin]]''': from the posterior pituitary gland (not the corpus luteum) lowers the excitation threshold of muscle cells to increase the likelihood of action potential firing. Oxytocin also stimulates prostaglandin release.
*** The uterine Oxytocin receptor is a G protein coupled receptor with a Gαq subinit. Thus the signalling pathway is via a calcium second messenger. Hence prostaglandin and oxytocin are complementory in action.
*** The uterine Oxytocin receptor is a G protein coupled receptor with a Gαq subinit. Thus the signalling pathway is via a calcium second messenger. Hence prostaglandin and oxytocin are complementory in action.
** '''Prostaglandins''': Stimulate liberation of calcium from intracellular stores to cause the rise in intracellular calcium concentration required for myometrial contraction.
** '''Prostaglandins''': Stimulate liberation of calcium from intracellular stores to cause the rise in intracellular calcium concentration required for myometrial contraction.