Voluntary Defaecation

[E.S.Prakash]

Dr Prakash,

 

It is said that we have a partial voluntary control over defecation. I was wondering whether it’s possible to voluntary defaecate without the urges which come with an intrarectal pressure of above 18 mmHg? Simply put, can we take a dump without feeling the need to?

 

Experimentation thus far is seemingly counter-productive haha.  

 

Thanks for any help,

 

Waye Young

Year 2 Student

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[E.S.Prakash]

Waye Young: 

Interesting question; my understanding is that the primary contribution of voluntary straining with regard to defecation is on the tone of the external anal sphincter; the rise of intrabdominal pressure during straining levers the pelvic floor muscles and reduces the tension in the puborectalis sling and relaxes the external anal sphincter. However, this wouldn't result in defecation if it weren't for a mass action contraction distending the rectum and bringing about reflex relaxation of the internal anal sphincter. This underscores the importance of the mass action contractions in the colon.

ESP

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