Why can you pee without pooing, but you can't poo without peeing?

通过我们的身体废物是由circular muscles called sphincters. The external sphinctersareunder our control.The sphincter around the urethrais smaller than the one around the anus, so when you decide to urinate you can relax it without relaxing the whole pelvic floor. This means you can pass urine without needing to pass stool at the same time.

When you do pass stool however, the relaxation of the stronger anal sphincter also decreases tension in the weaker urinary sphincter, allowing urine to pass at the same time. But this isn’t always the case – it is possible, butdifficult, to do one withoutdoingthe other.

Asked by: Kate Selby, Dundee

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