Name: 【TED-Ed】Is it bad to hold your pee? - Heba Shaheed
Uploaded: 2016-10-11T03:27:47.000Z
Duration: 3 min 59 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Relative clauses (Restrictive vs. nonrestrictive)

and soon becomes a pressing sensation that's impossible to ignore.

Finally, it's all you can think about, and out of sheer desperation, you go on a hunt for a bathroom until "ahh."

Humans should urinate at least four to six times a day,

but occasionally, the pressures of modern life forces us to clench and hold it in.

How bad is this habit, and how long can our bodies withstand it?

The answers lie in the workings of the bladder,

and oval pouch that sits inside the pelvis.

Surrounding this structure are several other organs

that together make up the whole urinary system.

Constantly trickling down from the kidneys is the yellowish liquid known as urine.

The kidneys make urine from a mix of water and the body's waste products,

funneling the unwanted fluid into two muscular tubes called ureters.

These carry it downward into the hollow organ known as the bladder.

This organ's muscular wall is made of tissue called detrusor muscle

which relaxes as the bladder fills allowing it to inflate like a balloon.

As the bladder gets full,  the detrusor contracts.

The internal urethral sphincter automatically and involuntarily opens,

Whooshing downwards,  the fluid enters the urethra

and stops short at the external urethral sphincter.

When you want to delay urinating, you keep the sphincter closed.

When you want to release it, you can voluntarily open the flood gates.

But how do you sense your bladder's fullness

Inside the layers of detrusor muscles are millions of stretch receptors

They send signals along your nerves to the sacral region in your spinal cord.

A reflex signal travels back to your bladder,

making the detrusor muscle contract slightly,

and increasing the bladder's pressure so you're aware that it's filling up.

Simultaneously, the internal urethral sphincter opens.

The brain can counter it if it's not a good time to urinate

by sending another signal to contract the external urethral sphincter.

With about 150 to 200 milliliters of urine inside of it,

the bladder's muscular wall  is stretched enough

for you to sense  that there's urine within.

At about 400 to 500 milliliters, the pressure becomes uncomfortable.

The bladder can go on stretching, but only to a point.

Most people would lose bladder control before this happens,

such as when a person can't sense the need to urinate,

the pouch can rupture painfully requiring surgery to fix.

your decision to urinate stops the brain's signal to the external urethral sphincter,

causing it to relax  and the bladder to empty.

The external urethral sphincter is one of the muscles of the pelvic floor,

and it provides support to the urethra and bladder neck.

It's lucky we have these  pelvic floor muscles

because placing pressure on the system by coughing,

Instead, the pelvic floor muscles keep the region sealed

or urinating without proper physical support

may over time weaken or overwork that muscular sling.

That can lead to an overactive pelvic floor,

But in the short term, at least, your body and brain have got you covered,

so you can conveniently choose your moment of sweet release.