BLADDER

BLADDER

The detrusor muscle (detrude vt.) is a layer of the urinary bladder wall made of smooth muscle fibers arranged in spiral, longitudinal, and circular bundles. When the bladder is stretched, this signals the parasympathetic nervous system to contract the detrusor muscle. This encourages the bladder to expel urine through the urethra.

For the urine to exit the bladder, both the autonomically controlled internal sphincter and the voluntarily controlled external sphincter must be opened. Problems with these muscles can lead to incontinence. If the amount of urine reaches 100% of the urinary bladder's capacity, the voluntary sphincter becomes involuntary, and the urine will be ejected instantly.^{[citation needed]}

The urinary bladder usually holds 300-350 ml of urine; a full adult bladder holds about 500-700 mL(male 600, female 500) of urine (this can cause a bladder stretch injury), 15 times its empty volume. As urine accumulates, the rugae flatten and the wall of the bladder thins as it stretches, allowing the bladder to store larger amounts of urine without a significant rise in internal pressure.^[3]

The desire to urinate usually starts when the bladder reaches around 25% of its working volume. At this stage it is easy for the subject, if desired, to resist the urge to urinate. As the bladder continues to fill, the desire to urinate becomes stronger and harder to ignore. Eventually, the bladder will fill to the point where the urge to urinate becomes overwhelming, and the subject will no longer be able to ignore it.

Since the urinary bladder has a transitional epithelium, it does not produce mucus.^[4]

 

^{* 방광의 용량이 800ml 이면 최고용량이 달한 것이다. 이상되면 방광이 늘어지고 터질 우려가 있으니 주의하라.}

^{술을 먹지 말라.}

^{300 ~400 ml에서 오줌이 마려우면 즉시 완전히 비워주라.}

^{오줌을 참지 말라.}