Question

Some urine has been formed by kidney nephrons. Follow that urine through the remaining kidney and urinary system structrures. Describe how urine is stored, and how micturition occurs.

Answer 1

Urine is produced in the kidney and travel through uterus into urinary bladder, it is a hollow,muscular and elastic organ that stores urine.
When the bladder is empty it is in pyrimidal shape and it expands when urine fills by the detrusor, the smooth muscle surrounds the bladder and the fold called rugae,the line the interior wall.it gives elasticity to the bladder.The bladder include a funnel shaped region on their surface called trigone ,formed by two urethral orifices and internal urethra.urine flow into bladder via urethral orifices.

Micturition is the process of urination or voiding.The internal and external urethral sphincters are the muscles that regulate flow of urine.The internal sphincter is involuntary and it surrounds opening of bladder to urethra and relaxes for urination to occur.External sphincter is involuntary and it surrounds urethra outside bladder.It also relaxes for urination to occur. Detrusor muscle and folds called rugae allows expansion of bladder.Urine is flowed into bladder by urethral orifice and out by internal sphincter.When bladder is full,detrusor muscle contracts and internal and external sphincter relax causing micturition.

A feeling of fullness in bladder develops when It reaches about 200 mL ...detrusor muscle contract and then an urge to urinate develop .When it cross 500mL and if the exterior sphincter cannot overcome the urge,urination occur involuntarily.
The act of urination voluntarily will begin at age of 2 or 3, based on the voluntary control of external sphincter and the signals from it to the cerebral cortex.