Final answer:
The urinary bladder's mucous membrane is lined with folds known as rugae, which allow it to expand and accommodate urine.
Step-by-step explanation:
The urinary bladder is lined with mucous membrane, which is arranged in folds called rugae. These folds allow the bladder to expand as it fills with urine. The lining is made of transitional epithelium, which can flatten and stretch. The rugae unfold and the lining becomes thinner as the bladder expands, accommodating varying volumes of urine.
The urinary bladder is a temporary storage reservoir for urine. It is located in the pelvic cavity, posterior to the symphysis pubis, and below the parietal peritoneum. The size and shape of the urinary bladder varies with the amount of urine it contains and with the pressure it receives from surrounding organs.