bladder
膀 centers on the bladder, the organ that stores urine before it is expelled.
膀 combines the flesh radical ⺼ (月) with 旁, which likely contributes the sound. The character specifically denotes the bladder as a body part.
The flesh radical ⺼ on the left indicates a body part, and the right side 旁 looks like a container with a lid. Picture the bladder as a fleshy container that holds liquid.
For ボウ, imagine a bow-shaped bladder filling up: bow -> ボウ, and the bladder stretches like a bow.
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urinary bladder; urinary cyst; vesica urinaria; bladder
artificial bladder; artificial urinary bladder
acute cystitis
sphincter muscle of urinary bladder
cystitis; inflammation of the bladder
bladder cancer
bladder stone; vesical calculus; cystolith
cystography; cystogram
cystoscope