What is the bladder capacity?

Generally speaking, the bladder capacity of an adult is about 300 to 500 ml. Of course, the bladder capacity is closely related to individual differences. For ordinary people, you must pay attention to the health of the bladder and cannot hold urine at ordinary times. Holding urine can cause great damage to the bladder muscles and affect the normal storage of urine. It may even cause cystitis, and may also lead to the occurrence of diseases such as prostatitis or urethritis.

What is the bladder capacity?

The adult bladder is located in the pelvis and is an organ that stores urine. The infant's bladder is higher and located in the abdomen, with its neck close to the upper edge of the pubic symphysis. By around the age of 20, the bladder gradually descends into the pelvis due to the expansion of the pubic bone, the evolution of the role of the sacrum, and the tilt and depth of the pelvis. When empty, the bladder is cone-shaped. When full, it becomes oval in shape, with the top rising above the pubic bone. The adult bladder capacity is 300 to 500 ml of urine. There is a triangular area on the inner surface of the bladder base, called the bladder triangle, which is located between the line connecting the two ureteral orifices and the internal urethral orifice. At the lower part of the bladder, there is the internal opening of the urethra, and the two posterior upper corners of the bladder triangle are where the ureters open.

1. Bladder wall

The bladder wall is composed of three layers of tissue: the mucosa, muscularis, and adventitia. The muscular layer is composed of smooth muscle fibers, called the detrusor. The contraction of the detrusor increases the pressure inside the bladder and forces urine to be discharged from the urethra. There is a thick circular muscle at the junction of the bladder and urethra, which forms the internal urethral sphincter. The contraction of the sphincter closes the internal opening of the urethra, preventing urine from leaking out of the bladder.

2. Serous layer

The serosa is a honeycombed fatty tissue that surrounds the posterior and superior sides and top of the bladder.

3. Muscle layer

Muscle layer: ① Detrusor muscle: Detrusor muscle is the general term for the bladder wall muscles, which are composed of smooth muscle. It is divided into three layers: the inner and outer layers are longitudinal muscles, and the middle layer is circular muscles. The circular muscle is the thickest and strongest. ② Bladder trigone muscle: The trigone muscle is the muscle tissue outside the bladder wall layer. It originates from the longitudinal muscle fibers of the ureter and spreads out inward, downward, and forward in a fan-like manner. The part that extends inward and combines with the opposite side muscle to form the interureteric ridge, which extends downward and forward to the posterior urethra and is the Bell muscle. There is another group of left and right muscle fibers that cross in the center of the triangle to become the bottom muscle of the triangle.

4. Mucous membrane

The mucosal layer is a very thin layer of transitional epithelial tissue, which is continuous with the ureter and urethral mucosa. The mucosa is very smooth in the triangular area because it is closely connected to the underlying muscles, but it has prominent folds in other areas, which disappear when the bladder is full. The mucosal layer contains glandular tissue, especially in the bladder neck and trigone. The submucosal layer only exists in the area outside the triangle. It is a loose tissue with rich blood vessels and elasticity. It tightly connects the mucosa and muscle layer to each other.