Urinary Bladder

Definition

The urinary bladder is a hollow, muscular organ that stores urine before it is eliminated from the body. It is an essential part of the urinary system, responsible for collecting and temporarily holding urine produced by the kidneys until it can be voluntarily expelled through the urethra.

5 Must Know Facts For Your Next Test

1. The urinary bladder is located in the pelvic cavity, behind the pubic symphysis and in front of the rectum.
2. The bladder can expand to hold up to 500 milliliters of urine before the sensation of needing to urinate occurs.
3. The bladder wall consists of an outer serous layer, a middle muscular layer (detrusor muscle), and an inner mucosal layer.
4. The ureters, which carry urine from the kidneys, enter the bladder at the trigone, a triangular-shaped area on the interior surface.
5. The internal urethral sphincter, a smooth muscle, controls the flow of urine from the bladder into the urethra during urination.

Review Questions

• Describe the location and basic structure of the urinary bladder.
  • The urinary bladder is located in the pelvic cavity, behind the pubic symphysis and in front of the rectum. It is a hollow, muscular organ with an outer serous layer, a middle muscular layer (detrusor muscle), and an inner mucosal layer. The ureters, which carry urine from the kidneys, enter the bladder at the trigone, a triangular-shaped area on the interior surface. The internal urethral sphincter, a smooth muscle, controls the flow of urine from the bladder into the urethra during urination.
• Explain the role of the detrusor muscle in the function of the urinary bladder.
  • The detrusor muscle is the smooth muscle layer in the wall of the bladder that contracts to expel urine during urination. This muscle plays a crucial role in the bladder's ability to store and release urine. When the bladder fills with urine, the detrusor muscle relaxes to allow the bladder to expand and accommodate the increasing volume. When it is time to urinate, the detrusor muscle contracts, creating pressure within the bladder that forces the urine out through the urethra.
• Analyze how the location and structure of the urinary bladder contribute to its function in the urinary system.
  • The strategic location of the urinary bladder within the pelvic cavity allows it to effectively store and release urine. Its position behind the pubic symphysis and in front of the rectum provides anatomical protection and stability. The bladder's muscular wall, with the detrusor muscle, enables it to expand and contract, allowing it to temporarily hold urine produced by the kidneys and then expel it through the urethra at the appropriate time. The trigone, where the ureters enter the bladder, is designed to prevent the backflow of urine, ensuring the unidirectional movement of urine from the kidneys to the bladder and out of the body. This integration of the bladder's location and structural features is essential for the proper functioning of the urinary system.

Related terms

Urethra: The urethra is the tube that carries urine from the bladder out of the body. It allows for the controlled release of urine from the bladder.

Trigone: The trigone is the triangular-shaped area on the interior surface of the bladder, located between the two ureteral orifices and the internal urethral orifice.

Detrusor Muscle:

The detrusor muscle is the smooth muscle layer in the wall of the bladder that contracts to expel urine during urination.