Detrusor muscle

Definition

The detrusor muscle is a smooth muscle layer found in the wall of the bladder that plays a critical role in the storage and expulsion of urine. This muscle contracts to help empty the bladder during urination and relaxes to allow the bladder to fill. Its function is essential for maintaining urinary continence and enabling efficient urine excretion.

5 Must Know Facts For Your Next Test

1. The detrusor muscle is innervated by both sympathetic and parasympathetic fibers, which coordinate its contraction and relaxation during urination.
2. During bladder filling, the detrusor muscle remains relaxed to allow for maximum urine storage, while the internal sphincter remains closed.
3. When it’s time to urinate, signals from the nervous system trigger the detrusor muscle to contract, leading to increased pressure in the bladder and expulsion of urine.
4. Dysfunction of the detrusor muscle can lead to urinary retention or incontinence, significantly affecting a person's quality of life.
5. The detrusor muscle has a unique property called 'plasticity,' allowing it to adapt to varying volumes of urine without losing its ability to contract effectively.

Review Questions

• How does the detrusor muscle contribute to the process of urination?
  • The detrusor muscle plays a vital role in urination by contracting to increase pressure within the bladder, which facilitates the expulsion of urine. During this process, when bladder fullness reaches a certain threshold, nerve signals trigger the detrusor to contract while simultaneously relaxing the internal sphincter. This coordinated action allows urine to flow from the bladder into the urethra and out of the body.
• Discuss how dysfunction in the detrusor muscle can affect urinary health.
  • Dysfunction in the detrusor muscle can lead to conditions such as urinary incontinence or retention. In cases where the detrusor is overactive, involuntary contractions may cause urgency and frequent urination. Conversely, if it is underactive, individuals may struggle to empty their bladders completely, leading to discomfort and increased risk of urinary tract infections. These conditions can have significant impacts on an individual's daily life and overall health.
• Evaluate the impact of autonomic nervous system regulation on detrusor muscle function during bladder filling and voiding.
  • The autonomic nervous system has a profound impact on detrusor muscle function. During bladder filling, sympathetic nerves inhibit detrusor contractions while promoting relaxation, allowing for urine storage. When it's time to void, parasympathetic activation stimulates detrusor contractions while inhibiting sympathetic activity, facilitating urination. This intricate balance ensures proper urinary function; any disruption in autonomic control can lead to urinary dysfunctions such as urgency or retention.

Related terms

Bladder: The organ that stores urine before it is excreted from the body, consisting of a muscular wall lined with transitional epithelium.

Urination: The process of expelling urine from the urinary bladder through the urethra, involving coordination between the detrusor muscle and sphincters.

Autonomic Nervous System: The part of the nervous system that controls involuntary actions, including the regulation of the detrusor muscle during bladder filling and emptying.