When does the detrusor muscle contract?
Andrew Campbell
Published May 14, 2026
The detrusor muscle remains relaxed to allow the bladder to store urine, and contracts during urination to release urine. Related are the urethral sphincter muscles which envelop the urethra to control the flow of urine when they contract.
Accordingly, when the detrusor muscle contracts the sphincters open?
At about 500 ml, detrusor muscle contractions begin to force open the internal urethral sphincter. Unless the external urethral sphincter is powerful enough to prevent it, micturition (urination) will occur involuntarily.
Also Know, what is detrusor reflex? The micturition reflex is a bladder-to-bladder contraction reflex for which the reflex center is located in the rostral pontine tegmentum (pontine micturition center: PMC). There are two afferent pathways from the bladder to the brain. The activity of these neurons is affected by the pontine activity.
Also, which nervous system causes contraction of the detrusor?
1. The parasympathetic nervous system is responsible for maintaining normal bladder function, contracting the bladder smooth muscle (detrusor) and relaxing the bladder outlet during micturition.
Does the Trigone contract?
Two electrodes were applied to the bladder and one to the trigone. These findings suggest that the trigone does not contract during voiding, thus refuting the claim that the trigone is responsible for preventing ureterovesical reflux on voiding.
Related Question Answers
What weakens the detrusor muscle?
Some causes of detrusor areflexia include spinal cord injury, fractures, herniated disc, and infections. Damage to the detrusor muscle from chronic overdistention can lead to the fibrosis of the muscle with weakness in the contraction of the muscle. This condition is often referred to as a myogenic bladder.What relaxes the detrusor muscle?
The detrusor muscle remains relaxed to allow the bladder to store urine, and contracts during urination to release urine.| Detrusor muscle | |
|---|---|
| Actions | Sympathetic relaxes, to store urine Parasympathetic contracts, to urinate |
| Identifiers | |
| Latin | musculus detrusor vesicae urinariae |
What muscle is used to stop peeing?
The muscles you use to stop your urine flow are your pelvic floor muscles.Is the detrusor muscle under voluntary control?
The detrusor is the smooth or involuntary muscle of the bladder wall. The urethral muscles consist of the external and internal sphincter. The internal sphincter and detrusor muscle are both under autonomic control. The external sphincter, however, is a voluntary muscle under the control of voluntary nerves.What is detrusor failure?
Detrusor underactivity, or underactive bladder (UAB), is defined as a contraction of reduced strength and/or duration resulting in prolonged bladder emptying and/or a failure to achieve complete bladder emptying within a normal time span. UAB can be observed in many neurologic conditions and myogenic failure.What is detrusor overactivity?
Detrusor overactivity is defined as a urodynamic observation characterized by involuntary detrusor contractions during the filling phase that may be spontaneous or provoked. Detrusor overactivity is subdivided into idiopathic detrusor overactivity and neurogenic detrusor overactivity.How do you relax the urinary sphincter muscle?
Diazepam (Valium) can be taken as a muscle relaxant or to reduce anxiety. Drugs called alpha-adrenergic blockers can also be used to relax the sphincter. Examples of these drugs are alfuzosin (UroXatral), tamsulosin (Flomax), terazosin (Hytrin), and doxazosin (Cardura).What does the sympathetic nervous system do to the bladder?
Answer. When the sympathetic nervous system is active, it causes the bladder to increase its capacity without increasing detrusor resting pressure (accommodation) and stimulates the internal urinary sphincter to remain tightly closed.What relaxes the bladder?
Anticholinergic medicines help relax the muscles of the bladder. They include oxybutynin (Oxytrol, Ditropan), tolterodine (Detrol), darifenacin (Enablex), trospium (Sanctura), and solifenacin (VESIcare). Beta agonist drugs can also help relax the muscles of the bladder.Does sympathetic nervous system relax bladder?
The sympathetic system has a long postganglionic chain that runs with the hypogastric nerve to synapse with alpha and beta receptors in the bladder wall and the bladder neck or internal sphincter. Beta receptors are responsible for mediating relaxation of the bladder with filling.Which neurotransmitter causes detrusor contraction and relaxation?
The main neurotransmitter eliciting detrusor contraction is ACh, acting via M3 receptors; ATP, acting via P2X purinergic receptors may also elicit detrusor contraction in the setting of inflammation or other conditions associated with detrusor overactivity.Why does the bladder relax in fight or flight?
When we're under stress, our fight-or-flight response tends to kick in; this triggers a release of hormones, which disrupt the usual hormones which keep the bladder relaxed, causing it to contract. This results in people feeling the need to urinate, or even involuntarily urinating in some cases.What is the meaning of detrusor?
[ dĭ-trōō′z?r ] n. A muscle that pushes down, such as the muscle that expels urine from the bladder.What causes detrusor instability?
OAB may be associated with Parkinson's disease, spinal cord injury, diabetic neuropathy, multiple sclerosis, dementia or stroke; however, most cases have no specific cause. In men, urge incontinence may be due to neurological disease or an enlarged prostate (benign prostatic hypertrophy or prostate cancer).Which sphincter Do you have voluntary control over?
external sphincterWhat is the voiding reflex?
Reflex voiding is one of the bladder emptying methods, and it relies on spontaneous bladder contractions for voiding. These contractions occur with normal bladder filling or can be induced with suprapubic tapping and hair pulling.Is overactive bladder a disability?
Urinary or bowel incontinence is rarely severe enough to qualify for benefits on its own and incontinence is not specifically listed as a condition one can collect disability for. However, loss of bladder control is nearly always a symptom of a more serious disease.What does self voiding mean?
1. a technique of bladder training in which the patient is instructed to urinate according to a predetermined schedule, usually beginning at intervals as often as one hour to an hour and a half.What nerve controls urination?
The lower urinary tract is innervated by 3 sets of peripheral nerves: pelvic parasympathetic nerves, which arise at the sacral level of the spinal cord, excite the bladder, and relax the urethra; lumbar sympathetic nerves, which inhibit the bladder body and excite the bladder base and urethra; and pudendal nerves,What allows us to postpone bladder emptying temporarily?
When stored urine has been forced past the internal sphincter into the upper part of the urethra, we feel the urge to void. The external urethral sphincter can then be voluntarily relaxed to allow voiding, or we can choose to keep it closed and postpone bladder emptying temporarily.What level of spinal cord injury causes urinary incontinence?
If you have an injury lower in your spinal cord at or below anatomic level of TH12/L1 you lose muscle tone in the bladder and sphincter. Due to the fact that this region is responsible for reflex bladder emptying, a complete injury results in areflexia of the detrusor (missing contraction of the bladder muscle).Does the urinary system provide homeostasis to the blood only?
In addition to maintaining fluid homeostasis in the body, the urinary system controls red blood cell production by secreting the hormone erythropoietin. The urinary system also plays a role in maintaining normal blood pressure by secreting the enzyme renin.Which part of the brain controls the urination reflex?
The pons is a major relay center between the brain and the bladder. The mechanical process of urination is coordinated by the pons in the area known as the pontine micturition center (PMC). The conscious sensations associated with bladder activity are transmitted to the pons from the cerebral cortex.How is the urge to urinate consciously perceived?
The state of the micturition reflex system is dependent on both a conscious signal from the brain and the firing rate of sensory stretch fibers from the bladder and urethra. At high bladder volumes, the afferent firing of the stretch receptors increases, and causes a conscious sensation of urinary urge.What is the function of Trigone?
The signals become stronger as the bladder continues to fill. Embryologically, the trigone of the bladder is derived from the caudal end of mesonephric ducts, which is of mesodermal origin (the rest of the bladder is endodermal).| Trigone of urinary bladder | |
|---|---|
| TA2 | 3421 |
| FMA | 15910 |
| Anatomical terminology | |
Why is the Trigone clinically important?
Why is the trigone of the urinary bladder clinically important? It causes kidney-collecting ducts to reabsorb more water.Which condition occurs when the detrusor muscle in the wall of the bladder is too active?
Overactive bladder is caused by a malfunction of the detrusor muscle, which in turn can be cased by: Nerve damage caused by abdominal trauma, pelvic trauma or surgery.What are the 3 layers of the bladder?
The bladder wall is made of many layers, including:- Urothelium or transitional epithelium. This is the layer of cells that lines the inside of the kidneys, ureters, bladder, and urethra.
- Lamina propria. This is the next layer around the urothelium.
- Detrusor muscle (muscularis propria).
- Fatty connective tissue.
