What are the steps of micturition reflex?

Normal urination (micturition) occurs in the following stages:

• Urine is made in the kidneys.
• Urine is stored in the bladder.
• The sphincter muscles relax.
• The bladder muscle (detrusor) contracts.
• The bladder is emptied through the urethra and urine is removed from the body.

What is the first step in a micturition reflex?

Bladder Emptying and the Micturition Reflex relaxation of the striated sphincter (somatic innervation) relaxation of the smooth muscle sphincter and opening of the bladder neck (sympathetic innervation) detrusor contraction (parasympathetic innervation)

What are the 3 phases of normal micturition?

This diagram in this article illustrates the three phases: phase 1: filling and storage; phase 2: voiding and phase 3: termination of voiding. The normal bladder fills and empties in cycles.

What are micturition reflexes?

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. One is the dorsal system and the other is the spinothalamic tract.

What is the function of micturition?

Micturition or urination is the process of expelling urine from the bladder. This act is also known as voiding of the bladder. The excretory system in humans includes a pair of kidneys, two ureters, a urinary bladder and a urethra.

What is the voiding reflex?

Reflex voiding is one of the bladder emptying methods, and it relies on spontaneous bladder contractions for voiding. The focus of this investigation is methods to reduce the high urethral resistance and to induce more sustained bladder contractions.

What triggers the micturition reflex?

When the bladder is full of urine, stretch receptors in the bladder wall trigger the micturition reflex. The detrusor muscle that surrounds the bladder contracts. The internal urethral sphincter relaxes, allowing for urine to pass out of the bladder into the urethra. Both of these reactions are involuntary.

What triggers micturition?

Smooth muscle stretch initiates the micturition reflex by activating stretch receptors in the bladder wall. This autonomic reflex causes the detrusor muscle to contract and the internal urethral sphincter muscle to relax, allowing urine to flow into the urethra.

How do you control micturition?

The brain is able to override the micturition reflex by inhibiting the parasympathetic motor nerve fibres to the bladder and reinforcing contraction of the external sphincter (Martini, 2002). The internal sphincter will not open until the external sphincter does.

What triggers the urinary reflex?

What are the factors that control micturition?

The muscles controlling micturition are controlled by the autonomic and somatic nervous systems. During the storage phase, the internal urethral sphincter remains tense and the detrusor muscle relaxed by sympathetic stimulation.

Which part of the brain controls the micturition reflex?

The neuroscience of urination. The medial prefrontal cortex (mPFC) is located behind the forehead at the front of the cortex (green), while the pontine micturition center (PMC) and the locus coeruleus (LC) are located within a part of the brainstem known as the pons (blue).

What is the function of the micturition reflex?

The Micturition Reflex 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 low bladder volumes, the afferent firing of the stretch receptors is low, and results in relaxation of the bladder.

What are the two phases of micturition in the body?

Micturition consists of two phases: The storage phase: A relaxed bladder in which urine slowly fills the bladder. The voiding phase: A contracted bladder that forces the external sphincter open and discharges urine through the urethra.

How is micturition regulated in the central nervous system?

Central nervous control of micturition and urine storage The micturition reflex is one of the autonomic reflexes, but the release of urine is regulated by voluntary neural mechanisms that involve centers in the brain and spinal cord.

Where are micturition impulses carried in the spinal cord?

Impulses from the filling bladder are carried to the spinal cord via the pelvic and hypogastric nerves, whereas the pudendal and hypogastric nerves carry impulses from the neck of the bladder and the urethra. The pontine micturition center (PMC) in the brainstem is activated via afferent signals from the urinary bladder as it is filling.