Urination, or deurination, is the process of releasing urine from the bladder. The process can be divided into two phases. The first is the gradual filling of the bubble with urine, until the inner shell is stretched to the maximum limit. The second phase is the urge to deurinate. The urine emptying reflex provides innervation of the bladder. Desires are regulated by the autonomic system with electrically excitable cells in the dorsal brain.
Physiology of the hollow organ of the excretory system
The bladder is located in the pelvic cavity. The organ is a smooth muscle reservoir and consists of two main parts.
- A body that can expand and contract, depending on how much urine it contains.
- The neck, passing into the urethra, connecting the bladder with the external environment. The lower part of the neck is called the posterior urethra.
The mucous urea consists of a multilayer epithelium and connective tissue penetrated by small blood vessels. At the base of the mucosa, there is a bladder triangle and an internal opening of the urethra. In the area of the hole there is a sphincter in the form of a circular muscle, which plays the role of a valve, preventing the involuntary emission of urine.
The smooth muscle of the urea consists of three layers and is called the detrusor. The layers go to the neck of the organ and intertwine with the tissue, which contracts under the influence of excitation pulses. If the violation of the innervation of the bladder is caused by infravesical obstruction, then the detrusor increases greatly.
The posterior urethra rests on the urogenital diaphragm and has a muscle layer, which is called the external sphincter. The main part of the muscle consists of striated beams, it also has smooth fibers. The sphincter muscles are controlled by the nervous system.
Reflex paruria (urination)
As the urea fills up, rapid fluctuations appear in the form of the reaction of myocytes to the effects of an electrochemical pulse. Stimulation of reflex contractions activates the nerve endings of the stretching of the posterior urethra. Nerve impulses from receptors are carried into the sacral segments (roots) of the dorsal brain along the pelvic nerves.
Urination reflex is a collection of periodically recurring processes.
- As the bladder fills with urine, pressure rises.
- The contraction of the bladder activates the sensitive stretch neurons .
- The flow of pulsation increases and enhances the contraction of the wall of the bladder.
- Impulses from contractions are carried along the pelvic nerves to the roots of the spinal cord, and the central nervous system forms a urge to paruria.
- Bladder contractions during urination relax the detrusor and pressure stabilizes.
The reflex of paruria will increase until the act of emitting urine.
Bladder innervation
Impulse transmission is provided by the autonomic NS, dendrites and roots of the spinal cord. The main connection of the bladder with the central nervous system is provided by somatic nerves connected to each other and forming the sacral plexus. Pelvic nerves are composed of afferent (sensitive) and efferent (motor) fibers. Signals about the degree of stretching of the urea are transmitted through afferent fibers. Impulses emanating from the posterior urethra contribute to the activation of urinary reflexes.
Bladder emptying can be reflexive or arbitrary. Unconditional urination is due to neurons of the sympathetic and parasympathetic innervation. Centripetal units of nerve tissue are responsible for meaningful urination. When the organ is filled with urine, the pressure rises, the excited sensors send a signal to the dorsal brain, and then to the cerebral hemispheres.
What is parasympathetic innervation?
The activity of the organ of the excretory system is provided by reflex arcs that are controlled by the spinal centers. Parasympathetic innervation of the bladder is carried out by efferent fibers. They are located in the sacral section of the dorsal brain. In the ganglia of the wall of the urea, preganglionic fibers originate. They innervate the detrusor. The connection of the external sphincter with the central nervous system is carried out through somatic motor fibers. Efferent fibers provoke detrusor contraction and relax the sphincter. With an increase in the tone of the parasympathetic center, urination occurs.
The role of sympathetic innervation
A distinctive feature of sympathetic innervation is the distance from the organ, which is provided by the nerves. The retaining fibers that provide regulation are located in the sacral region of the spinal cord. The sympathetic innervation of the bladder is carried out by the pelvic plexus. Sensitive fibers have a weak effect on wall contractions. But on the other hand, they affect the formation of a feeling of fullness of the bladder, and sometimes pain. It is believed that the defeat of afferent fibers does not lead to disturbances in the process of emptying the urethra.
Bladder innervation and neurology
In the anatomical structure, the detrusor muscle is located so that when it is reduced, the volume of urine decreases. Urination is coordinated by two actions: reduction of smooth muscle of the urea and weakening of the sphincter tension. The processes proceed simultaneously. Neurogenic disorders are characterized by a loss of connection between these processes.
Disorders arise due to impaired bladder innervation in men and women of any age. The reasons can be different: injuries, vascular diseases, benign and malignant neoplasms. The stereotypical reaction of the body emptying and relaxing the sphincter is subject to cortical influences, which provides a meaningful act of removing urine from the body.
Neurogenic disorders of paruria
Any urination disorders are associated with abnormalities in the functioning of the nervous system and have the general term neurogenic bladder. By this concept is meant the dysfunction of the hollow organ of the excretory system due to congenital or acquired pathology of the NS.
There are three forms of disorders of the innervation of the bladder with disorders of urination:
- Hyperreflexivity. Pathology is characterized by frequent desires for deurination. Smooth muscles of the bladder are reduced intensively with a small volume of urine. Overactivity of the bladder is caused by a decrease in the number of M-cholinergic receptors. With a deficiency of nervous regulation in the smooth muscles, the formation of bonds with neighboring cells develops. The muscles of the bladder are very active and immediately respond to a small amount of urine. Detrusor contractions cause bladder hyperactivity syndrome.
- Hyporeflexivity. Pathology is characterized by a decrease or lack of urge to empty. Sluggish and infrequent act of deurination. Even with a large amount of accumulated urine, the detrusor does not respond.
- Reflexivity. Urination occurs spontaneously as soon as the bubble is filled as much as possible.
Innervation disorders
Various pathologies of the brain and dorsal brain contribute to disruption of innervation:
- A disease characterized by the presence of scattered throughout the NS without any localization of foci of connective tissue that replaces the organ (multiple sclerosis).
- Damage to the anterior columns of the dorsal brain and motor nerves. The muscles of the lower sphincter are in tension, there is a violation of the reflex contraction of smooth muscles.
- Spinal dysraphia. This form of violation of the innervation of the bladder and deurination disorder is characterized by spontaneous, not subject to human control, excretion of urine from the body.
- Spinal stenosis.
- The defeat of small blood vessels in diabetes. Pathology extends to all processes of neurons.
- Damage to the bundle of roots of the lower lumbar, coccygeal, sacral spinal nerves.
Symptoms of deurination disorders
Symptoms vary depending on the degree of disorder of the nervous system and the complexity of the disease. With cerebral lesions, strong and frequent urges occur, but the amount of urine is small. The patient complains of poor sleep due to nocturnal diuresis.
Typical signs of a violation of the innervation of the bladder in the sacral region are:
- Urinary incontinence or leakage.
- Atony of the bladder.
- Lack of urge.
Symptoms in the defeat of the supraxtral part are an increase in sphincter muscle tension and hypertension of the bladder. An inflammatory process may also occur due to overflow of the urea and difficulties with emptying it.
Diagnosis and therapy
Recognition of urination disorders and diagnosis are carried out using certain methods:
- Obtaining information by a doctor through questioning.
- Laboratory tests of urine and blood.
- Ultrasound of the urinary organs and abdominal cavity.
- Registration of galvanic activity of muscles (electroneuromyography).
- A study that allows you to measure the flow rate of urine during deurination (uroflowmetry).
- A method for examining the internal structure of the bladder.
- X-ray scanning of the spine and skull.
- In some cases, an MRI can be prescribed.
Treatment is prescribed by a urologist or neurologist. Therapy is comprehensive and includes various methods:
- Medicines that improve blood circulation and innervation of the bladder.
- Drugs that restore the normal functionality of the detrusor and sphincter.
- Pelvic strengthening exercises.
- Physiotherapeutic procedures.
- If necessary, use psychotherapy.
If the above does not bring the proper result, a surgical operation is used.