Physiology of Micturition
The kidneys are responsible for producing urine which travels down the muscular
tubes called ureters and stored in the bladder.
The bladder is made up of the detrusor muscle and two sphincters that hold or
retain urine. The detrusor muscle is a muscle and can contract and relax as needed.
In males, the prostate gland can cause obstruction in the urethra leading to
problems with urination. It has a role in activating sperm.
The micturition center is located in the pons, which is a part of the brainstem.
The spinal cord also plays a crucial role in the process. The signals from the
central nervous system are sent to the urinary tract via nerves. The pudendal nerve
is fired when we try to hold in our urine.
The third nerve is part of the sympathetic nervous system. The brain and pons send
a signal to the thoracic level to stimulate the hypogastric nerve so that we can
retain urine. There are also signals being sent to the sacral level of the spinal
cord. Inhibitory activity is also present.
We have four main components in the urinary system:
* The bladder
* The urethra
* The external sphincter
* The internal sphincter
There are three types of receptors involved in the voiding reflex:
* M3 receptors on the detrusor muscle
* Beta3 receptors on the detrusor muscle
* Receptors on the internal sphincter
When the bladder is full and it's time to urinate, the pelvic afferent nerve fibers
transmit signals from the bladder to the sacral region of the spinal cord.
From there, an interneuron connects with the parasympathetic efferent nerve fibers.
The parasympathetic nerve fibers cause contraction of the detrusor muscle, which
leads to urination continuing until the bladder is empty.
The kidneys are responsible for producing urine which travels down the muscular
tubes called ureters and stored in the bladder.
The bladder is made up of the detrusor muscle and two sphincters that hold or
retain urine. The detrusor muscle is a muscle and can contract and relax as needed.
In males, the prostate gland can cause obstruction in the urethra leading to
problems with urination. It has a role in activating sperm.
The micturition center is located in the pons, which is a part of the brainstem.
The spinal cord also plays a crucial role in the process. The signals from the
central nervous system are sent to the urinary tract via nerves. The pudendal nerve
is fired when we try to hold in our urine.
The third nerve is part of the sympathetic nervous system. The brain and pons send
a signal to the thoracic level to stimulate the hypogastric nerve so that we can
retain urine. There are also signals being sent to the sacral level of the spinal
cord. Inhibitory activity is also present.
We have four main components in the urinary system:
* The bladder
* The urethra
* The external sphincter
* The internal sphincter
There are three types of receptors involved in the voiding reflex:
* M3 receptors on the detrusor muscle
* Beta3 receptors on the detrusor muscle
* Receptors on the internal sphincter
When the bladder is full and it's time to urinate, the pelvic afferent nerve fibers
transmit signals from the bladder to the sacral region of the spinal cord.
From there, an interneuron connects with the parasympathetic efferent nerve fibers.
The parasympathetic nerve fibers cause contraction of the detrusor muscle, which
leads to urination continuing until the bladder is empty.
