Urinary incontinence (enuresis) is the loss of bladder control. In children younger than age 3, it’s normal to not have full bladder control. As children get older, they become more able to control their bladder. Wetting is called enuresis when it happens in a child who is old enough to control his or her bladder. Enuresis can happen during the day or at night. It can be a frustrating condition. But it’s important to be patient and remember that it’s not your child’s fault. A child does not have control over enuresis. And there are many ways to treat it and help your child.
There are 4 types of enuresis. A child may have 1 or more of these types:
Nighttime (nocturnal) enuresis. This means wetting during the night. It’s often called bedwetting. It’s the most common type of enuresis.
Daytime (diurnal) enuresis. This is wetting during the day.
Primary enuresis. This happens when a child has not fully mastered toilet training.
Secondary enuresis. This is when a child has a period of dryness, but then returns to having periods of wetting.
What causes enuresis in a child?
Enuresis has many possible causes. The cause of nighttime enuresis often is not known. But possible causes and risk factors may include 1 or more of these:
Attention deficit/hyperactivity disorder (ADHD)
Constipation that puts pressure on the bladder
Delayed bladder development
Not enough antidiuretic hormone (ADH) in the body during sleep
Obstructive sleep apnea
Slower physical development
Structural problems in the urinary tract
Trouble feeling that the bladder is full while asleep
Urinary tract infection
Very deep sleep
Daytime enuresis may be caused by:
Constipation that puts pressure on the bladder
Stopping urine stream before finishing (dysfunctional voiding)
Not going to the bathroom often enough
Not urinating enough when going
Structural problems in the urinary tract
Urinary tract infection
Keeping legs too close together traps urine in the vagina and urine leaks out (vaginal voiding)
Which children are at risk for enuresis?
A child is more at risk for enuresis if he or she:
Doesn’t have regular bathroom habits
Has physical development problems
What are the symptoms of enuresis in a child?
Symptoms can be a bit different for each child. The main symptom is when a child age 5 or older wets their bed or their clothes 2 times a week or more, for at least 3 months. But 1 in 10 children age 7, 1 in 20 children age 10, and 1 in 100 children older than 15 still have at least one episode of nighttime enuresis.
The symptoms of enuresis can seem like other health conditions. Have your child see his or her healthcare provider for a diagnosis.
How is enuresis diagnosed in a child?
Many children may have enuresis from time to time. It can take some children longer than others to learn to control their bladder. Girls often have bladder control before boys. Because of this, enuresis is diagnosed in girls earlier than in boys. Girls may be diagnosed as young as age 5. Boys are not diagnosed until at least age 6.
Your child’s healthcare provider will ask about your child’s health history. Tell the healthcare provider:
If other family members have had enuresis
How often your child urinates during the day
How much your child drinks in the evening
If your child has symptoms such as pain or burning when urinating
If the urine is dark or cloudy or has blood in it
If your child is constipated
If your child has had recent stress in his or her life
The healthcare provider may give your child a physical exam. Your child may also need tests, such as urine tests or blood tests. These are done to look for a health problem, such as an infection or diabetes.
How is enuresis treated in a child?
In most cases, enuresis goes away over time and does not need to be treated. If treatment is needed, many methods can help. These include:
Changes in fluid intake. You may be told to give your child less fluids to drink at certain times of day, or in the evening.
Keeping caffeine out of your child’s diet. Caffeine can be found in cola and many sodas. It is also found in black teas, coffee drinks, and chocolate.
Night waking on a schedule. This means waking your child in the night to go urinate.
Bladder training. This includes exercises and urinating on a schedule.
Using a moisture alarm. This uses a sensor that detects wetness and sounds an alarm. Your child then gets up to use the bathroom.
Medicines. Medicines can boost ADH levels or calm bladder muscles.
Therapy (counseling). Working with a therapist can help your child cope with life changes or other stress.
Work with your child’s healthcare provider to find out the best choices that may help your child.
What are possible complications of enuresis in children?
Possible problems from enuresis can include:
Emotional stress and embarrassment
Skin rash from wet underwear
How can I help my child live with enuresis?
Remember that your child can’t control the problem without help. Don’t scold or blame them.
Make sure your child is not teased by family or friends.
Keep in mind that many children outgrow enuresis.
Protect your child’s mattress bed with a fitted plastic sheet.
Have a change of clothes on hand while out and about.
When should I call my child’s healthcare provider?
Call the healthcare provider if your child has:
Symptoms that don’t get better, or get worse
Key points about enuresis in children
Urinary incontinence (enuresis) is the loss of bladder control. In children under age 3, it’s normal to not have full bladder control. As children get older, they become more able to control their bladder.
It can happen during the day or at night.
It has many possible causes. These include anxiety, constipation, genes, and caffeine.
In many cases, it goes away over time and does not need to be treated.
If treatment is needed, many methods can help. These include changes in fluid intake, reducing caffeine, and urinating on a schedule.
Tips to help you get the most from a visit to your child’s healthcare provider:
Know the reason for the visit and what you want to happen.
Before your visit, write down questions you want answered.
At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.
Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
Ask if your child’s condition can be treated in other ways.
Know why a test or procedure is recommended and what the results could mean.
Know what to expect if your child does not take the medicine or have the test or procedure.
If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.
Gustation is the special sense associated with the tongue. The surface of the tongue, along with the rest of the oral cavity, is lined by a stratified squamous epithelium. Raised bumps called papillae(singular = papilla) contain the structures for gustatory transduction. There are four types of papillae, based on their appearance (Figure 2): circumvallate, foliate, filiform, and fungiform. Within the structure of the papillae are taste buds that contain specialized gustatory receptor cells for the transduction of taste stimuli. These receptor cells are sensitive to the chemicals contained within foods that are ingested, and they release neurotransmitters based on the amount of the chemical in the food. Neurotransmitters from the gustatory cells can activate sensory neurons in the facial, glossopharyngeal, and vagus cranial nerves.
Once the gustatory cells are activated by the taste molecules, they release neurotransmitters onto the dendrites of sensory neurons. These neurons are part of the facial and glossopharyngeal cranial nerves, as well as a component within the vagus nerve dedicated to the gag reflex. The facial nerve connects to taste buds in the anterior third of the tongue. The glossopharyngeal nerve connects to taste buds in the posterior two thirds of the tongue. The vagus nerve connects to taste buds in the extreme posterior of the tongue, verging on the pharynx, which are more sensitive to noxious stimuli such as bitterness.
Like taste, the sense of smell, or olfaction, is also responsive to chemical stimuli. The olfactory receptor neurons are located in a small region within the superior nasal cavity (Figure 3). This region is referred to as the olfactory epithelium and contains bipolar sensory neurons. Each olfactory sensory neuron has dendrites that extend from the apical surface of the epithelium into the mucus lining the cavity. As airborne molecules are inhaled through the nose, they pass over the olfactory epithelial region and dissolve into the mucus. These odorant molecules bind to proteins that keep them dissolved in the mucus and help transport them to the olfactory dendrites. The odorant–protein complex binds to a receptor protein within the cell membrane of an olfactory dendrite. These receptors are G protein–coupled, and will produce a graded membrane potential in the olfactory neurons.
The axon of an olfactory neuron extends from the basal surface of the epithelium, through an olfactory foramen in the cribriform plate of the ethmoid bone, and into the brain. The group of axons called the olfactory tract connect to the olfactory bulb on the ventral surface of the frontal lobe. From there, the axons split to travel to several brain regions. Some travel to the cerebrum, specifically to the primary olfactory cortex that is located in the inferior and medial areas of the temporal lobe. Others project to structures within the limbic system and hypothalamus, where smells become associated with long-term memory and emotional responses. This is how certain smells trigger emotional memories, such as the smell of food associated with one’s birthplace. Smell is the one sensory modality that does not synapse in the thalamus before connecting to the cerebral cortex. This intimate connection between the olfactory system and the cerebral cortex is one reason why smell can be a potent trigger of memories and emotion.
The nasal epithelium, including the olfactory cells, can be harmed by airborne toxic chemicals. Therefore, the olfactory neurons are regularly replaced within the nasal epithelium, after which the axons of the new neurons must find their appropriate connections in the olfactory bulb. These new axons grow along the axons that are already in place in the cranial nerve.
Hearing, or audition, is the transduction of sound waves into a neural signal that is made possible by the structures of the ear (Figure 4). The large, fleshy structure on the lateral aspect of the head is known as the auricle. Some sources will also refer to this structure as the pinna, though that term is more appropriate for a structure that can be moved, such as the external ear of a cat. The C-shaped curves of the auricle direct sound waves toward the auditory canal. The canal enters the skull through the external auditory meatus of the temporal bone. At the end of the auditory canal is the tympanic membrane, or ear drum, which vibrates after it is struck by sound waves. The auricle, ear canal, and tympanic membrane are often referred to as the external ear. The middle ear consists of a space spanned by three small bones called the ossicles. The three ossicles are the malleus, incus, and stapes, which are Latin names that roughly translate to hammer, anvil, and stirrup. The malleus is attached to the tympanic membrane and articulates with the incus. The incus, in turn, articulates with the stapes. The stapes is then attached to the inner ear, where the sound waves will be transduced into a neural signal. The middle ear is connected to the pharynx through the Eustachian tube, which helps equilibrate air pressure across the tympanic membrane. The tube is normally closed but will pop open when the muscles of the pharynx contract during swallowing or yawning.
Along with audition, the inner ear is responsible for encoding information about equilibrium, the sense of balance. A similar mechanoreceptor—a hair cell with stereocilia—senses head position, head movement, and whether our bodies are in motion. These cells are located within the vestibule of the inner ear. Head position is sensed by the utricle and saccule, whereas head movement is sensed by the semicircular canals. The neural signals generated in the vestibular ganglion are transmitted through the vestibulocochlear nerve to the brain stem and cerebellum.
The utricle and saccule are both largely composed of macula tissue (plural = maculae). The macula is composed of hair cells surrounded by support cells. The stereocilia of the hair cells extend into a viscous gel called the otolithic membrane (Figure 10). On top of the otolithic membrane is a layer of calcium carbonate crystals, called otoliths. The otoliths essentially make the otolithic membrane top-heavy. The otolithic membrane moves separately from the macula in response to head movements. Tilting the head causes the otolithic membrane to slide over the macula in the direction of gravity. The moving otolithic membrane, in turn, bends the sterocilia, causing some hair cells to depolarize as others hyperpolarize. The exact position of the head is interpreted by the brain based on the pattern of hair-cell depolarization.
The semicircular canals are three ring-like extensions of the vestibule. One is oriented in the horizontal plane, whereas the other two are oriented in the vertical plane. The anterior and posterior vertical canals are oriented at approximately 45 degrees relative to the sagittal plane (Figure 11). The base of each semicircular canal, where it meets with the vestibule, connects to an enlarged region known as the ampulla. The ampulla contains the hair cells that respond to rotational movement, such as turning the head while saying “no.” The stereocilia of these hair cells extend into the cupula, a membrane that attaches to the top of the ampulla. As the head rotates in a plane parallel to the semicircular canal, the fluid lags, deflecting the cupula in the direction opposite to the head movement. The semicircular canals contain several ampullae, with some oriented horizontally and others oriented vertically. By comparing the relative movements of both the horizontal and vertical ampullae, the vestibular system can detect the direction of most head movements within three-dimensional (3-D) space.
Somatosensation is considered a general sense, as opposed to the special senses discussed in this section. Somatosensation is the group of sensory modalities that are associated with touch, proprioception, and interoception. These modalities include pressure, vibration, light touch, tickle, itch, temperature, pain, proprioception, and kinesthesia. This means that its receptors are not associated with a specialized organ, but are instead spread throughout the body in a variety of organs. Many of the somatosensory receptors are located in the skin, but receptors are also found in muscles, tendons, joint capsules, ligaments, and in the walls of visceral organs.
Two types of somatosensory signals that are transduced by free nerve endings are pain and temperature. These two modalities use thermoreceptors and nociceptors to transduce temperature and pain stimuli, respectively. Temperature receptors are stimulated when local temperatures differ from body temperature. Some thermoreceptors are sensitive to just cold and others to just heat. Nociception is the sensation of potentially damaging stimuli. Mechanical, chemical, or thermal stimuli beyond a set threshold will elicit painful sensations. Stressed or damaged tissues release chemicals that activate receptor proteins in the nociceptors. For example, the sensation of heat associated with spicy foods involves capsaicin, the active molecule in hot peppers. Capsaicin molecules bind to a transmembrane ion channel in nociceptors that is sensitive to temperatures above 37°C. The dynamics of capsaicin binding with this transmembrane ion channel is unusual in that the molecule remains bound for a long time. Because of this, it will decrease the ability of other stimuli to elicit pain sensations through the activated nociceptor. For this reason, capsaicin can be used as a topical analgesic, such as in products such as Icy Hot™.
If you drag your finger across a textured surface, the skin of your finger will vibrate. Such low frequency vibrations are sensed by mechanoreceptors called Merkel cells, also known as type I cutaneous mechanoreceptors. Merkel cells are located in the stratum basale of the epidermis. Deep pressure and vibration is transduced by lamellated (Pacinian) corpuscles, which are receptors with encapsulated endings found deep in the dermis, or subcutaneous tissue. Light touch is transduced by the encapsulated endings known as tactile (Meissner) corpuscles. Follicles are also wrapped in a plexus of nerve endings known as the hair follicle plexus. These nerve endings detect the movement of hair at the surface of the skin, such as when an insect may be walking along the skin. Stretching of the skin is transduced by stretch receptors known as bulbous corpuscles. Bulbous corpuscles are also known as Ruffini corpuscles, or type II cutaneous mechanoreceptors.
Other somatosensory receptors are found in the joints and muscles. Stretch receptors monitor the stretching of tendons, muscles, and the components of joints. For example, have you ever stretched your muscles before or after exercise and noticed that you can only stretch so far before your muscles spasm back to a less stretched state? This spasm is a reflex that is initiated by stretch receptors to avoid muscle tearing. Such stretch receptors can also prevent over-contraction of a muscle. In skeletal muscle tissue, these stretch receptors are called muscle spindles. Golgi tendon organs similarly transduce the stretch levels of tendons. Bulbous corpuscles are also present in joint capsules, where they measure stretch in the components of the skeletal system within the joint.
Vision is the special sense of sight that is based on the transduction of light stimuli received through the eyes. The eyes are located within either orbit in the skull. The bony orbits surround the eyeballs, protecting them and anchoring the soft tissues of the eye (Figure 12). The eyelids, with lashes at their leading edges, help to protect the eye from abrasions by blocking particles that may land on the surface of the eye. The inner surface of each lid is a thin membrane known as the palpebral conjunctiva. The conjunctiva extends over the white areas of the eye (the sclera), connecting the eyelids to the eyeball. Tears are produced by the lacrimal gland, located beneath the lateral edges of the nose. Tears produced by this gland flow through the lacrimal duct to the medial corner of the eye, where the tears flow over the conjunctiva, washing away foreign particles.