101-578: [REDACTED] Look up faint in Wiktionary, the free dictionary. Faint or Fainting may refer to: Syncope (medicine) , a medical term for fainting Lightheadedness , in the sense of "feeling faint" "Faint" (song) , by Linkin Park The Faint , a dance-punk/rock band See also [ edit ] Feint (disambiguation) All pages with titles containing Faint Topics referred to by
202-478: A Holter monitor may be used. This is a portable ECG device that can record the wearer's heart rhythms during daily activities over an extended period of time. Since fainting usually does not occur upon command, a Holter monitor can provide a better understanding of the heart's activity during fainting episodes. For people with more than two episodes of syncope and no diagnosis on "routine testing", an insertable cardiac monitor might be used. It lasts 28–36 months and
303-683: A pulmonary embolism or aortic dissection , among others. The most common cause of cardiac syncope is cardiac arrhythmia (abnormal heart rhythm) wherein the heart beats too slowly, too rapidly, or too irregularly to pump enough blood to the brain. Some arrhythmias can be life-threatening. Two major groups of arrhythmias are bradycardia and tachycardia . Bradycardia can be caused by heart blocks . Tachycardias include SVT ( supraventricular tachycardia ) and VT ( ventricular tachycardia ). SVT does not cause syncope except in Wolff-Parkinson-White syndrome . Ventricular tachycardia originate in
404-505: A squat toilet is used for urination in a squatting position. Women averting contact with a toilet seat may employ a partial squatting position (or "hovering"), similar to using a female urinal . However, this may not completely void the bladder . Females may also urinate while standing, and while clothed. It is common for women in various regions of Africa to use this position when they urinate, as do women in Laos . Herodotus described
505-410: A 12-lead ECG. The ECG is useful to detect an abnormal heart rhythm, poor blood flow to the heart muscle and other electrical issues, such as long QT syndrome and Brugada syndrome . Heart related causes also often have little history of a prodrome . Low blood pressure and a fast heart rate after the event may indicate blood loss or dehydration, while low blood oxygen levels may be seen following
606-401: A cause of syncope also is not indicated. Although sometimes investigated as a cause of syncope, carotid artery problems are unlikely to cause that condition. Additionally an electroencephalogram (EEG) is generally not recommended. A bedside ultrasound may be performed to rule out abdominal aortic aneurysm in people with concerning history or presentation. Urination Urination
707-403: A contraction of the perineal muscles. The external sphincter can be contracted voluntarily, which will prevent urine from passing down the urethra. The need to urinate is experienced as an uncomfortable, full feeling. It is highly correlated with the fullness of the bladder. In many males the feeling of the need to urinate can be sensed at the base of the penis as well as the bladder, even though
808-424: A different phenomenon occurs, where urine is discharged as droplets, and urination in smaller mammals, such as mice and rats, can occur in less than a second. The posited benefits of faster voiding are decreased risk of predation (while voiding) and decreased risk of urinary tract infection. The mechanism by which voluntary urination is initiated remains unsettled. One possibility is that the voluntary relaxation of
909-633: A fast heart rate after the event may indicate blood loss or dehydration, while low blood oxygen levels may be seen following the event in those with pulmonary embolism. More specific tests such as implantable loop recorders , tilt table testing or carotid sinus massage may be useful in uncertain cases. Computed tomography (CT) is generally not required unless specific concerns are present. Other causes of similar symptoms that should be considered include seizure , stroke , concussion , low blood oxygen , low blood sugar , drug intoxication and some psychiatric disorders among others. Treatment depends on
1010-435: A genetic component to syncope. A medical history, physical examination, and electrocardiogram (ECG) are the most effective ways to determine the underlying cause. The ECG is useful to detect an abnormal heart rhythm, poor blood flow to the heart muscle and other electrical issues, such as long QT syndrome and Brugada syndrome . Heart related causes also often have little history of a prodrome . Low blood pressure and
1111-721: A highly desirable option. Women generally need to urinate more frequently than men, but as opposed to the common misconception, it is not due to having smaller bladders. Resisting the urge to urinate because of lack of facilities can promote urinary tract infections which can lead to more serious infections and, in rare situations, can cause renal damage in women. Female urination devices are available to help women to urinate discreetly, as well to help them urinate while standing. Techniques and body postures while urinating vary across cultures. Different anatomical conditions in men and women may presume different postures, yet these are largely shaped by cultural norms, types of clothing, and
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#17328583080421212-490: A long post-ictal state is indicative of syncope rather than an akinetic seizure. Some rare forms, such as hair-grooming syncope are of an unknown cause. Subarachnoid hemorrhage may result in syncope. Often this is in combination with sudden, severe headache. It may occur as a result of a ruptured aneurysm or head trauma. Heat syncope occurs when heat exposure causes decreased blood volume and peripheral vasodilatation. Position changes, especially during vigorous exercise in
1313-431: A low-salt diet in the absence of any salt-retaining tendency. Or heat causing vaso-dilation and worsening the effect of the relatively insufficient blood volume. The next stage is the adrenergic response. If there is underlying fear or anxiety (e.g., social circumstances), or acute fear (e.g., acute threat, needle phobia ), the vaso-motor centre demands an increased pumping action by the heart (flight or fight response). This
1414-404: A mild mass reflex. In some instances, the voiding reflex becomes hyperactive. Bladder capacity is reduced and the wall becomes hypertrophied. This type of bladder is sometimes called the spastic neurogenic bladder. The reflex hyperactivity is made worse, and may be caused, by infection in the bladder wall. A common technique used in many developing nations involves holding the child by the backs of
1515-463: A place is, the more public urination tends to be objectionable. In the countryside, it is more acceptable than in a street in a town, where it may be a common transgression. Often this is done after the consumption of alcoholic beverages , which causes production of additional urine as well as a reduction of inhibitions . One proposed way to inhibit public urination due to drunkenness is the Urilift , which
1616-563: A presenting symptom of a myocardial infarction. In general, faints caused by structural disease of the heart or blood vessels are particularly important to recognize, as they are warning of potentially life-threatening conditions. Among other conditions prone to trigger syncope (by either hemodynamic compromise or by a neural reflex mechanism, or both), some of the most important are hypertrophic cardiomyopathy , acute aortic dissection, pericardial tamponade, pulmonary embolism, aortic stenosis, and pulmonary hypertension . Sick sinus syndrome ,
1717-474: A public place other than at a public urinal varies with the situation and with customs. Potential disadvantages include a dislike of the smell of urine, and exposure of genitals. It can be avoided or mitigated by going to a quiet place and/or facing a tree or wall if urinating standing up, or while squatting, hiding the back behind walls, bushes, or a tree. Portable toilets (port-a-potties) are frequently placed in outdoor situations where no immediate facility
1818-512: A rare cause of syncope. Narcolepsy may present with sudden loss of consciousness similar to syncope. A medical history, physical examination, and electrocardiogram (ECG) are the most effective ways to determine the underlying cause of syncope. Guidelines from the American College of Emergency Physicians and American Heart Association recommend a syncope workup include a thorough medical history, physical exam with orthostatic vitals, and
1919-452: A sinus node dysfunction, causing alternating bradycardia and tachycardia. Often there is a long pause (asystole) between heartbeats. Adams-Stokes syndrome is a cardiac syncope that occurs with seizures caused by complete or incomplete heart block. Symptoms include deep and fast respiration, weak and slow pulse, and respiratory pauses that may last for 60 seconds. Subclavian steal syndrome arises from retrograde (reversed) flow of blood in
2020-447: A specific activity such as urination , vomiting , or coughing . Neurally mediated syncope may also occur when an area in the neck known as the carotid sinus is pressed. The third type of syncope is due to a drop in blood pressure when changing position such as when standing up. This is often due to medications that a person is taking but may also be related to dehydration , significant bleeding or infection . There also seems to be
2121-449: A symptom. The respiratory system may compensate for dropping oxygen levels through hyperventilation , though a sudden ischemic episode may also proceed faster than the respiratory system can respond. These processes cause the typical symptoms of fainting: pale skin, rapid breathing, nausea, and weakness of the limbs, particularly of the legs. If the ischemia is intense or prolonged, limb weakness progresses to collapse. The weakness of
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#17328583080422222-487: A very slight rise as the bladder is filled. This phenomenon is a manifestation of the law of Laplace , which states that the pressure in a spherical viscus is equal to twice the wall tension divided by the radius. In the case of the bladder, the tension increases as the organ fills, but so does the radius. Therefore, the pressure increase is slight until the organ is relatively full. The bladder's smooth muscle has some inherent contractile activity; however, when its nerve supply
2323-410: A wide QRS with a slurred upstroke. Signs of ARVD/C include T wave inversion and epsilon waves in lead V1 to V3. It is estimated that from 20 to 50% of people have an abnormal ECG. However, while an ECG may identify conditions such as atrial fibrillation , heart block, or a new or old heart attack, it typically does not provide a definite diagnosis for the underlying cause for fainting. Sometimes,
2424-467: Is available. These need to be serviced (cleaned out) on a regular basis. Urination in a heavily wooded area is generally harmless, actually saves water, and may be condoned for males (and less commonly, females) in certain situations as long as common sense is used. Examples (depending on circumstances) include activities such as camping, hiking, delivery driving, cross country running, rural fishing, amateur baseball, golf, etc. The more developed and crowded
2525-425: Is called presyncope . It is recommended that presyncope be treated the same as syncope. Causes range from non-serious to potentially fatal. There are three broad categories of causes: heart or blood vessel related; reflex , also known as neurally mediated; and orthostatic hypotension . Issues with the heart and blood vessels are the cause in about 10% and typically the most serious while neurally mediated
2626-410: Is called a diuretic , whereas antidiuretics decrease the production of urine by the kidneys. There are three major types of bladder dysfunction due to neural lesions: (1) the type due to interruption of the afferent nerves from the bladder; (2) the type due to interruption of both afferent and efferent nerves; and (3) the type due to interruption of facilitatory and inhibitory pathways descending from
2727-401: Is characterised by loss of consciousness on swallowing; it has been associated not only with ingestion of solid food, but also with carbonated and ice-cold beverages, and even belching." Fainting can occur in "cough syncope" following severe fits of coughing , such as that associated with pertussis or "whooping cough". Neurally mediated syncope may also occur when an area in the neck known as
2828-524: Is common. Cultures around the world differ regarding socially accepted voiding positions and preferences: in the Middle-East and Asia, the squatting position was more prevalent, while in the Western world the standing and sitting positions were more common. For practising Muslim men, the genital modesty of squatting is also associated with proper cleanliness requirements or awrah . In Western culture,
2929-463: Is different from Wikidata All article disambiguation pages All disambiguation pages Syncope (medicine) syncope Syncope , commonly known as fainting or passing out , is a loss of consciousness and muscle strength characterized by a fast onset, short duration, and spontaneous recovery. It is caused by a decrease in blood flow to the brain , typically from low blood pressure . There are sometimes symptoms before
3030-454: Is disguised as a normal manhole by day but raises out of the ground at night to provide a public restroom for bar-goers. In many places, public urination is punishable by fines, though attitudes vary widely by country. In general, females are less likely to urinate in public than males. Women and girls, unlike men and boys, are restricted in where they can urinate conveniently and discreetly. The 5th-century BC historian Herodotus , writing on
3131-433: Is generally not required unless specific concerns are present. Other causes of similar symptoms that should be considered include seizure , stroke , concussion , low blood oxygen , low blood sugar , drug intoxication and some psychiatric disorders among others. Treatment depends on the underlying cause. Those who are considered at high risk following investigation may be admitted to hospital for further monitoring of
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3232-434: Is inserted just beneath the skin in the upper chest area. Echocardiography and ischemia testing may be recommended for cases where initial evaluation and ECG testing is nondiagnostic. For people with uncomplicated syncope (without seizures and a normal neurological exam) computed tomography or MRI is not generally needed. Likewise, using carotid ultrasonography on the premise of identifying carotid artery disease as
3333-493: Is intact, stretch receptors in the bladder wall initiate a reflex contraction that has a lower threshold than the inherent contractile response of the muscle. Action potentials carried by sensory neurons from stretch receptors in the urinary bladder wall travel to the sacral segments of the spinal cord through the pelvic nerves. Since bladder wall stretch is low during the storage phase, these afferent neurons fire at low frequencies. Low-frequency afferent signals cause relaxation of
3434-458: Is often due to an underlying disorder or medication use and is accompanied by other hypoadrenergic signs . The central ischemic response is triggered by an inadequate supply of oxygenated blood in the brain. Common examples include strokes and transient ischemic attacks . While these conditions often impair consciousness they rarely meet the medical definition of syncope. Vertebrobasilar transient ischemic attacks may produce true syncope as
3535-510: Is often possible to manage these symptoms with specific behavioral techniques. Another evolutionary psychology view is that some forms of fainting are non-verbal signals that developed in response to increased inter-group aggression during the paleolithic . A non-combatant who has fainted signals that they are not a threat. This would explain the association between fainting and stimuli such as bloodletting and injuries seen in blood-injection-injury type phobias such as needle phobia as well as
3636-512: Is one of the most common types which may occur in response to any of a variety of triggers, such as scary, embarrassing or uneasy situations, during blood drawing, or moments of sudden unusually high stress. There are many different syncope syndromes which all fall under the umbrella of vasovagal syncope related by the same central mechanism. First, the person is usually predisposed to decreased blood pressure by various environmental factors. A lower than expected blood volume, for instance, from taking
3737-451: Is possible for both sexes to urinate into bottles in case of emergencies. The technique can help children to urinate discreetly inside cars and in other places without being seen by others. A female urination device can assist women and girls in urinating while standing or into a bottle. In microgravity , excrement tends to float freely, so astronauts use a specially designed space toilet , which uses suction to collect and recycle urine;
3838-482: Is set in motion via the adrenergic (sympathetic) outflow from the brain, but the heart is unable to meet requirements because of the low blood volume, or decreased return. A feedback response to the medulla is triggered via the afferent vagus nerve . The high (ineffective) sympathetic activity is thereby modulated by vagal (parasympathetic) outflow leading to excessive slowing of heart rate. The abnormality lies in this excessive vagal response causing loss of blood flow to
3939-677: Is slow to respond to the stress of upright posture. If the blood pressure is not adequately maintained during standing, faints may develop. However, the resulting "transient orthostatic hypotension" does not necessarily signal any serious underlying disease. It is as common or perhaps even more common than vasovagal syncope. This may be due to medications, dehydration , significant bleeding or infection . The most susceptible individuals are elderly frail individuals, or persons who are dehydrated from hot environments or inadequate fluid intake. For example, medical students would be at risk for orthostatic hypotensive syncope while observing long surgeries in
4040-508: Is structural damage to the autonomic nervous system due to systemic diseases (e.g., amyloidosis or diabetes) or in neurological diseases (e.g., Parkinson's disease). Hyperadrenergic orthostatic hypotension refers to an orthostatic drop in blood pressure despite high levels of sympathetic adrenergic response. This occurs when a person with normal physiology is unable to compensate for >20% loss in intravascular volume. This may be due to blood loss, dehydration or third-spacing . On standing
4141-414: Is the cause of syncope in less than 1% of people who present to the emergency department. Orthostatic (postural) hypotensive syncope is caused primarily by an excessive drop in blood pressure when standing up from a previous position of lying or sitting down. When the head is elevated above the feet the pull of gravity causes blood pressure in the head to drop. This is sensed by stretch receptors in
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4242-429: Is the most common. Heart related causes may include an abnormal heart rhythm , problems with the heart valves or heart muscle and blockages of blood vessels from a pulmonary embolism or aortic dissection among others. Neurally mediated syncope occurs when blood vessels expand and heart rate decreases inappropriately. This may occur from either a triggering event such as exposure to blood, pain, strong feelings or
4343-506: Is the process of learning to restrict urination to socially approved times and situations. Consequently, young children sometimes develop nocturnal enuresis . It is socially more accepted and more environmentally hygienic for those who are able, especially when indoors and in outdoor urban or suburban areas, to urinate in a toilet . Public toilets may have urinals , usually for males, although female urinals exist, designed to be used in various ways. Acceptability of outdoor urination in
4444-545: Is the release of urine from the bladder to the outside of the body. Urine is released through the urethra and exits the penis or vulva through the urinary meatus in placental mammals , but is released through the cloaca in other vertebrates . It is the urinary system 's form of excretion . It is also known medically as micturition , voiding , uresis , or, rarely, emiction , and known colloquially by various names including peeing , weeing , pissing , and euphemistically number one . The process of urination
4545-418: Is under voluntary control in healthy humans and other animals , but may occur as a reflex in infants, some elderly individuals, and those with neurological injury. It is normal for adult humans to urinate up to seven times during the day. In some animals, in addition to expelling waste material, urination can mark territory or express submissiveness . Physiologically, urination involves coordination between
4646-400: The carotid sinus is pressed. A normal response to carotid sinus massage is reduction in blood pressure and slowing of the heart rate. Especially in people with hypersensitive carotid sinus syndrome this response can cause syncope or presyncope. Heart-related causes may include an abnormal heart rhythm , problems with the heart valves or heart muscle, or blockages of blood vessels from
4747-453: The central , autonomic , and somatic nervous systems . Brain centres that regulate urination include the pontine micturition center , periaqueductal gray , and the cerebral cortex . The main organs involved in urination are the urinary bladder and the urethra . The smooth muscle of the bladder, known as the detrusor , is innervated by sympathetic nervous system fibers from the lumbar spinal cord and parasympathetic fibers from
4848-407: The pontine micturition center and, like defecation , subject to voluntary facilitation and inhibition. In healthy individuals, the lower urinary tract has two discrete phases of activity: the storage (or guarding) phase, when urine is stored in the bladder; and the voiding phase, when urine is released through the urethra. The state of the reflex system is dependent on both a conscious signal from
4949-479: The sacral spinal cord. Fibers in the pelvic nerves constitute the main afferent limb of the voiding reflex; the parasympathetic fibers to the bladder that constitute the excitatory efferent limb also travel in these nerves. Part of the urethra is surrounded by the male or female external urethral sphincter , which is innervated by the somatic pudendal nerve originating in the cord, in an area termed Onuf's nucleus . Smooth muscle bundles pass on either side of
5050-550: The standing position is regarded as the more efficient option among healthy males. In restrooms without urinals, and sometimes at home, men may be urged to use the sitting position as to diminish spattering of urine. Elderly males with prostate gland enlargement may benefit from sitting down to urinate, with the seated voiding position found superior as compared with standing in elderly males with benign prostate hyperplasia . In Western culture, females usually sit or squat for urination, depending on what type of toilet they use;
5151-687: The UK, although British cultural tradition itself seems to find such practices objectionable. In Islamic toilet etiquette , it is haram to urinate while facing the Qibla , or to turn one's back to it when urinating or relieving bowels, but modesty requirements for females make it impossible for girls to relieve themselves without facilities. When toilets are unavailable, females can relieve themselves in Laos , Russia and Mongolia in emergency, but it remains less accepted for females in India even when circumstances make this
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#17328583080425252-408: The adult, the volume of urine in the bladder that normally initiates a reflex contraction is about 300–400 millilitres (11–14 imp fl oz; 10–14 US fl oz). During storage, bladder pressure stays low, because of the bladder's highly compliant nature. A plot of bladder (intravesical) pressure against the depressant of fluid in the bladder (called a cystometrogram ), will show
5353-505: The age of 80 and a third of medical students describe at least one event at some point in their lives. Of those presenting with syncope to an emergency department, about 4% died in the next 30 days. The risk of a poor outcome, however, depends very much on the underlying cause. Causes range from non-serious to potentially fatal. There are three broad categories of causes: heart or blood vessel related; reflex , also known as neurally mediated; and orthostatic hypotension . Issues with
5454-423: The bladder becomes full, afferent firing increases, yet the micturition reflex can be voluntarily inhibited until it is appropriate to begin voiding. Voiding begins when a voluntary signal is sent from the brain to begin urination, and continues until the bladder is empty. Bladder afferent signals ascend the spinal cord to the periaqueductal gray , where they project both to the pontine micturition center and to
5555-410: The bladder by inhibiting sacral parasympathetic preganglionic neurons and exciting lumbar sympathetic preganglionic neurons. Conversely, afferent input causes contraction of the sphincter through excitation of Onuf's nucleus, and contraction of the bladder neck and urethra through excitation of the sympathetic preganglionic neurons. Diuresis (production of urine by the kidney) occurs constantly, and as
5656-403: The bladder is empty. Many men, and some women, may sometimes briefly shiver after or during urination. After urination, the female urethra empties partially by gravity, with assistance from muscles. Urine remaining in the male urethra is expelled by several contractions of the bulbospongiosus muscle , and, by some men, manual squeezing along the length of the penis to expel the rest of
5757-410: The bladder is flaccid and unresponsive. It becomes overfilled, and urine dribbles through the sphincters ( overflow incontinence ). After spinal shock has passed, a spinally mediated voiding reflex ensues, although there is no voluntary control and no inhibition or facilitation from higher centers. Some paraplegic patients train themselves to initiate voiding by pinching or stroking their thighs, provoking
5858-446: The bladder is fully distended the superficial cells become squamous (flat) and the stratification of the cuboidal cells is reduced in order to provide lateral stretching. The physiology of micturition and the physiologic basis of its disorders are subjects about which there is much confusion, especially at the supraspinal level. Micturition is fundamentally a spinobulbospinal reflex facilitated and inhibited by higher brain centers such as
5959-442: The bladder wall hypertrophied. The reason for the difference between the small, hypertrophic bladder seen in this condition and the distended, hypotonic bladder seen when only the afferent nerves are interrupted is not known. The hyperactive state in the former condition suggests the development of denervation hypersensitization even though the neurons interrupted are preganglionic rather than postganglionic . During spinal shock ,
6060-420: The brain and the firing rate of sensory fibers from the bladder and urethra. At low bladder volumes, afferent firing is low, resulting in excitation of the outlet (the sphincter and urethra), and relaxation of the bladder. At high bladder volumes, afferent firing increases, causing a conscious sensation of urinary urge. Individual ready to urinate consciously initiates voiding, causing the bladder to contract and
6161-463: The brain. Aortic stenosis and mitral stenosis are the most common examples. Major valves of the heart become stiffened and reduce the efficiency of the hearts pumping action. This may not cause symptoms at rest but with exertion, the heart is unable to keep up with increased demands leading to syncope. Aortic stenosis presents with repeated episodes of syncope. Rarely, cardiac tumors such as atrial myxomas can also lead to syncope. Diseases involving
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#17328583080426262-589: The brain. The tilt-table test typically evokes the attack. Avoiding what brings on the syncope and possibly greater salt intake is often all that is needed. Associated symptoms may be felt in the minutes leading up to a vasovagal episode and are referred to as the prodrome. These consist of light-headedness, confusion, pallor, nausea, salivation, sweating, tachycardia, blurred vision, and sudden urge to defecate among other symptoms. Vasovagal syncope can be considered in two forms: Syncope has been linked with psychological triggers. This includes fainting in response to
6363-413: The brain. In all three types the bladder contracts, but the contractions are generally not sufficient to empty the viscus completely, and residual urine is left in the bladder. Paruresis , also known as shy bladder syndrome, is an example of a bladder interruption from the brain that often causes total interruption until the person has left a public area. These people (males) may have difficulty urinating in
6464-547: The cerebrum. At a certain level of afferent activity, the conscious urge to void or urination urgency , becomes difficult to ignore. Once the voluntary signal to begin voiding has been issued, neurons in the pontine micturition center fire maximally, causing excitation of sacral preganglionic neurons. The firing of these neurons causes the wall of the bladder to contract; as a result, a sudden, sharp rise in intravesical pressure occurs. The pontine micturition center also causes inhibition of Onuf's nucleus, resulting in relaxation of
6565-495: The culture of the ancient Persians and highlighting the differences with those of the Greeks , noted that to urinate in the presence of others was prohibited among Persians. There was a popular belief in the UK, that it was legal for a man to urinate in public so long as it occurred on the rear wheel of his vehicle and he had his right hand on the vehicle, but this is not true. Public urination still remains more accepted by males in
6666-418: The detrusor muscle to contract and the internal urethral sphincter to relax. The external urethral sphincter (sphincter urethrae) is under somatic control and is consciously relaxed during micturition. In infants, voiding occurs involuntarily (as a reflex). The ability to voluntarily inhibit micturition develops by the age of two–three years, as control at higher levels of the central nervous system develops. In
6767-527: The event in those with pulmonary embolism. Routine broad panel laboratory testing detects abnormalities in <2–3% of results and is therefore not recommended. Based on this initial workup many physicians will tailor testing and determine whether a person qualifies as 'high-risk', 'intermediate risk' or 'low-risk' based on risk stratification tools. More specific tests such as implantable loop recorders , tilt table testing or carotid sinus massage may be useful in uncertain cases. Computed tomography (CT)
6868-419: The event. Electrocardiogram (ECG) finds that should be looked for include signs of heart ischemia , arrhythmias , atrioventricular blocks , a long QT , a short PR , Brugada syndrome , signs of hypertrophic obstructive cardiomyopathy (HOCM), and signs of arrhythmogenic right ventricular dysplasia (ARVD/C). Signs of HCM include large voltages in the precordial leads, repolarization abnormalities, and
6969-453: The expression of ZNF804A, making this gene the strongest driver of the association. Reflex syncope or neurally mediated syncope occurs when blood vessels expand and heart rate decreases inappropriately leading to poor blood flow to the brain. This may occur from either a triggering event such as exposure to blood, pain, strong feelings, or a specific activity such as urination , vomiting , or coughing . Vasovagal (situational) syncope
7070-416: The external urinary sphincter. When the external urinary sphincter is relaxed urine is released from the urinary bladder when the pressure there is great enough to force urine to flow out of the urethra. The micturition reflex normally produces a series of contractions of the urinary bladder. The flow of urine through the urethra has an overall excitatory role in micturition, which helps sustain voiding until
7171-724: The following collapse can make a strong and dramatic impression on bystanders. Arterial disease in the upper spinal cord, or lower brain that causes syncope if there is a reduction in blood supply. This may occur with extending the neck or with use of medications to lower blood pressure. There are other conditions which may cause or resemble syncope. Seizures and syncope can be difficult to differentiate. Both often present as sudden loss of consciousness and convulsive movements may be present or absent in either. Movements in syncope are typically brief and more irregular than seizures. Akinetic seizures can present with sudden loss of postural tone without associated tonic-clonic movements. Absence of
7272-669: The gender differences. Much of this pathway was discovered in animal experiments by Bezold (Vienna) in the 1860s. In animals, it may represent a defense mechanism when confronted by danger ("playing possum"). A 2023 study identified neuropeptide Y receptor Y2 vagal sensory neurons (NPY2R VSNs) and the periventricular zone (PVZ) as a coordinated neural network participating in the cardioinhibitory Bezold–Jarisch reflex (BJR) regulating fainting and recovery. Syncope may be caused by specific behaviors including coughing, urination, defecation, vomiting, swallowing ( deglutition ), and following exercise. Manisty et al. note: "Deglutition syncope
7373-402: The heart . A hemoglobin count may indicate anemia or blood loss. However, this has been useful in only about 5% of people evaluated for fainting. The tilt table test is performed to elicit orthostatic syncope secondary to autonomic dysfunction (neurogenic). A number of factors make a heart related cause more likely including age over 35, prior atrial fibrillation , and turning blue during
7474-474: The heart and blood vessels are the cause in about 10% and typically the most serious while neurally mediated is the most common. There also seems to be a genetic component to syncope. A recent genetic study has identified first risk locus for syncope and collapse. The lead genetic variant, residing at chromosome 2q31.1, is an intergenic variant approximately 250 kb downstream of the ZNF804A gene. The variant affected
7575-399: The heat, may lead to decreased blood flow to the brain. Closely related to other causes of syncope related to hypotension (low blood pressure) such as orthostatic syncope. Some psychological conditions ( anxiety disorder, somatic symptom disorder , conversion disorder ) may cause symptoms resembling syncope. A number of psychological interventions are available. Low blood sugar can be
7676-422: The intrinsic response of the smooth muscle to stretch. When the afferent and efferent nerves are both destroyed, as they may be by tumors of the cauda equina or filum terminale , the bladder is flaccid and distended for a while. Gradually, however, the muscle of the "decentralized bladder" becomes active, with many contraction waves that expel dribbles of urine out of the urethra. The bladder becomes shrunken and
7777-441: The legs causes most people to sit or lie down if there is time to do so. This may avert a complete collapse, but whether the patient sits down or falls down, the result of an ischaemic episode is a posture in which less blood pressure is required to achieve adequate blood flow. An individual with very little skin pigmentation may appear to have all color drained from his or her face at the onset of an episode. This effect combined with
7878-435: The loss of consciousness such as lightheadedness , sweating , pale skin , blurred vision, nausea, vomiting, or feeling warm. Syncope may also be associated with a short episode of muscle twitching. Psychiatric causes can also be determined when a patient experiences fear, anxiety, or panic; particularly before a stressful event, usually medical in nature. When consciousness and muscle strength are not completely lost, it
7979-415: The muscles of the pelvic floor causes a sufficient downward tug on the detrusor muscle to initiate its contraction. Another possibility is the excitation or disinhibition of neurons in the pontine micturition center, which causes concurrent contraction of the bladder and relaxation of the sphincter. There is an inhibitory area for micturition in the midbrain. After transection of the brain stem just above
8080-511: The neural activity associated with a full bladder comes from the bladder itself, and can be felt there as well. In females the need to urinate is felt in the lower abdomen region when the bladder is full. When the bladder becomes too full, the sphincter muscles will involuntarily relax, allowing urine to pass from the bladder. Release of urine is experienced as a lessening of the discomfort. Many clinical conditions can cause disturbances to normal urination, including: A drug that increases urination
8181-399: The operating room. There is also evidence that exercise training can help reduce orthostatic intolerance. More serious orthostatic hypotension is often the result of certain commonly prescribed medications such as diuretics, β-adrenergic blockers, other anti-hypertensives (including vasodilators), and nitroglycerin . In a small percentage of cases, the cause of orthostatic hypotensive faints
8282-451: The outlet to relax. Voiding continues until the bladder empties completely, at which point the bladder relaxes and the outlet contracts to re-initiate storage. 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. During micturition, parasympathetic stimulation causes
8383-426: The person will experience reflex tachycardia (at least 20% increased over supine) and a drop in blood pressure. Hypoadrenergic orthostatic hypotension occurs when the person is unable to sustain a normal sympathetic response to blood pressure changes during movement despite adequate intravascular volume. There is little to no compensatory increase in heart rate or blood pressure when standing for up to 10 minutes. This
8484-512: The pons, the threshold is lowered and less bladder filling is required to trigger it, whereas after transection at the top of the midbrain, the threshold for the reflex is essentially normal. There is another facilitatory area in the posterior hypothalamus. In humans with lesions in the superior frontal gyrus, the desire to urinate is reduced and there is also difficulty in stopping micturition once it has commenced. However, stimulation experiments in animals indicate that other cortical areas also affect
8585-527: The presence of others and will consequently avoid using urinals without dividers or those directly adjacent to another person. Alternatively, they may opt for the privacy of a stall or simply avoid public toilets altogether. When the sacral dorsal roots are cut in experimental animals or interrupted by diseases of the dorsal roots such as tabes dorsalis in humans, all reflex contractions of the bladder are abolished. The bladder becomes distended, thin-walled, and hypotonic, but there are some contractions because of
8686-453: The process. The bladder can be made to contract by voluntary facilitation of the spinal voiding reflex when it contains only a few milliliters of urine. Voluntary contraction of the abdominal muscles aids the expulsion of urine by increasing the pressure applied to the urinary bladder wall, but voiding can be initiated without straining even when the bladder is nearly empty. Voiding can also be consciously interrupted once it has begun, through
8787-436: The risk of syncope. Brugada syndrome also commonly presents with syncope secondary to arrhythmia. Typically, tachycardic-generated syncope is caused by a cessation of beats following a tachycardic episode. This condition, called tachycardia-bradycardia syndrome, is usually caused by sinoatrial node dysfunction or block or atrioventricular block . Blockages in major vessels or within the heart can also impede blood flow to
8888-407: The same term [REDACTED] This disambiguation page lists articles associated with the title Faint . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Faint&oldid=1215480865 " Category : Disambiguation pages Hidden categories: Short description
8989-579: The sanitary facilities available. While sitting toilets are the most common form in Western countries, squat toilets are common in Asia , Africa , and the Arab world . Urinals for men are widespread worldwide, although women's urinals are available in some countries, recently becoming more common in Western countries. With the spread of pants among women, a standing posture became impractical, but in some regions where women wear traditional skirts or robes, an upright posture
9090-411: The shape and strength of the heart can be a cause of reduced blood flow to the brain, which increases risk for syncope. The most common cause in this category is fainting associated with an acute myocardial infarction or ischemic event. The faint in this case is primarily caused by an abnormal nervous system reaction similar to the reflex faints. Women are significantly more likely to experience syncope as
9191-402: The sight or thought of blood, needles, pain, and other emotionally stressful situations. One theory in evolutionary psychology is that fainting at the sight of blood might have evolved as a form of playing dead which increased survival from attackers and might have slowed blood loss in a primitive environment. "Blood-injury phobia", as this is called, is experienced by about 15% of people. It
9292-495: The space toilet also has a receptacle for defecation. A puer mingens is a figure in a work of art depicted as a prepubescent boy in the act of urinating, either actual or simulated. The puer mingens could represent anything from whimsy and boyish innocence to erotic symbols of virility and masculine bravado. Babies have little socialized control over urination within traditions or families that do not practice elimination communication and instead use diapers . Toilet training
9393-442: The thighs, above the ground, facing outward, in order to urinate. The fetus urinates hourly and produces most of the amniotic fluid in the second and third trimester of pregnancy. The amniotic fluid is then recycled by fetal swallowing. Occasionally, if a male's penis is damaged or removed, or a female's genitals /urinary tract is damaged, other urination techniques must be used. Most often in such cases, doctors will reposition
9494-410: The underlying cause. Those who are considered at high risk following investigation may be admitted to hospital for further monitoring of the heart . Syncope affects about three to six out of every thousand people each year. It is more common in older people and females. It is the reason for one to three percent of visits to emergency departments and admissions to hospital. Up to half of women over
9595-412: The urethra to a location where urination can still be accomplished, usually in a position that would promote urination only while seated/squatting, though a permanent urinary catheter may be used in rare cases. Sometimes urination is done in a container such as a bottle, urinal , bedpan, or chamber pot (also known as a gazunder ). A container or wearable urine collection device may be used so that
9696-456: The urethra, and these fibers are sometimes called the internal urethral sphincter , although they do not encircle the urethra. Further along the urethra is a sphincter of skeletal muscle, the sphincter of the membranous urethra (external urethral sphincter). The bladder's epithelium is termed transitional epithelium which contains a superficial layer of dome-like cells and multiple layers of stratified cuboidal cells underneath when evacuated. When
9797-421: The urine can be examined for medical reasons or for a drug test , for a bedridden patient, when no toilet is available, or there is no other possibility to dispose of the urine immediately. An alternative solution (for traveling, stakeouts , etc.) is a special disposable bag containing absorbent material that solidifies the urine within seconds, making it convenient and safe to store and dispose of later. It
9898-443: The urine. For land mammals over 1 kilogram, the duration of urination does not vary with body mass, being dispersed around an average of 21 seconds (standard deviation 13 seconds), despite a 4 order of magnitude (1000×) difference in bladder volume. This is due to increased urethra length of large animals, which amplifies gravitational force (hence flow rate), and increased urethra width, which increases flow rate. For smaller mammals
9999-525: The ventricles. VT causes syncope and can result in sudden death. Ventricular tachycardia, which describes a heart rate of over 100 beats per minute with at least three irregular heartbeats as a sequence of consecutive premature beats, can degenerate into ventricular fibrillation , which is rapidly fatal without cardiopulmonary resuscitation (CPR) and defibrillation . Long QT syndrome can cause syncope when it sets off ventricular tachycardia or torsades de pointes . The degree of QT prolongation determines
10100-520: The vertebral artery or the internal thoracic artery, due to a proximal stenosis (narrowing) and/or occlusion of the subclavian artery. Symptoms such as syncope, lightheadedness, and paresthesias occur while exercising the arm on the affected side (most commonly the left). Aortic dissection (a tear in the aorta) and cardiomyopathy can also result in syncope. Various medications, such as beta blockers , may cause bradycardia induced syncope. A pulmonary embolism can cause obstructed blood vessels and
10201-456: The walls of vessels in the carotid sinus and aortic arch. These receptors then trigger a sympathetic nervous response to compensate and redistribute blood back into the brain. The sympathetic response causes peripheral vasoconstriction and increased heart rate. These together act to raise blood pressure back to baseline. Apparently healthy individuals may experience minor symptoms ("lightheadedness", "greying-out") as they stand up if blood pressure
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