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How do gory images lead to nausea?
Yesterday my friend visited shock sites (a website). He said that he got nauseous sensation within seconds after viewing the gory images. However, I don't understand how seeing such sights can lead to nausea? Eyes are present at the top of the head and the digestive tract is present below the mouth. They aren't physically connected.
The connection between eyes and food pipe had to do nothing with the motion sickness because the visual inputs and outputs to these sensory information are processed in the brain itself, So there is not need for eyes and food pipe to be connected together in order to cause nausea.
Vasovagal response or vasovagal response or vasovagal attack (also called neurocardiogenic syncope) is a malaise mediated by the vagus nerve. When it leads to syncope or "fainting", it is called a vasovagal syncope, which is the most common type of fainting.
This case is most commonly seen in adults and adolescents. There are several syndromes which comes under the vasovagal syncope which consists of symptoms like loss of consiusness,lightheadness,nausea,sweating,tinnitus,confusion,altered heart rate,fuzzy thoughts,cloud like spots in vision etc.
Vasovagal syncope occurs in response to a trigger, with a corresponding malfunction in the parts of the nervous system that regulate heart rate and blood pressure. When heart rate slows, blood pressure drops, and the resulting lack of blood to the brain causes fainting and confusion.
Several pshychiatric disorders can cause vasovagal response like,
When it comes to seeing red, the faint feelings could be tied to a phenomenon called blood-injury phobia. According to WebMD, this condition evolved as a way for humans to cope with threats:
"The idea is that back in time, when someone was coming at someone else with a sharp stick or rock, a kind of genetic variation allowed certain people to faint in response," explains Tyler C. Ralston, PsyD, a clinical psychologist in Honolulu, who treats people with blood-injury phobias. Warriors who fainted looked dead and were passed over during battle. The blood pressure drop also might have helped those who were wounded avoid bleeding to death. Survivors then passed on the "fainting" gene.
"Overcoming Obstacles in CBT" written by Yvonne Tone and Michael McDonough states a condition about a patient having similar psychological problem described in the question. Here the patient's panic is associated with "gory images" of injury or illness, and his responses included intense nausea, pale skin, sweat and sometime fainting. He also reports avoiding gory scenes on TV/filim and medical programmes. The problem is identified as co-morbid panic/agoraphobia and blood injury phobia. http://books.google.co.in/books?id=1uIYqkKgKRYC&pg=PA44&dq=nausea+and+gory+images&hl=en&sa=X&ei=qLZ2VJPMJ420uAS8qoHIBA&ved=0CB0Q6AEwAA#v=onepage&q=nausea%20and%20gory%20images&f=false
The connection is almost certainly psychological. For me, I can watch Grey's Anatomy, Spartacus, or any number of bloody shows while eating, but while researching microsurgery I came across an image of a hand cut in half and it bothered me for an entire day. Therefore, for me at least (and likely others) nausea from gore is context dependent and therefore likely psychological.
Then again, there may be some biological basis. From https://en.wikipedia.org/wiki/Disgust#Neural_basis :
Functional MRI experiments have revealed that the anterior insula in the brain is particularly active when experiencing disgust, when being exposed to offensive tastes, and when viewing facial expressions of disgust.
That Wikipedia article links to this Letter to Nature: http://www.nature.com/nature/journal/v389/n6650/full/389495a0.html which provides more detail.
Also, the part of the brain that actually controls vomiting is called the Area postrema.
So… in short, my answer is "The insular cortex of the brain is responsible, though there is a large psychological component."
Air pollution consists of chemicals or particles in the air that can harm the health of humans, animals, and plants. It also damages buildings.
Biology, Ecology, Earth Science, Geography
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Air pollution consists of chemicals or particles in the air that can harm the health of humans, animals, and plants. It also damages buildings. Pollutants in the air take many forms. They can be gases, solid particles, or liquid droplets.
Sources of Air Pollution
Pollution enters the Earth's atmosphere in many different ways. Most air pollution is created by people, taking the form of emissions from factories, cars, planes, or aerosol cans. Second-hand cigarette smoke is also considered air pollution. These man-made sources of pollution are called anthropogenic sources.
Some types of air pollution, such as smoke from wildfires or ash from volcanoes, occur naturally. These are called natural sources.
Air pollution is most common in large cities where emissions from many different sources are concentrated. Sometimes, mountains or tall buildings prevent air pollution from spreading out. This air pollution often appears as a cloud making the air murky. It is called smog. The word "smog" comes from combining the words "smoke" and "fog."
Large cities in poor and developing nations tend to have more air pollution than cities in developed nations. According to the World Health Organization (WHO), some of the worlds most polluted cities are Karachi, Pakistan New Delhi, India Beijing, China Lima, Peru and Cairo, Egypt. However, many developed nations also have air pollution problems. Los Angeles, California, is nicknamed Smog City.
Indoor Air Pollution
Air pollution is usually thought of as smoke from large factories or exhaust from vehicles. But there are many types of indoor air pollution as well.
Heating a house by burning substances such as kerosene, wood, and coal can contaminate the air inside the house. Ash and smoke make breathing difficult, and they can stick to walls, food, and clothing.
Naturally-occurring radon gas, a cancer-causing material, can also build up in homes. Radon is released through the surface of the Earth. Inexpensive systems installed by professionals can reduce radon levels.
Some construction materials, including insulation, are also dangerous to people's health. In addition, ventilation, or air movement, in homes and rooms can lead to the spread of toxic mold. A single colony of mold may exist in a damp, cool place in a house, such as between walls. The mold's spores enter the air and spread throughout the house. People can become sick from breathing in the spores.
Effects On Humans
People experience a wide range of health effects from being exposed to air pollution. Effects can be broken down into short-term effects and long-term effects.
Short-term effects, which are temporary, include illnesses such as pneumonia or bronchitis. They also include discomfort such as irritation to the nose, throat, eyes, or skin. Air pollution can also cause headaches, dizziness, and nausea. Bad smells made by factories, garbage, or sewer systems are considered air pollution, too. These odors are less serious but still unpleasant.
Long-term effects of air pollution can last for years or for an entire lifetime. They can even lead to a person's death. Long-term health effects from air pollution include heart disease, lung cancer, and respiratory diseases such as emphysema. Air pollution can also cause long-term damage to people's nerves, brain, kidneys, liver, and other organs. Some scientists suspect air pollutants cause birth defects. Nearly 2.5 million people die worldwide each year from the effects of outdoor or indoor air pollution.
People react differently to different types of air pollution. Young children and older adults, whose immune systems tend to be weaker, are often more sensitive to pollution. Conditions such as asthma, heart disease, and lung disease can be made worse by exposure to air pollution. The length of exposure and amount and type of pollutants are also factors.
Effects On The Environment
Like people, animals, and plants, entire ecosystems can suffer effects from air pollution. Haze, like smog, is a visible type of air pollution that obscures shapes and colors. Hazy air pollution can even muffle sounds.
Air pollution particles eventually fall back to Earth. Air pollution can directly contaminate the surface of bodies of water and soil. This can kill crops or reduce their yield. It can kill young trees and other plants.
Sulfur dioxide and nitrogen oxide particles in the air, can create acid rain when they mix with water and oxygen in the atmosphere. These air pollutants come mostly from coal-fired power plants and motor vehicles. When acid rain falls to Earth, it damages plants by changing soil composition degrades water quality in rivers, lakes and streams damages crops and can cause buildings and monuments to decay.
Like humans, animals can suffer health effects from exposure to air pollution. Birth defects, diseases, and lower reproductive rates have all been attributed to air pollution.
Global warming is an environmental phenomenon caused by natural and anthropogenic air pollution. It refers to rising air and ocean temperatures around the world. This temperature rise is at least partially caused by an increase in the amount of greenhouse gases in the atmosphere. Greenhouse gases trap heat energy in the Earths atmosphere. (Usually, more of Earths heat escapes into space.)
Carbon dioxide is a greenhouse gas that has had the biggest effect on global warming. Carbon dioxide is emitted into the atmosphere by burning fossil fuels (coal, gasoline, and natural gas). Humans have come to rely on fossil fuels to power cars and planes, heat homes, and run factories. Doing these things pollutes the air with carbon dioxide.
Other greenhouse gases emitted by natural and artificial sources also include methane, nitrous oxide, and fluorinated gases. Methane is a major emission from coal plants and agricultural processes. Nitrous oxide is a common emission from industrial factories, agriculture, and the burning of fossil fuels in cars. Fluorinated gases, such as hydrofluorocarbons, are emitted by industry. Fluorinated gases are often used instead of gases such as chlorofluorocarbons (CFCs). CFCs have been outlawed in many places because they deplete the ozone layer.
Worldwide, many countries have taken steps to reduce or limit greenhouse gas emissions to combat global warming. The Kyoto Protocol, first adopted in Kyoto, Japan, in 1997, is an agreement between 183 countries that they will work to reduce their carbon dioxide emissions. The United States has not signed that treaty.
In addition to the international Kyoto Protocol, most developed nations have adopted laws to regulate emissions and reduce air pollution. In the United States, debate is under way about a system called cap and trade to limit emissions. This system would cap, or place a limit, on the amount of pollution a company is allowed. Companies that exceeded their cap would have to pay. Companies that polluted less than their cap could trade or sell their remaining pollution allowance to other companies. Cap and trade would essentially pay companies to limit pollution.
In 2006 the World Health Organization issued new Air Quality Guidelines. The WHOs guidelines are tougher than most individual countries existing guidelines. The WHO guidelines aim to reduce air pollution-related deaths by 15 percent a year.
Anybody can take steps to reduce air pollution. Millions of people every day make simple changes in their lives to do this. Taking public transportation instead of driving a car, or riding a bike instead of traveling in carbon dioxide-emitting vehicles are a couple of ways to reduce air pollution. Avoiding aerosol cans, recycling yard trimmings instead of burning them, and not smoking cigarettes are others.
Photograph by Trudy Muegel, MyShot
The United States conducted tests of nuclear weapons at the Nevada Test Site in southern Nevada in the 1950s. These tests sent invisible radioactive particles into the atmosphere. These air pollution particles traveled with wind currents, eventually falling to Earth, sometimes hundreds of miles away in states including Idaho, Utah, Arizona, and Washington. These areas were considered to be "downwind" from the Nevada Test Site.
Decades later, people living in those downwind areascalled "downwinders"began developing cancer at above-normal rates. In 1990, the U.S. government passed the Radiation Exposure Compensation Act. This law entitles some downwinders to payments of $50,000.
What has come to be known as the London Smog of 1952, or the Great Smog of 1952, was a four-day incident that sickened 100,000 people and caused as many as 12,000 deaths. Very cold weather in December 1952 led residents of London, England, to burn more coal to keep warm. Smoke and other pollutants became trapped by a thick fog that settled over the city. The polluted fog became so thick that people could only see a few meters in front of them.
There are five major greenhouse gases in Earth's atmosphere.
How do gory images lead to nausea? - Biology
Do you get squeamish at the site of blood and guts? Does your stomach turn on seeing rotten food riddled with maggots? Visceral responses to disgusting sights are common, but the secret of how we experience such repulsion has long left scientists scratching their heads.
However, a new study by Cambridge University researchers reveals the key to disgust is quite literally all about our "gut instinct" – by paying participants to stare at horrendous images, scientists have found that we look away from revolting sights not because of our brains, but because of the changes in our stomach's rhythm.
And now, thanks to the research and a fairly common anti-nausea drug, they have found how to allow humans to look at disgusting sights for longer. Why would anyone want to do this?
As Cambridge researcher Edwin Dalmaijer tells CGTN Europe, the discovery could have an important real-world impact for treating people struggling with psychopathologies such as obsessive compulsive disorder (OCD). Beyond the clinic, the findings are already giving us a deep insight into the mysterious power of the body over the brain.
Settling the stomach
The key to the study carried out at Cambridge's MRC Cognition and Brain Sciences Unit was getting people used to disgusting sights through the use of the anti-nausea drug domperidone.
"One of my co-authors, Camilla North, knew of this brilliant drug that is essentially something that settles your stomach," says Dalmaijer. "The idea is that this specific drug really only works on the gut, it doesn't really work on the brain."
Domperidone works by stabilizing the rhythm of the electrical signals in our stomach muscles. These signals that usually help the stomach contract and expand to ensure food moves through our digestive tracts. However, they become abnormal when we are nauseous, and when the rhythms are heavily disrupted – for example, when we see something particularly disgusting – it can lead to our stomachs quite literally turning.
Humans rarely habituate to the sensation of disgust and the reason is linked to changes in the stomach's rhythm. /CFP
"There are core disgust components," explains Dalmaijer: "They include things like feces, vomit, basically anything that if you encounter it, you probably want to avoid it because these tend to be the things that . potentially make you ill."
The other prevalent core disgust is what the researcher describes as gore, things like blood and organs that shouldn't be on the outside. As the researcher explains, when see something disgusting, "you won't necessarily feel it, but we can measure it in your stomach."
"We were hoping that, because of that settling of the gut [via the drug], maybe the approach to these disgusting images would also potentially be altered," says Dalmaijer, and that's indeed what the researchers discovered.
The study was carried out in five different stages to test the effect of domperidone on habituating disgust. /Cambridge MRC Cognition and Brain Sciences Unit
Testing ad nauseum
The 25 volunteers, aged between 18 and 35, were put into to two groups: one group to take domperidone, the second a placebo. Before administering the tablets, Dalmaijer and his colleagues showed both groups a selection of neutral images – pictures of things including scarves and buttons – alongside ones picked specifically to trigger innate disgust responses.
As they looked, the researchers tracked their eye movements to see on which image – neutral or disgusting – they lingered. Without encouragement, participants naturally looked away from the unpleasant ones.
Thirty minutes after taking their tablets, the participants were shown the images again. The researchers discovered that initially, taking domperidone had little effect on the time spent looking at a particular image, which Dalmaijer chalks up to the fact people don't really habituate to disgust: "I can show you the same picture of a particularly disgusting image and you'll just try to avoid it and you'll continue to do so, even though you've seen it countless times over and over and over."
And as Tim Dalgleish, also from the MRC Unit explains: "Just using the drug itself isn't enough: overcoming disgust avoidance requires us to be motivated or incentivized."
Volunteers were shown a selection of neutral images – pictures of things including scarves and buttons – alongside ones picked specifically to trigger innate disgust responses. /Cambridge MRC Cognition and Brain Sciences Unit
Paid to look
Next, the researchers gave the volunteers an incentive: for every four to eight seconds that they looked at a revolting image, they would get 35 cents – and hear a "kerching!" sound. The volunteers then viewed the images for a final time, but this time with no incentive.
As was to be expected, the dwell time went up dramatically when they were paid to look, but Dalmaijer explains that "paying people to look at poo doesn't actually help them at all."
Adding: "They look at the disgusting images while you pay them and immediately flip back to normal behavior directly when the payment stops."
However, in the final round – when the volunteers were no longer being incentivized – the team discovered those who had received domperidone spent much longer than the placebo group looking at the disgusting images.
Volunteers who took domperidone looked at the disgusting pictures far longer than those who took the placebo. /Cambridge MRC Cognition and Brain Sciences Unit
Those on the placebo looked at the neutral image around 5.5 seconds longer than the disgusting one, but with domperidone, the difference was only roughly 2.5 seconds.
"We've known for some time that when you see something disgusting, your stomach muscles' electrical signals become dysregulated," said Camilla Nord, Dalmaijer's colleague, "which in some cases causes people to feel sick or their stomach to turn. You're then likely to avoid that thing.
"What we've shown here is that when we steady the stomach's electrical signals, people become less avoidant of a disgusting image after engaging with it. Changes in the stomach's rhythm led to reduced disgust avoidance in our study – and so the stomach's rhythm must be one cause of disgust avoidance in general."
Psychopathologies such as arachnophobia and post-traumatic stress disorder can also be similarly rooted in our disgust reflex. /CFP
Disgust as treatment
While Dalmaijer admits "paying people to look at poo" may seem "inherently silly," he underscores the importance of the findings to treating a wide range of anxiety disorders.
"The clearest example would be obsessive compulsive disorder, he says: "Where in some people, they develop compulsions to do a lot of cleaning and they can be driven by a fear of disgusting things."
Psychopathologies such as arachnophobia (the fear of spiders) and post-traumatic stress disorder (PTSD) can also be similarly rooted in our disgust reflex, he explains: "Sometimes people have really particularly gory experiences and they can leave a really big mark on them and that can form into PTSD.
"To get over that initial traumatic experience that was really rather disgusting, this can potentially also help to chip away at that central disgust that is core to these psychopathologies."
One of the main problems with treating such patients has been the lack of habituation to disgusting sights. "This is one reason why treating pathological disgust by exposure is often unsuccessful," he says. "Our research suggests domperidone may help."
Edwin Dalmaijer says moral disgust around things such as eating insects – a common practice in many places in the world – might be linked to stomach responses. /CFP
The question is whether such treatment would work for more moral understandings of repulsion. "We have all sorts of more fanciful disgusts," says Dalmaijer. "Where you might hear someone say, 'Oh, what an absolutely disgusting idea by the politician to ban immigrants or allow gay marriage.'"
Whether metaphorical disgust actually triggers similar reactions to things like feces and gore is unclear. "In science we try to kind of define our words a bit more narrowly," he says. "But they might."
He adds: "Specifically things like eating insects, which is really common in some parts of the world and can elicit a disgust-like response in other parts of the world – those things might be a bit more linked to stomach responses."
And with relatively little research on the topic, Dalmaijer says he's dying to delve into the topic further: "That's on the top of the list of stuff that I'm going to do next."
Whatever the outcome, by proving our reactions to unpleasant sights are based in our stomachs, not our brains, the researchers have gone a long way to unpicking the powerful relationship between our body and our behavior.
"We have this strong tendency of thinking the brain, the mind, this is where all of our things are regulated and the body is just a puppet that listens to the brain," says Dalmaijer.
"This [study] is a really positive example of how sometimes the state of your body can impact your thinking," he adds. "And that's just a really neat little thing."
What Causes Ulcerative Colitis?
The exact cause isn't clear. But researchers think your immune system -- which defends you from germs -- is involved. When you have UC, your immune system may not react like it should to bacteria in your digestive tract. Doctors aren't sure whether this triggers the condition or results from it. Stress and your diet can make your symptoms worse, but they don't cause ulcerative colitis.
Nausea and Vomiting (Emesis)
Vomiting can also be referred to as emesis, and consists of the following stages:
Nausea is an unpleasant sensation of wanting to vomit, and is often associated with cold sweat, pallor, salivation, loss of gastric tone, duodenal contraction, and the reflux of intestinal contents into the stomach. Nausea generally precedes vomiting, but can occur by itself. The system that brings about the loss of gastric tone, of gastric relaxation, is the efferent part of the long loop intestinal reflex that relaxes the gut during food intake.
Retching is a strong involuntary effort to vomit, and usually follows nausea. During retching, the abdominal muscles, chest wall and diaphragm all contract without any expulsion of gastric contents.
Vomiting is the forceful expulsion of the contents of the gastrointestinal system out through the mouth. From an evolutionary perspective, it is thought to have evolved as a defense mechanism of the body, serving a protective function to rid the body of noxious substances that have been ingested, rather than allowing them to be retained and absorbed by the intestine.
Contrary to popular belief, the stomach itself does not actively expel its contents during vomiting. The stomach, oesophagus, and their relevant sphincters are all in fact relaxed during vomiting. Most of the force that expels the contents arises from the contraction of the diaphragm, which is the major respiratory muscle, and the abdominal muscles, which are the muscles involved in active expiration.
Symptoms of emesis
The symptoms of emesis include:
- Profuse salivation
- Elevated heart rate
- Nausea and
- Retching movements.
Causes of nausea and vomiting
The following table highlights the major and most common causes of nausea and vomiting:
- Bowel obstructions
- Liver problems .
- Viral labyrinthitis
- Food poisoning.
- Haemorrhage. Vomiting following a head injury is considered dangerous as it indicates swelling or bleeding within the cranial cavity
- Lesions in parts of the brain.
- High blood sugar levels in diabetics
- Higher than normal blood calcium levels.
- Cancer chemotherapy (e.g. morphine, codeine)
- Immunotherapy excess.
- Severe pain.
- Psychogenic stimuli (e.g. nauseating sights and odours, high levels of stress and anxiety).
- Stimulation of the back of the throat. In some people, this can even include the presence of a tongue depressor or dental instrument.
Mechanisms of emesis
The mechanisms of emesis can be divided into three components:
- inputs go to the central nervous system (CNS), relaying the signals of emetic stimuli
- These signals are received, recognised, and centrally processed. They then form integrated emetic efferent signals coming from the CNS
- These motor and chemical efferent pathways relay signals that lead to the coordinated respiratory, gastrointestinal and abdominal muscle expulsive actions of vomiting.
Central nervous system control
There are two medullary centres of vomiting in the brain known as the sensory “chemoreceptor trigger zone (CTZ)” and the integrative centre.
Chemoreceptor trigger zone (CTZ)
The CTZ is located in the medulla of the brain. It has a defensive blood-brain barrier for detecting circulating toxins in the blood and cerebrospinal fluid (CSF), and is sensitive to a number of circulating emetic agents, including morphine, intravenous copper sulphate, and certain circulating metabolic emetic agents associated with uraemia, infections and radiation. When activated, the CTZ does not initiate vomiting itself, but relays stimuli to the integrative vomiting centre which produces the actual act of emesis.
Integrative vomiting centre
The integrative vomiting centre coordinates activities of the nearby neural structures to produce a complex patterned response, resulting in the processing and action of the vomiting reflex. The centre is located in the medulla. The motor component of the vomiting centre is controlled by both somatic and autonomic systems, meaning that both voluntary and involuntary systems are involved in the process. Their inputs are coordinated by the vomiting centre.
Somatic efferent pathways control respiratory and abdominal musculature, and visceral efferent components mediating changes in gastric tone and motility, while salivation, pallor and sweating are autonomic epiphenomena. The autonomic nervous system is not essential for the mechanical act of vomiting, but the activation of efferent nerves of the abdominal organs in the emetic process is proportional to the duration and intensity of the nausea that accompanies the process.
The vomiting centre is predominantly activated by three different mechanisms:
- By nervous impulses from the stomach, intestinal tract, and other portions of the body, resulting in a reflexive activation
- By stimulation from the higher brain centres
- By the chemoreceptor trigger zone (CTZ) sending impulses.
Afferent impulses may also arise from other sites, such as unpleasant sights and odours, as well as severe parietal pain. The most common afferent pathways are in the viscera, or abdominal organs. Vomiting can be provoked by occlusion of the coronary vessels, distension of the intestine, and irritation of the gastrointestinal mucosa. In the gastrointestinal tract, mechanoreceptors in the intestinal wall are activated by abnormal contractions, distension or physical damage. Potentially harmful chemical stimuli can also activate chemoreceptors located in the intestinal wall. These receptors then release information to the vomiting centre.
The neural pathways involved in the motor act of vomiting are associated mainly with the phrenic nerve to the diaphragm, the spinal nerves to the abdominal and intercostal muscles, efferent visceral autonomic fibres to the gut, and the viscera efferent fibres to parts of the voluntary muscles of the pharynx and larynx. The vomiting reflex is mediated by both the autonomic and somatic systems, and consists of two phases:
- Prodomal phase (pre-ejection): Relaxation of gastric muscles followed by small intestinal retrograde peristalsis
- Ejection phase: Comprises of retching and vomiting including expulsion of gastric contents.
Stimuli for vomiting
Pain, sight, smell, taste, emotion
The experience of these sensations leads to information sent to the higher centres in the brain, and then information relayed to the vomiting centre and CTZ via chemicals that transmit information to the brain, hence the name ‘neurotransmitters‘. The one that is most commonly responsible is acetylcholine, or Ach. Neurotransmitters stimulate and activate the vomiting reflex through the afferent pathways previously described.
Motion sickness is due to labyrinth stimulation. The labyrinth is a part of the inner ear involved in balance and perception of movement. Labyrinth stimulation leads to impulses passing along the vestibular nerve to the central nervous system, where it activates the CTZ to produce emesis. Neurotransmitters such as histamine or Ach are also released to the CTZ, which itself can releases chemicals such as dopamine and serotonin (5HT) that go on to stimulate the vomiting centre, which releases Ach, which then leads to the feelings of nausea and actions of vomiting.
Opioids such as codeine, morphine, pethidine, fentanyl, methadone, oxycodon, and tramadol can cause nausea and vomiting through a number of different possible mechanisms such as stimulation of CTZ, increased vestibular sensitivity, gastric stasis, or impaired intestinal motility and constipation.
Cytotoxic drugs cause stimulation of 5-HT3-receptors peripherally and possibly centrally on the CTZ. This in turn will cause the release of the aforementioned chemical transmitters dopamine and 5HT, which trigger the vomiting centre and cause the release of Ach, thereby leading to induction of nausea and vomiting. Chemotherapy-induced nausea and vomiting can affect the quality of life and result in dehydration, weight loss and malnutrition.
There are three types of emesis following cytotoxic chemotherapy:
- Acute emesis: symptoms occurring within the first 24 hours after chemotherapy
- Delayed emesis: symptoms occurring after 24-48 hours after last dose of chemotherapy
- Anticipatory emesis: a conditioned response in patients who have developed significant chemotherapy-induced nausea and vomiting during previous cycle of therapy.
Delayed emesis as well as acute emesis is a particular problem with high-dose of cisplatin and other agents such as doxorubicin. However, in up to 75% of patients, this can be prevented or alleviated by using correct anti-nausea and anti-vomiting drugs, known as anti-emetics.
Generally, for management of chemotherapy-induced nausea and vomiting a combination of anti-emetic drugs is used. For instance, dopamine antagonists, such as metoclopramide (Maxolon), and serotonin antagonists, such as palonosetron (Aloxi) and granisetron (Kytril), are used together with a corticosteroid, such as dexamethasone, to match the strengths of chemotherapy agents.
In up to 75% of patients, this can be completely prevented by using correct anti-nausea and anti-vomiting drugs, known as anti-emetics. Nausea and vomiting are particular problems with some agents such as doxorubicin and others that contain platinum. Usually a combination of anti-emetic drugs is used. For example, metoclopramide and serotonin antagonists are used in combination with a steroid to match the strengths of chemotherapy agents.
Whether radiation therapy causes nausea and vomiting depends on the part of the body being treated, the amount of radiation given, and how often the treatment is given.
When the area of the body being treated includes a large part of the abdomen, specifically, the small intestine (or small bowel), there is a greater chance of nausea and vomiting occurring. About 50% of the people with cancer who receive standard doses (180 to 200 centiGray) of radiation to their abdomen will have nausea and vomiting. These symptoms can occur 1 to 2 hours after treatment and can last for several hours.
Of those being treated with total body radiation therapy, used in bone marrow transplants, about 60% to 90% will develop nausea and vomiting if not given medicines to prevent nausea and vomiting. These people may also receive high doses of chemotherapy to prepare for the transplant.
The combination of radiation therapy and chemotherapy increases the chance of nausea and vomiting. People who receive one large dose of radiation therapy have a greater chance of nausea and vomiting than those who receive radiation therapy in smaller doses.
Hormonal changes during pregnancy
Symptoms of nausea and vomiting are common during the first trimester of the stages of pregnancy. The exact mechanisms of pregnancy-induced nausea and vomiting still is not clear, however it is thought that elevated level of pregnancy hormones can play a role in inducing nausea and vomiting. Adequate hydration should be advised. Dietary modification such as small, frequent, high-carbohydrate, low-fat meals may help.
|For more information, see Nausea and Vomiting in Pregnancy.|
Post-operative nausea and vomiting (PONV)
PONV is a result of several potential factors such as:
- The types of anaesthetic agents used such as inhaled gases and/or medications, such as morphine
- The type and the site of operation such as operations around the ear and inner ear, eyes, mouth and some abdominal surgery
- The age of the patient for instance young adults and the elderly are more susceptible to PONV
- The gender of the patient females are more susceptible to PONV
- Patients with co-existing conditions such as those who are overweight and/or obese, diabetic, pregnant or suffering from hypothyroidism.
It is evident that some surgeries due to the above factors may trigger the release of 5HT from enterochromaffin-like cells in the visceral mucosa and initiate the emesis reflex and its accompanying feeling of nausea. Some risk factors that can predispose you to getting nausea and vomiting following a surgical procedure:
- Age: Younger patients and the elderly are more at risk of having post-operative nausea and vomiting
- Gender: Women tend to suffer more than men do.
- Nutrition: People who are overweight or obese have a much higher risk of getting nausea and vomiting after a surgery. It is a condition that patients must fast before surgery, as contents in the stomach puts you at a much higher risk of vomiting after a surgery or at least feeling nauseous
- Past history: If you have previously had nausea and vomiting after a surgical procedure and/or you suffer from motion sickness makes you more susceptible to getting nausea and vomiting after an operation
- Cancer therapy: Patients undergoing chemotherapy and radiotherapy are more likely to suffer as well
- Anaesthetic and surgical factors: Sometimes certain types of anaesthetic agents (such as inhaled gases) and medications (such as morphine) can lead to nausea and vomiting. Some surgical factors such as operations around the ear and inner ear, eyes, mouth and some abdominal surgery increase the risk of you getting nausea and vomiting afterwards.
All steps will be taken by the anaesthetists and doctors caring for you to prevent post-operative nausea and vomiting, however, in some instances, it can not be prevented and they will give you medications to ease the discomfort.
The ingested toxin substances such as alcohol can induce life-saving physiological response to these circulating foreign particles. The CTZ is relatively permeable, enabling the circulating substance or mediators to act directly on this centre. Activation of this centre is followed by release of the aforementioned chemical transmitters dopamine and 5HT, which trigger the vomiting centre and cause the release of Ach, thereby leading to induction of nausea and vomiting.
Stimulation of parts of the throat and/or stomach can lead to nerve and chemical transmitter release of information to an area of the spinal cord and brain (known as the nucleus of the solitary tract), which goes on to trigger the vomiting centre and the cascaded of nausea and vomiting through Ach release.
Consequences of vomiting
Severe and prolonged vomiting can cause the following harmful consequences:
- Dehydration, which can be lethal, especially in children
- Protracted vomiting may result in starvation, malnutrition and vitamin deficiency
- Severe post-operative vomiting can increase bleeding, aspiration pneumonia, and induce the re-opening of surgical wounds as a result of involuntary muscle contractions associated with vomiting .
Metabolic alkalosis is a reduction in plasma concentrations of [H + ] cause by a relative deficiency of noncarbonic acids. Under normal circumstances, Hydrochloric acid (HCl) is secreted into the lumen of the stomach during digestion. During this secretion, bicarbonate (HCO3 – ) is added. The HCO3 – is usually neutralised by H + as the gastric secretions are gradually reabsorbed. As a result, there is no net addition of HCO3 – to plasma overall. Vomiting results in a loss of acidic gastric juices from the digestive tract, so that there is an abnormal loss of H + from the body, and hence a loss of reabsorbed H + to neutralise the extra HCO3 – added to the plasma during gastric HCl secretion. This leads to an acid-base disturbance associated with an increase in HCO3 – and a decrease in H + , hence the metabolic alkalosis.
Management and treatment of nausea and vomiting
- Identify the pathway by which each cause triggers the vomiting reflex
- Identify the chemical transmitter involved in the identified pathway
- Choose a drug that is able to act as a preventer of this reflex pathway
- Appropriate drug delivery (e.g. as a tablet, as an injection). The route of administration depends on the state and condition of the patient. Drugs in rectal or parental form are necessary where oral medication is not tolerated or is contraindicated such as after major surgery
- Try to optimise the dose of the medication (usually start with the recommended dose).
If the underlying cause of the nausea and vomiting is unable to be identified, control of the symptoms should be established. It is also important to correct for electrolyte, fluid, and/or nutrient deficiencies.
The members of this class of antiemetics are metoclopramide (Maxolon) and prochlorperazine (Stemitil). Metoclopramide has anti-dopamine action, which stimulates motility of the upper gut without stimulating the gastric, biliary or pancreatic secretions. Its exact mechanism is still unclear, however it is thought that metoclopramide may sensitize the tissues to the action of ACH. On the other hand, prochlorperazine has several activities such as anti-dopamine action, alpha-adrenoreceptor antagonism, weak anticholinergic, antihistamine and serotonin antagonism actions. Thereby its mechanisms of action give prochlorperazine strong antiemetic and antipsychotic properties.
An example of this class of antiemetics is promethazine. Promethazine is a long acting antihistamine with sedative and anticholinergic properties that enhance the antiemetic activity.
5HT3 antagonists are mainly used to prevent or treat nausea and vomiting following cancer chemotherapy, radiotherapy or surgery. The members of this class of antiemetic are palonosetron (Aloxi), granisetron (Kytril), ondansetron, dolasetron and tropisetron. These medicines are potent antiemetic and highly selective antagonists of 5HT3 receptors. Because 5HT3 receptors are located peripherally on vagal nerve terminals and centrally in the CTZ, antagonism of this receptor is an effective method of preventing nausea and vomiting.
An example of this class of antiemetics is hyoscine, which is a belladonna alkaloid. Hyoscine has anti-spasmodic and anti-motility effect on the gut by inhibiting the activity of ACH.
Dietary management of nausea
Nausea with or without vomiting is a common side effect of surgery, chemotherapy, radiation therapy, and biological therapy. Nausea can prevent you from eating enough food and maintaining your nutritional intake and weight.
Dietary strategies to manage nausea include:
- Discuss anti nausea (antiemetic) medications with your doctor
- Avoid eating 1–2 hours before your treatment if this makes nausea worse. Try to ‘catch up’ after treatment
- Avoid foods that:
- are fatty/greasy/fried
- are spicy or hot
- have strong odours.
Article kindly reviewed by:
The DAA WA Oncology Interest Group
Food4Health (Helen Baker Dietitian-APD)
What is Labyrinthitis?
Labyrinthitis is an inflammatory condition affecting the inner part of the ear or the nerves in this region of the ear and is often because of a bacterial or viral infection.
The symptoms of labyrinthitis include fever, pain in the ear, extreme dizziness, odd eye movements that tend to recur, and problems in focusing the eyes. People with labyrinthitis also commonly experience vomiting, nausea, and ringing in the ears. There can be some hearing loss if the cause is an ear infection. The symptoms tend to persist when a person has labyrinthitis, they do not come and go.
Besides noting the symptoms, certain imaging methods can also help with diagnosis particularly if meningitis is suspected. CT scans and MRI scans can sometimes be helpful in diagnosis of labyrinthitis.
Causes and complications:
Labyrinthitis is often a complication of a severe bacterial ear infection such as otis media, and can be due to meningeal infections. Causes can also include an unusual skin growth behind the ear drum and a break in the labyrinthine bone of the ear. A viral infection such as a cold or influenza can also lead someone to develop labyrinthitis. Complications are rare but can include tinnitus, problems with balance, and permanent hearing loss.
Dizziness and nausea can be treated with medications that help with vertigo and are anti -emetic, such as meclizine. Antihistamines and corticosteroids are sometimes given. Antibiotics including those used to treat otis media or meningitis can be used to help treat labyrinthitis. A myringotomy or tympanostomy may also help. The tympanostomy is when a tube is place to act as a shunt to remove fluid buildup, and the tube is placed through the ear drum, the tympanic membrane. A myringotomy is also when an incision is made into the tympanic membrane to drain fluid, but no tube is placed. Where the condition is caused by a virus, antibiotics are not effective.
For reference, male and female betas are representative of what are, in this universe, cis males and females. Therefore, a male beta has a penis, external testicles, and an anus, while a female beta has a clitoris, a vulva and vagina, ovaries, a uterus, and an anus.
The only anatomical difference between male alphas and male betas is that male alphas have at the base of their penis a bulbus glandis, which expands during intercourse, locking the alpha inside of their partner. The bulbus glandis is colloquially referred to as the &ldquoknot&rdquo. Female omegas are anatomically identical to female betas, but are very different hormonally.
Female alphas and male omegas are the most alien to us, as they each have two sets of reproductive organs: both &ldquomale&rdquo and &ldquofemale&rdquo organs are present. Female alphas have an enlarged clitoris that functions as a bulbus glandis (with no further phallic material distal to the knot structure), internal testicles, a vulva, and an anus. Urine is expelled through a urethra separate from the clitoral urethra, which is used solely to conduct semen. In female alphas, the uterus is underdeveloped and the testicles are much larger than the ovaries.
Male omegas do have a penis and testicles, but they are small and often incorrectly referred to as &ldquovestigial&rdquo. Their testicles rarely descend fully, and generally settle just caudal to the inguinal canal. Instead of an anus or vulva, male omegas possess a cloaca, which then subdivides into the vaginal and rectal canals. Both the vaginal canal and the rectal canal have a valve which prevents them from opening at the same time. In male omegas, it is the testicles and &ldquomale&rdquo organs that are underdeveloped, rather than the uterus and ovaries. Both urine and semen are expelled through the urethra in the penis.
(Note: A knot is a swelling at the base of the penis or within the clitoris that locks the penis or clitoris inside of the vagina or cloaca during and after orgasm, to increase chances of conception. Alphas do not always knot, except when with an omega in heat when rut compels them. Knotting sessions can last anywhere from 15 minutes to, in extreme cases, an hour, though they average at 30 minutes.)
Ejaculation, Orgasm, and Autolubrication
Male alphas&rsquo orgasms are almost exclusively ejaculatory, and last from 30-60 seconds. Typical volume of semen ejaculated in a single orgasm is about 25mL. Female alphas&rsquo orgasms are likewise mostly ejaculatory, though slightly less so than those of male alphas. Orgasms last from 30-60 seconds, with ejaculation occurring the entire time. The typical volume of semen ejaculated is about 20mL.
Male betas&rsquo orgasms are generally ejaculatory, and last about 5 seconds. Typical ejaculation volume is 5mL. Female betas&rsquo orgasms generally last around 15 seconds, and are for obvious reasons never produce semen.
Male omegas&rsquo orgasms are ejaculatory about 50% of the time, and generally last about 30 seconds. When ejaculation occurs, semen volume is generally about 0.1mL, though it can be as high as 0.5mL. During estrus, semen production halts entirely and all orgasms are &ldquodry&rdquo. Female omegas&rsquo orgasms last about 30 seconds, and likewise produce no semen.
Although they do possess a vagina, female alphas only self-lubricate when hyperaroused or with extended contact to an omega in heat. Female betas, however, do self-lubricate when aroused, but generally require some artificial lubrication as well for comfortable penetration. Male and female omegas both self-lubricate when aroused and rarely require artificial lubrication.
Manifestation is essentially puberty, during which an individual&rsquos secondary gender begins to affect them biologically and induces the production of hormones and pheromones.
Omegas tend to manifest slightly later than alphas, around 15 or 16. Alphas tend to manifest around 14 or 15. The change is marked by increased pheromone production and sensitivity, and omega manifestation is often heralded by their first heat, though not necessarily. Beta manifestation is often mistaken for no manifestation at all, as it is much more subtle and is often only noticed by the betas themselves, as they become more sensitive to the scents of those around them. Registration of sex is required within a week (or, for omegas, six weeks) of manifestation.
Only male/female sex is identifiable at birth. However, under special circumstances pediatricians can use magnetic resonance imaging to differentiate between males, as male alphas will have a premature knot structure within the normal shape of the penis, and male omegas&rsquo &ldquoanuses&rdquo are actually partial cloacae and are subdivided just past the opening into separate vaginal and rectal tracts. Female alphas can also be differentiated from female betas and omegas, as they have internal testicles which are easily visible on an MRI slightly anterior to and medial of the ovaries. However, female betas and female omegas cannot be reliably differentiated between until puberty, when female betas begin menstruation and female omegas begin their estrous cycle. This procedure is undertaken almost exclusively for health-related concerns, as it is fairly expensive.
Alphas and omegas tend to significantly produce and instinctually react to pheromones. Beta pheromones have been described as comparatively &ldquobland&rdquo, or, alternatively, &ldquosoothing&rdquo. Alphas tend to find omega scents attractive, and vice versa. Alphas will sometimes feel threatened when they scent another alpha during a stressful situation, and react violently. Alphas are also instinctually attracted to the pheromones omegas produce while in estrus, and competition for the privilege to mate can sometimes become violent. Furthermore, if there is extensive contact with an omega in estrus proper, the majority of alphas will go into rut, which increases their mating drive for the duration of contact with the omega and generally several hours after contact ceases. However, rut does not affect alphas as much as estrus does omegas, and rut is never an excuse for forcing oneself on an omega, though it was a legitimate legal defense until 1997. Omegas in estrus proper almost always crave alpha pheromones, but if they feel threatened or stressed they tend to shy away from alphas and seek the company of other omegas, and sometimes betas. There are very few cases of rape perpetrated by an omega in estrus, as they become very weak during estrus proper, but there are a few, mostly upon physically disabled alphas.
Alphas produce large quantities of androstenone, which creates a dominant, intimidating, aggressive aura. Less aggressive alphas, who tend to make better mates, produce more androsterone, which produces a dominant aura without the aggressiveness. When in rut, alpha production of androstenone goes into overdrive.
Betas&rsquo primary pheromone is androstenol, which induces friendly behavior. They tend to produce more alpha-androstenol in the presence of other betas, and beta-androstenol in the presence of alphas and omegas.
Omegas produce mostly estratetraenol and copulins. During heat, their production of both skyrockets and they become extremely attractive to alphas. Even during the glutton stage, their pheromone levels are rising and more alphas will generally take interest in them.
When in non-sexual situations, omega and beta scents tend to be calming, omega scents in an active sense, acting almost as a sedative, and beta scents in a more passive manner. Alphas can, in special circumstances, infuse their scent with command that weakly compels omegas, and, to a lesser extent, betas, to obey them. This is significantly more effective when used upon distressed omegas or omegas in or nearing estrus when applied to other alphas, it generally invokes hostility, sometimes leading to violence.
When a mating bite occurs, the omega&rsquos bonding gland, which is located in the superior trapezius, releases a spike of oxytocin into the omega&rsquos blood, triggering release of vasopressin in the alpha. Omegas will also produce n-undecane in the presence of other alphas when pair-bonded, warning the other alphas off and making them smell &ldquoclaimed&rdquo. Presence of the alpha during the omega&rsquos heat is required to maintain a mating bond if the alpha is absent and the omega suffers an unsuppressed heat, with or without another partner, the pheromonal bond will fade away and the omega will no longer smell claimed. Other alphas will likely make advances.
(Note: Although omega attraction to alpha pheromones and alpha attraction to omega pheromones are very common, it is important to remember that they are not universal and that homosexual and asexual alphas and omegas, as well as betas, do exist.)
Pheromones are produced mainly by scent glands on the wrists, neck, cheeks, and, for omegas, genitals. In claiming a mate, therefore, alphas will generally rub their face and hands on the face and neck of their chosen omega, as an additional warning to other alphas that this omega is claimed. Omegas scent mark their alphas as well, though this tends to be more subtle usually they accomplish this through less specific physical contact, such as hugging or cuddling. However, not all scent marking is necessarily sexual. Families and good friends tend to scent mark each other as well, but as the pheromone production incited by the presence of family and platonic friends is entirely different from that incited by the presence of a potential or claimed mate, the scent transferred differs greatly from that transferred by scent marking from a mate.
Estrus occurs only in omegas, male and female (beta females have a menstrual cycle). It occurs twice a year, generally once in fall and once in spring, though if the omega is under significant mental or physical stress they will often skip one or more heats. There are four stages of estrus: the weight-gaining or &ldquoglutton&rdquo stage, which lasts about one month and during which omegas eat constantly to gain fat for their upcoming trial the &ldquopurging&rdquo stage, which lasts from one to three days and during which the omega&rsquos systems clear and prime themselves for reproduction. At the end of stage two the rectal aspect of the cloaca shrinks and the vaginal aspect opens wider, and estrus proper, or &ldquoheat&rdquo begins, which can last anywhere from eight to fourteen days, and during which the omega is essentially delirious in their instinctual desire to be bred (pain receptors also shut down during this phase). It is common for omegas to display lordosis behavior during estrus proper, especially if they are in the presence of a previously accepted mate. The fourth stage can go two ways. Either the egg is fertilized and the omega&rsquos body proceeds into pregnancy, or the egg is left unfertilized and the endometrium is reabsorbed into the body.
Omegas going through estrus have three main options: go through heat with another person (usually an alpha), obtain and administer heat suppressants, or go through heat alone.
- Pros of partnered heat: biological imperatives fulfilled, no suppressant side-effects
- Cons of partnered heat: potential STDs and unwanted pregnancies
- Pros of suppressants: heat much more mild (has been described as a &ldquolow-level buzz&rdquo), no time needed off work/school, no potential for STDs or unwanted pregnancy
- Cons of suppressants: potential side effects (headache, nausea), does not burn off all weight gained during glutton period (can lead to obesity or heart problems), heat tends to last slightly longer, cost
- Pros of heat alone: no potential for STDs or unwanted pregnancy, no drug side effects
- Cons of heat alone: medical professional or family member must care for omega through heat, heat tends to be more extreme than on suppressants or with an alpha, omegas can injure themselves or become severely dehydrated during heat
Suppressants and Birth Control
Altrenogest, C21H26O2, a progestogen, has both suppressant and contraceptive properties. It can be taken orally in its microionized form, or it can be taken as a shot. Possible side effects: weight gain, depression, hair loss, headache, nausea, sore breasts.
The only birth control without suppressant effects is a penetrating-partner injection of immunoglobulin A or G (IgA or IgG).
Female betas ovulate and menstruate once a month. Some female alphas do the same, but they must be exceedingly healthy and unstressed to do so, and they therefore tend to do so only in full adulthood. Omegas, male and female, have an estrous cycle instead of a menstrual one.
Omegas, beta females, and occasionally alpha females can become pregnant. Pregnancy generally lasts close to 40 weeks. In beta pairs, 3.32% of births produce twins, and 0.137% produce triplets or other multiples. In alpha-omega pairs, however, multiple births are significantly more common. 19.3% of alpha-omega births produce twins (32.4% of children are twins), and 1.25% produce triplets or higher-order multiples.
When pregnant, omegas self-isolate and become very hostile toward everyone but close family and their mate. If approached by a stranger, they will sometimes attack, and if they are in the presence of their mate they will generally cling to and hide behind them, snarling at the potential threat. Alphas also become very protective of pregnant omegas whom they know, especially their mates, and also become hostile toward strangers and anyone who approaches too quickly or comes too close. This is a leading cause of violence among alphas and omegas, as mated pairs will generally attack together, though the omega usually lets the alpha do the majority of the fighting. This is a residual instinct from when alphas who desired an omega who was already mated would sometimes wait for the omega to give birth and then kill the baby, claiming the omega for their own. The most violent of alphas would then proceed to eat the child. This is now extremely rare and highly illegal, but the protective instinct is preserved. Because of this, omegas with children whose alpha has died almost never re-mate until the child is an adult, if at all, despite the fact that the undeniable evidence of their fertility makes them highly desirable. They will, however, sometimes form romantic or sexual unions with betas or other omegas, although these unions are not legally recognized.
Alpha females have narrower hips than beta females and omegas (omega females tend to have very wide hips), so they are more likely to require a Caesarian section than beta and omega females are. In fact, more than 50% of alpha female births are by C-section. However, alpha female hips are wider than alpha and beta male hips, so they can reasonably give vaginal/cloacal birth. Omega male hips tend to be slightly narrower than beta females&rsquo, but during pregnancy the pelvic opening widens as the ligaments of the sacroiliac joint loosen significantly, much more than for beta or omega females. Male omegas keep the wider hips after their first pregnancy.
Breasts, Lactation, and Nursing
Male omegas do lactate, but only during and shortly after pregnancy. Their breasts do not remain enlarged as females&rsquo do, and are generally small even when lactation occurs. Beta and omega females lactate as well, and retain the fatty tissue in their breasts. Alpha females never lactate their breasts are composed entirely of fatty tissue, containing no actual milk-producing glandular tissue, and are generally small, comparable to the size of omega males&rsquo breasts during late pregnancy most female alphas and pregnant male omegas have AA or A-cup breasts. Omega females have larger breasts, tending toward C to DD-cups. Beta females are average at B or C-cups.
'Disgusted' rats teaching scientists about nausea, work may lead to new cancer treatments
IMAGE: This is an image of a rat displaying the disgust reaction called "gaping. " This reaction is helping researchers understand brain mechanisms that produce nausea in humans. view more
Credit: University of Guelph
Nausea is a common and distressing side effect of many drugs and treatments. Unlike vomiting, nausea is not well understood, but new research by University of Guelph scientists may soon change that.
Guelph PhD student Katharine Tuerke, neuroscience researcher Cheryl Limebeer and Prof. Linda Parker in the Department of Psychology believe they've found the mechanism in the brain that is responsible for the sensation of nausea - with the help of some "disgusted" rats.
Their study was published this week in Journal of Neuroscience.
"Although everyone has experienced nausea at some point, its neurobiology is poorly understood due to a lack of animal models," said Parker, who holds the Canada Research Chair in Behavioural Neuroscience.
"We know about vomiting. The vomiting reflex is very well characterized, but the experience of nausea is something that little is known about. How is it generated? Where is it generated?"
Although rats can't vomit, they do display a disgust reaction called gaping when re-exposed to a taste that made them feel nauseous in the past. Therefore, these gaping reactions in rats provide a model to understand brain mechanisms that produce nausea in humans.
Using this gaping model, the Guelph researchers, along with University of Toronto professor Paul Fletcher, discovered that serotonin release in the visceral insular cortex may be responsible for the sensation of nausea.
The insular cortex is a site of taste and illness input in the brain. Based on its cell structure and inputs, the insular cortex can be divided into two regions: the gustatory insular cortex and the visceral insular cortex. The gustatory insular cortex receives taste input and the visceral insular cortex receives input from regions of the gut that may produce the sensation of nausea.
Previous research has shown that the neurotransmitter serotonin is critical for the production of nausea. Indeed, classic anti-emetic drugs such as ondansetron that are used in chemotherapy treatment are drugs that block the action of a type of serotonin receptor, serotonin-3 receptors.
The researchers first demonstrated that depletion of serotonin in the entire insular cortex prevented the nausea-induced gaping reactions in rats, suggesting that serotonin activation in this region is necessary for the production of nausea.
Next they examined the effects of delivering drugs that either activate serotonin-3 receptors or block serotonin-3 receptors to specific regions of the insular cortex. In the visceral insular cortex, but not the gustatory insular cortex, activating serotonin caused nausea (produced gaping reactions) and blocking serotonin reduced nausea (eliminated gaping reactions).
These data suggest that the activation of the visceral insular cortex by serotonin may be responsible for the production of the elusive sensation of nausea, which is so difficult to treat.
Tuerke and Parker hope their work will lead to a better understanding of basic neural processes affected by prescribed drugs, with specific applications to controlling nausea and vomiting caused by cancer chemotherapy.
The research was supported by the Natural Sciences and Engineering Research Council of Canada.
Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
Risk Factors for Noninfectious Diseases
Many of the same risk factors increase a person&rsquos chances of developing a diversity of noninfectious diseases. These common risk factors include age, gender, genes, and exposure to environmental dangers such as radon. Behaviors such as smoking, unhealthy diet, and physical inactivity are also common environmental risk factors for many noninfectious diseases. These behaviors all contribute to obesity, high blood pressure, unbalanced blood lipid levels, and high blood glucose levels &mdash in other words, to metabolic syndrome. This syndrome, in turn, is a major risk factor for cardiovascular diseases and type 2 diabetes. One of the single most important behavioral factors contributing to metabolic syndrome is the consumption of large amounts of sweetened beverages such as soft drinks (Figure (PageIndex<2>)).
Figure (PageIndex<2>): Avoiding over-sized servings of sugary drinks is an important way to help prevent metabolic syndrome.
Most behavioral risk factors for noninfectious diseases can be avoided. That&rsquos why many noninfectious diseases are considered preventable. Their risk can be reduced by modifying behaviors and making healthier lifestyle choices. In fact, an estimated 80 percent of cases of cardiovascular diseases and type 2 diabetes and 40 percent of cancer cases could be avoided through lifestyle changes. Interventions that target common behavioral risk factors can make a big impact on a nation&rsquos noninfectious disease burden. For example, laws taxing tobacco products and curbing smoking in public places have been shown to reduce rates of smoking, which is the main risk factor for lung cancer.
Other risk factors for noninfectious diseases &mdash including age, gender, and genes &mdash cannot be avoided or modified. In terms of age, most noninfectious diseases become more common as people get older. Some noninfectious diseases, such as certain types of cancer, are more common, or occur only, in one sex or the other. Genes are wholly responsible for some inherited noninfectious diseases, such as cystic fibrosis. Genes may also affect individual susceptibility to many other noninfectious diseases that are caused mainly by environmental factors. For example, genes may influence how likely a person is to develop metabolic syndrome for a given lifestyle, and ultimately how likely the person is to develop cardiovascular disease and type 2 diabetes. It is important to take these unavoidable risk factors into account in diagnosing and screening for noninfectious diseases and establishing individual treatment and prevention guidelines.
Signs and symptoms of heavy metal toxicity
Signs and symptoms of toxicity depend on the heavy metal involved and whether an exposure causes acute toxicity or chronic and subtle effects.
Signs and symptoms of acute toxicity
- Severe, rapid in onset
- Cramping, nausea, vomiting, pain
- Breathing difficulties
- Skin rash
Signs and symptoms of chronic exposure
- Develop slowly over months or years
- Skin changes
- Impaired cognitive, motor and language skills
- Nausea, lethargy, malaise
- Emotional instability
The heavy metals that cause the most significant skin changes and are discussed in more detail include arsenic, silver, gold and mercury.
Watch the video: Approach to Nausea and Vomiting Video (August 2022).