CHICAGO: Nerves that sense the icy slap of an arctic wind or just a cool breeze take their orders from a single protein, US researchers said, shedding new light on how we experience cold.
Prior studies have suggested cold-sensing neurons are specialized, with some detecting painful cold sensations and others detecting more pleasant ones. But researchers at the University of Southern California have found that even though most cold-sensing neurons make use of a single protein known as TRPM8, they can detect a range of sensations.
“We all know when we stimulate our teeth with cold we get this distinct cold sensation,” said David McKemy, whose study appears in the Journal of Neuroscience. “You get this sharp transient shooting pain and this dulled, aching sensation,” McKemy said.
Other groups have attributed that to two different cold sensory neurons. “There was a notion that there were neurons called cool fibers and there were others involved in detecting cold pain,” he said. He said he had expected neurons that express, or produce, TRPM8 to be of the pleasant cool variety.
To study the neurons, McKemy genetically engineered mice so that neuron fibers that expressed this protein would be fluorescent green. He then traced these cold-sensing fibers from sensory neurons near the spinal cord to nerve endings in the skin. “What our study suggests is that even though these neurons express this single protein, it looks like they have diverse functions,” he said.
Humans appear to share the same mechanism, he said. McKemy said nerves that produce TRPM8 account for about 75% of all cold-sensing neurons. He believes there are others that are specific to pain, such as when the skin is burned in frostbite. Researchers study cold-sensing neurons to grasp the molecular mechanisms of sensation, an understanding that may lead to better drugs for pain relief.
Next time you’re in a meeting, try this little experiment: Take a big yawn, cover your mouth out of courtesy, and watch and see how many people yawn. There’s a good chance that you’ll set off a chain reaction of yawns. Before you finish reading this question of the day, it’s likely that you will yawn at least once. Don’t misunderstand, we aren’t intending to bore you, but just reading about yawning will make you yawn, just as seeing or hearing someone else yawn makes us yawn.
What’s behind this mysterious epidemic of yawning? First, let’s look at what a yawn is. Yawning is an involuntary action that causes us to open our mouths wide and breathe in deeply. We know it’s involuntary because we do it even before we are born. Research shows that 11-week-old fetuses yawn.
There are many parts of the body that are in action when you yawn. First, your mouth opens and jaw drops, allowing as much air to be taken in as possible. When you inhale, the air taken in is filling your lungs. Your abdominal muscles flex and your diaphragm is pushed down. The air you breath in expands the lungs to capacity and then some of the air is blown back out.
While the dictionary tells us that yawning is caused by being fatigued, drowsy or bored, scientists are discovering that there is more to yawning than what most people think. Not much is known about why we yawn or if it serves any useful function, and very little research has been done on the subject. However, there are several theories about why we yawn.
Yawning is a powerful non-verbal message with several possible meanings, depending on the circumstances. The claim that yawning is caused by lack of oxygen has not been substantiated scientifically. However, the exact causes of yawning are still undetermined.
Here are the three most common theories:
1.The Physiological Theory — Our bodies induce yawning to drawn in more oxygen or remove a build-up of carbon dioxide. This theory helps explain why we yawn in groups. Larger groups produce more carbon dioxide, which means our bodies would act to draw in more oxygen and get rid of the excess carbon dioxide. However, if our bodies make us yawn to drawn in needed oxygen, wouldn’t we yawn during exercise? Robert Provine, a psychologist at the University of Maryland, Baltimore County, and a leading expert on yawning, has tested this theory. Giving people additional oxygen didn’t decrease yawning and decreasing the amount of carbon dioxide in a subject’s environment also didn’t prevent yawning.
2. The Evolution Theory — Some think that yawning is something that began with our ancestors, who used yawning to show their teeth and intimidate others. An offshoot of this theory is the idea that yawning developed from early man as a signal for us to change activities.
3. The Boredom Theory — In the dictionary, yawning is said to be caused by boredom, fatigue or drowsiness. Although we do tend to yawn when bored or tired, this theory doesn’t explain why Olympic athletes yawn right before they compete in their event. It’s doubtful that they are bored with the world watching them.
A recent hypothesis raised in 2007 by Andrew C. Gallup and Gordon Gallup of the University of Albany states that yawning may be a means to keep the brain cool. Mammalian brains operate best when they are cool. In an experiment, he showed several groups of people videos of other people yawning. When the subjects held heat packs up to their foreheads while viewing the videos, they yawned often. But when they held cold packs up to their foreheads or breathed through their noses (another means of brain cooling), they did not yawn at all. A similar recent hypothesis is that yawning is used for regulation of body temperature.
Another hypothesis is that yawns are caused by the same chemicals (neurotransmitters) in the brain that affect emotions, mood, appetite and other phenomena. These chemicals include serotonin, dopamine, glutamic acid and nitric oxide. As more (or less) of these compounds are activated in the brain, the frequency of yawning increases. Conversely, a greater presence in the brain of opiate neurotransmitters such as endorphins reduces the frequency of yawning. Patients taking the selective serotonin reuptake inhibitors Paxil (paroxetine HCl) or Celexa (citalopram) have been observed yawning abnormally often. Anecdotal reports by users of psilocybin mushrooms often describe a marked stimulation of yawning while intoxicated, often associated with excess lacrimation and nasal mucosal stimulation, especially while “peaking” (i.e. undergoing the most intense portion of the psilocybin experience). While opioids have been demonstrated to reduce this yawning and lacrimation provoked by psilocybin, it is not clear that the same pathways that induce yawning as a symptom of opioid abstinence in habituated users are the mode of action in psilocybin-induced yawning. While even opioid-dependent users of psilocybin on stable opioid therapy often report yawning and excess lacrimation while undergoing this entheogenic mushroom experience, there are no known reports in the literature that suggest psilocybin acts as any sort of general opioid antagonist. Psilocybin-induced yawning in opioid-habituated users does not appear to produce other typical opioid withdrawal symptoms such as cramping, physical pain, anxiety, gooseflesh etc.
Recent research carried out by Catriona Morrison, a lecturer in psychology at the University of Leeds, involving monitoring the yawning behaviour of students kept waiting in a reception area, indicates a connection (supported by neuro-imaging research) between empathic ability and yawning. “We believe that contagious yawning indicates empathy. It indicates an appreciation of other people’s behavioural and physiological state,” said Morrison.
Another theory is that yawning is similar to stretching. Stretching, like yawning, increases blood pressure and heart rate while also flexing many muscles and joints. It is also theorized that yawning helps redistribute surfactant, an oil-like substance which coats the lungs and aids breathing. Some have observed that if one tries to stifle or prevent a yawn by clenching one’s jaws shut, the yawn is unsatisfying. As such, the stretching of jaw and face muscles seems to be necessary for a satisfactory yawn.
Yet another theory is that yawning occurs to stabilize pressure on either side of the ear drums. The deep intake of air can sometimes cause a popping sound that only the yawner can hear; this is the pressure on the inner ear stabilizing. This commonly occurs in environments where pressure is changing relatively rapidly, such as inside an airplane and when travelling up and down hills, which cause the eardrums to be bent instead of flat. Some people yawn when storms approach, which is a sure sign that changes in pressure affect them.
Some movements in psychotherapy, such as Re-evaluation Counseling or co-counselling treatments, believe that yawning, along with laughter and crying, are means of “discharging” painful emotion, and therefore can be encouraged in order to promote physical and emotional healing.
The simple truth is that even though humans have been yawning for possibly as long as they have existed, we have no clue as to why we do it. Maybe it serves some healthful purpose. It does cause us to draw in more air and our hearts to race faster than normal, but so does exercise. There’s still much we don’t understand about our own brains, so maybe yawning is triggered by some area of the brain we have yet to discover. We do know that yawning is not limited to man. Cats, dogs, even fish yawn, which leads us back to the idea that yawning is some form of communication.
2.An action used as an unconscious communication of psychological decompression after a state of high alert.
3.A means of expressing powerful emotions like anger, apathy, apprehension, remorse or boredom.
4.An excess of carbon dioxide and lack of oxygen in the blood.
5.A way of displaying (or indicative of) apathy.
6.Tiredness
Some Interesting Yawning Facts:-
* The average yawn lasts about six seconds.
* Your heart rate can rise as much as 30 percent during a yawn.
* 55 percent of people will yawn within five minutes of seeing someone else yawn.
* Blind people yawn more after hearing an audio tape of people yawning.
* Reading about yawning will make you yawn.
* Olympic athletes often yawn before competition
Bats are the only mammals that can fly. Their feet are not strong enough to support standing or walking for a long time. They have a wingspan ranging from six feet to six inches.
But the wings don’t produce enough lift to help them take off from a dead stop and the hind legs, too, are so small that they can’t run to build up the necessary take-off speed. Hence, unlike birds, bats can’t launch themselves into the air from the ground. But the animals have a unique physiological adaptation that lets them hang upside down without exerting any energy. For this, they fly into position, pull their claws open and find a surface to grip. This way, they can take the weight off their tired limbs. Their breast-feeding babies, too, have no choice but to hang in limbo with their moms. And together they reap the benefits of downward gravitational pull. Moreover, hanging upside down is a great way to hide from danger.
Bats invert our common beliefs regarding their eyesight. A nocturnal creature, the bat hunts its prey at night and rests for the evening’s events by day. Also, their food resources are limited. So from whatever little food they get, they must efficiently use their total energy for maintaining their basal metabolism, flying, reproduction, etc. Birds, being powerful fliers, have well-developed chest and wing muscles and spend more energy to take off from the ground, against the gravitational pull. Bats avoid spending precious energy for this process by hanging upside down in high raised ceilings. As they drop down from the ceiling they start flying. An intelligent energy conservation strategy indeed!
Headaches — barring migraine headaches, which are of a different type — are a painful symptom of an underlying systemic problem or cause.
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There may be various reasons why one may develop a headache, each of which has a different trigger mechanism. But the resulting headache in all cases is a red flag signaling a disorder somewhere in the body or in the nervous system.
Generally, the cause of a headache can be dissected and understood once it is traced back to its physical or neurological origin. The actual pain we experience does not stem from the brain matter contained in the skull, but from the pain felt by the sensitive coverings of the brain, and of the large veins and arteries which drain fluid from that organ. Sinus, tooth, ear and muscle pain produce headaches by radiating the pain to these sensitive coverings when they tense, and when the muscles spanning the neck and the base of the skull contract.
Complaints of headaches commonly fall under the heading of vascular headaches, and result when the arteries in the skull dilate, often because of triggers that include hunger, caffeine deprivation or hangovers. Severe emotional trauma causes muscles over the back and at the lower part of the head and the neck to contract, resulting in an instantaneous headache.
The important thing to remember when one experiences a headache is that it is a symptom of underlying disorders with multiple causes that merit diagnosis.
Sunlight is crucial to our health and when we don’t get enough of it, both our mood and our health suffer. This is especially true in regions where temperatures dip to sub-zero levels and sunlight is scarce.
But why does this happen? When you’re out in the sun, your serotonin levels go up. Serotonin is the hormone that elevates our mood. In the winter, we don’t get much sunlight, so we don’t produce as much serotonin. Hence, we feel blue!
There’s another hormone that’s affected in this season. The sleep hormone, melatonin — which is produced by the pineal gland in our brain, is also affected by light and dark. Melatonin is the hormone that lets our body know i it s time to sleep. When it’s dark, your melatonin levels increase. So, if you find yourself feeling sleepy these days — when the sun sets earlier than in the summer days — it’s due to the increase in melatonin.
In winter, we not only have low levels of serotonin (the feel-good hormone) but our melatonin (the sleep hormone) kicks into gear earlier in the day, making us want to retire sooner. No wonder we feel a little out of sorts during winter!
