There are a few questions that i have wondered all of my life.. I hadnt made any research about them until now.. I am sure all of you have asked the same questions to yourself at least one time in your life.I hope they will reduce your question marks to some extent..
Here we go..
1-Why do we itch ? What happens under our skin when we itch ?
Itching, also known as pruritus, starts with some kind of external stimuli, including bugs, dust, clothing fibers and hair. Like tickling, itching is a built-in defense mechanism that alerts your body to the potential of being harmed. In this case, it might be the potential of being bit by a bug.
When the stimuli lands on your skin, it may not bother you at first, but soon it will begin to rub back and forth across your skin. Once the hair or dust scratches your skin's surface layer, receptors in the dermis of the skin will become irritated. In a split second, these receptors send a signal through fibers in the skin to your spinal cord and then up to the cerebral cortex in your brain.
The same fibers that send itching signals are also used to send pain signals to the brain, which once led some scientists to believe that itching was a form of light pain. That notion has since been dispelled by research, which showed that pain and itching elicit opposite responses. Pain causes us to withdraw and itching causes us to scratch.
As soon as we feel an itch, our first natural response is to scratch the spot of the itch with our fingernails. The reason for this response is simple -- we want to remove the irritant as soon as possible. Once you've scratched the area of irritation, you are likely to feel some relief. When your brain realizes that you've scratched away the irritant, the signal being sent to your brain that you have an itch is interrupted and therefore no longer recognized by the brain.
Even if you don't remove the irritant, scratching will at least cause pain and divert your attention away from the itching. The irritant that caused the itching is very small, maybe only a few microns in length, so it disturbs only a few nerve endings. When you use your fingernail to scratch the spot where the irritant is, you not only remove the irritant but you irritate a lot more nerve endings than the irritant.
2-Why can't we tickle ourselves ?
So, if someone else's touch can tickle us, why can't we tickle ourselves? Much of the explanation for this question is still unknown, but research has shown that the brain is trained to know what to feel when a person moves or performs any function. We aren't aware of a lot of the sensations generated by our movements. For example, you probably don't pay much attention to your vocal cords when you speak. For the same reason, we can't tickle ourselves. If we grab our sides in an attempt to tickle ourselves, our brain anticipates this contact from the hands and prepares itself for it. By taking away the feeling of unease and panic, the body no longer responds the same as it would if someone else were to tickle us.3-Why do we get hiccups?
Most of us have experienced hiccups, an uncomfortable, sometimes embarrassing, but usually short-lived experience. But sometimes hiccups persist for a long period of time and can be a sign of serious underlying disease.
What are hiccups?
Hiccups are bursts of inspiratory (breathing in) activity. The muscles we use when we take in a breath are the intercostal muscles situated between the ribs, and the diaphragm — a sheet of muscle below the lungs.
Most simple cases of hiccups come after eating or drinking too much or too quickly. The stomach, which is situated right below the diaphragm, becomes distended and irritates it. This will cause the diaphragm to contract, as it does when we breathe in.
Sometimes hiccups will occur because of a disturbance to the nerve pathways from the brain to the muscles involved. This explains why hiccups may occur with temperature changes or emotional situations. It is also the reason that a sudden shock can sometimes abolish an attack.
Persistent hiccups may signify problems in the brain, spinal cord or any of the structures around the diaphragm or chest wall.
Everyone has their own pet remedy for curing hiccups. Simply holding your breath or dropping 1-2 drops of lemon is often effective.
4-Why do we sneeze?
Once that tingling and twitching starts in your nose, there's no stopping it. A whole-hearted sneeze makes us feel so much better and there's a reason behind it. Sneezing is one of the body's ways of expelling harmful substances that enter our body. The nose works as an air purifier, cleansing the air that enters of bacteria and other particles. So when viruses and bacteria multiply in our nose during a cold, or a cloud of dust blows in our face, or even when we have an allergic reaction, the nerve endings in our nose get irritated and with a blast of air, the nose sweeps its passageways clean.
A sneeze is formed by the spasm of the chest and of the pharynx that connects the esophagus and the nasal cavity. When the nerve endings in the lining of the nose detect the irritating substances, they send impulses to the part of the brain that controls involuntary actions. The brain then sends signals to the chest muscles to squeeze the lungs. The pharynx also shuts to prevent the air being squeezed out of the lungs into the mouth. And so, with a loud blast, the air is expelled through the nose in the form of a sneeze.
Interestingly, some people sneeze when they walk into bright sunlight. It is said that this is a reaction to the ultraviolet rays of the sunlight irritating the nose lining.5-Why do we yawn ?
THE TRUTH IS that we don’t completely understand why people, or animals for that matter, yawn.
It’s widely assumed that yawning occurs because we are tired or bored or because we see someone else doing it, but there isn’t any hard evidence to support these beliefs.
Scientists do not purport to know all of the biological mechanisms of the yawn, but tend to agree that a yawn is an involuntary respiratory reflex, which regulates the carbon dioxide and oxygen levels in the blood.
Technically, a yawn is the reflex opening of the mouth followed by the deep inhalation and slow exhalation of oxygen.
The very act of yawning is but one of a number of involuntary reflexes controlled by the spinal and nerve centers.
Scientists speculate that the onset of a yawn is triggered either by fatigue, or by sheer boredom as, at those times, breathing is shallow, and little oxygen is carried to the lungs by the oxygen-toting cardiovascular system.
When one yawns, his or her alertness is heightened, as the sudden intake of oxygen increases the heart rate, rids the lungs and the bloodstream of the carbon dioxide buildup, and forces oxygen through blood vessels in the brain, while restoring normal breathing and ventilating the lungs.
This quite plausible theory of yawning falls short of explaining many aspects of yawning. Scientists explain away the "contagious" nature of yawning, that is when one person's yawn triggers another nearby to yawn, as due to the power of suggestion, but are at a loss when attempting to explain why yawning occurs excessively in patients with lower brainstem damage or with multiple sclerosis.
Other unlocked mysteries include why fetuses in the womb yawn, when it is a well-known fact that they do not intake oxygen into their lungs until after live birth, or why individuals with high concentrations of oxygen in their blood streams yawn.
Until these questions are answered, do not assume that a person who yawns in your presence is bored with what you are saying, or suffers from exhaustion. Simply be pleased that he or she is not bored to death.
