We blink our eyes to lubricate and filter them. Blinking our eyes, to keep them from drying up, and to prevent foreign matter from entering and irritating our eyes. Blinking also coats the eyelid and eye lashes with the lubricant it secretes, to prevent them from drying up. Yet another benefit of blinking is to shield the eye from foreign bodies. Our eyelashes- short, curved, hairs- attached to the eyelids serve as dust catchers.
Most of us have gone through the phenomenon of legs turning numb as a consequence of sitting in a particular posture for a long time. The sciatic nerve controls and provides sensation to the muscles of our buttocks, thighs, feet and legs. This nerve runs down from the hips to the legs. Anything that puts pressure on this nerve as with prolonged sitting can hinder the nerve function or sensation of the lower legs. This hindering of the nerve function due to compression leads to the numbness of the feet. When we sit for a prolonged period in a particular posture, it leads to the accumulation of blood in the legs and the ankle region restricting the draining away of the deoxygenated blood by the veins. The result is the gradual depletion of oxygen in the legs, which causes a dull aching pain or heavy feeling. Diseases like diabetes, lumbar sodalities and acute weakness due to malnutrition may also cause such a problem.
Though it lives in the sea, whales are warm-blooded mammals. While surfacing, they take in oxygen through the blowhole on top of its head. Then, filling its large elastic lungs connected to the blowhole, the whales dive to feed. While they are underwater, the whales' bodies heat up the air. When they resurface, the air in their lungs are forced out of the blowhole. This action is called spouting, or blowing. When the warm air comes in contact with the cool outside air, it condenses and turns into a steamy spray. The whales' spout can shoot up to 20 feet high in the air.
Moles, which appear on different parts of our body, are usually brown in color (due to the high presence of melanin pigment which gives the skin its color) and vary in sizes as well as shapes. They can be flat or slightly raised above the skin, and may even contain body hairs. They originate from pigmented cells in the skin called melanocytes. Almost everyone has moles, which are usually present either since birth or develop during their early years. Some also get moles later on. Miles, which may darken when exposed to sunlight, do not itch or hurt and are also considered by many people as beauty marks.
Rust is iron oxide. It is created when iron gets burnt by uniting with oxygen dissolved in water. When a drop of rain falls on a bright iron surface, the drop will remain clear for a short time. But the iron and oxygen in the water soon begin to unite and form iron oxide. the drop turns reddish and rust is suspended in the water. When the water evaporates the rust forms a reddish coat on the iron itself. Also, it spreads even in dry air as the rough spot of rust retains moisture again. So iron has to be covered either by plaster or paint.
Stars twinkle when we observe them through different layers of swirling air in the Earth's atmosphere. These layers have different temperatures and density. When light from a star, travelling millions of miles, passes through these layers, it constantly gets refracted by each layer of temperature and moving air several times in random directions. This refraction distorts the image of the star slightly in brightness and position, making it look as if it is moving and winking. this distorted image of the star appears to our eyes as a twinkling one. Thus, stars themselves do not twinkle, but appear to do so.
If the Cup of hot tea is made with boiling water, it will, in theory, freeze faster than the cup of water, because heating drives out the air bubbles that can slow down the freezing process. Ice formed at high pressure has a different crystal structure and density from ordinary ice. Rime is one such ice which is formed on cold objects when drops of water crystallize on them and can be observed when the temperature drops during the night. This is why cold water will take a longer time to freeze.
No two clouds are exactly alike and they always change their shape. The reason behind having different types of clouds is that cloud formation takes place at different heights and at different temperature.
Laughter is the biological reaction of human beings to moments of humor. Depending upon the extent and pitch, laughter can be subcategorized as giggles, chuckles,
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