IF ONE HAS A DRINK SOON AFTER EATING MINTS THE INSIDE OF THE MOUTH FEELS MUCH COLDER THAN NORMAL, WHAT CAUSES THIS ??

     Mint tastes ‘cool’ because of its anaesthetic properties. Menthol, the essential oil in the mint, deadens the hot receptors in the mouth over the cold receptors.

     Nerve endings constantly generate a low background signal that the brain generally ignores. When the noise from the hot receptors is reduced by exposure to mint oils, the noise from the cold receptors stands out in comparison. The brain then interprets these signals as a cold sensation.

     Other essential oils have similar anaesthetic or analgesic properties. Oil of clover is effective in reducing low-level, topical pains and was commonly prescribed by dentists for relieving both toothache and sore gums.

     Oil of wintergreen has a wonderful ‘icy-hot’ feel that can soothe aching muscles. The cool sensation comes from the differential anaesthetic action on the hot receptors in the skin. When this wears off, the rebound of activity from the awakening receptors feels ‘hot’. These two essential oils are still an ingredient in some over-the-counter ointments.Courtesy : The Hindu.

WHY DO INFANTS CRY SOON AFTER BIRTH ??

        Inside the womb the child  is in a warm protected environment. When it is brought out it experiences a total change in the environment. The outside temperature and air stimulates the skin (proprioceptive impulse). This stimulation makes the child take a deep breath (a good gasp). When the air gets into the lungs in the first gasp it results in a cry. It repeatedly takes up this deep breathing and establishes the regular respiratory cycle.

       This cry is one of the five parameters (Apgar count) to assess the child’s condition soon after birth. This is done at one minute and five minute after birth. In a normal child the first cry is expected to be a vigorous or lustrous one. A varied cry is also a way of interpreting the condition of the child (normal or otherwise), according to Dr. Ananthakrishna, an eminent paediatrician.

       If the cry is irritable in nature it may be a child with brain injury. If it is feeble cry it could be due to a respiratory problem or a brain problem such as intracranial bleeding or asphyxia. The feeble cry may also indicate a problem in the lung such as immaturity of the lungs in a low birth weight baby (pre-maturity). It could also be due to aspiration of fluid from the bag of membranes (bag in which the child floats in the intrauterine period) which encircles the child.

       The aspiration contents could also be the meconium (first dark motion passed by the child). The cry thus becomes a very valuable index for assessment as a routine in the newborn nurseries.Courtesy : The Hindu.

WHAT MAKES THE EARTH ROTATE ??

          The earth rotates simply because it has not yet stopped moving. The Solar system, and indeed the Galaxy, were formed by the condensation of a rotating mass of gas. 

   

          Conservation of angular momentum meant that any bodies formed from the gas would themselves be rotating. As frictional and other forces in space are very small, rotating bodies, including the Earth, slow only very gradually.Courtesy : The Hindu.

WHY DOES OUR HAIR CHANGE ITS COLOUR AS WE AGE ??

          Hairs are the appendages of the skin generated from the epidermal layer. Hair is a made up of keratin a highly insoluble and mechanically stable fibrous protein. This keratin is not only found in hairs but also in the skin. Actually keratin is produced from the keratinization zone of the epidermis, which is the outer most layer of the skin. In the skin it provides water proofing quality.

          
              The keratin is generally pigmented. It is intensively pigmented in the hair. The dark colour of the hair is due to the presence of high concentration of melanin pigments in it. The skin colour is also due to the presence of this pigment in the keratinocytes. The keratin gets its melanin pigments from melanocytes, which found in the inner layer of the epidermis, which is found just beneath the keratinizing layer. The melanocytes gave long processes which extent between and under the cells of the epidermis. The melanin granules formed in the melanocytes pass along their branches and are secreted at their tips. The granules are subsequently engulfed by the keratinocytes, which make up 90 per cent of the epidermal cells.

         

Melanin is a protein like polymer of the amino acid tyrocin. In its biosynthesis tyrocin is converted into dihydroxy phenyl alanine (DHPA) by oxidative enzymes amongst which tyrocin is particularly important. Then a series of reactions take place during which polymerization occurs to form the final melanoprotein.

The hair grows only from the keratinocytes of the germinal matrix of the hair follicle. This germinal matrix lies in the proximal enlargement of the root hair, called the hair bulb. The hair shaft, which projects from the surface, consists of an inner medulla, an intermediate cortex and an outer cuticle. All these parts are made up of cornified cells.

           The medulla is composed of polyhedral cells; the cortex consists of elongated cells with inner lumen. These cells are united to form flattened fusiform fibres. The lumens of these cells contain pigmented granules in dark hair and air space in white hair.

          The development of white hairs because of the absence of melanin pigments, may be due to the absence of one or more enzymes, necessary for the DHPA path way. It will lead to the failure of melanin accumulation in the keratinocytes, found in the hair bulb, from which hair is growing. Usually such physiological disorder occurs in the old age, which results in the growing of gray and white hairs in the body.Courtesy : The Hindu.

WHY DO BIRDS FLY IN FORMATION SHAPED LIKE THE ALPHABET “V” ? WHICH BIRD WORKS THE HARDEST IN SUCH A FORMATION AND WHY ??

          The bird in the lead (at the forward point of the “V”  formation) works the hardest by being the first to ‘break through’ the air ,which offers resistance to its flight. Just as a boat leaves a V-shaped wake of smoother water behind it, the lead bird leaves a V-shaped wake of slightly ‘smoother’ air behind it (actually the lead bird creates a trial of air turbulence that helps lift along the V-shaped direction),and it is a bit easier for the other birds to fly in the wake of the lead bird. 

          If you watch a V-formation carefully, you’ll notice that the lead bird does not stay in that position for very long and will drop back into the formation , while another, not-as-tired bird takes the lead, breaking through the air first. Courtesy : The Hindu.

why does snow melt faster around a tree trunks?

  Most of the tree trunks are dark in colour and absorb heat energy from the sun, so that the heat travel at the base of a tree is higher than it is just outside the ring that appears in the snow. Tree trunks also reduce wind currents somewhat, so there is less snow buildup to begin with.

Courtesy : The Hindu

Why do we see rainbow colours on a CD?

Display of colours by a CD can be understood in terms of the working of a plane optical reflection grating. It is a flat optical device whose surface is ruled (striped) with a set of closely and uniformly spaced lines, such that light is reflected by the gaps and absorbed by the lines. , When light falls on a plane reflection grating, it is scattered in all directions by each of its reflecting stripes. These waves from individual gaps are termed wavelets. When we look at the grating from a distance, wavelets from different stripes travel different distances to reach the retina of our eye. Their crests (or troughs) do not reach a given point at the same time. Usually crests of some wavelets and troughs of others reach a point. Troughs have the property of partially or totally nullifying crests and vice versa, depending on their strengths. In this case the wavelets are said to interfere destructively.

But for certain orientations of the grating, it so happens that troughs (or crests) of all wavelets reach a point together, enhancing the effect of each other. The wavelets are then said to interfere constructively. Ordinarily, when light falls on a grating, wavelets corresponding to all wavelengths (or colours) are sent out by the reflecting gaps. Since the conditions of constructive interference hold good only for some particular wavelength, light intensity at the receiving point is exceptionally high only for that wavelength. Light from the grating from the related direction is thus rich in the corresponding colour. Similarly light from slightly different direction is rich in another colour. A CD has a data recording track, which spirals from its outer periphery to the inner circular boundary. This takes many tens of thousand rounds about the CD's centre. When examined along a radius of the CD, it is found to have a structure similar to that of a reflection grating — a set of almost straight tracks running perpendicular to the radius and separated by gaps. Therefore, like a grating the CD also displays colours. Courtesy : The Hindu