Have you noticed that when someone is nervous, he bites his nails or that a person looks down when he feels sad? Well, even though these people are not saying anything, their bodies are telling us how they feel. This type of communication in which our body movements, gestures and facial expressions reveal our feelings and personality is called body language.
Body language is a form of soundless communication, or silent speech. Animals cannot speak, so they depend a lot on body language. An arch its back, while a happy dog will wag its tail.
Human beings ‘speak’ three times more through their body language than through actual speech. Some forms of body language are the same throughout the world. Others change from place to place. In fact gestures that are considered to be polite in one country may be thought to be very rude in another!
Da Vinci code
The artist and scientist Leonardo Da Vinci made thousands of drawings and observations in his notebooks, but his notes appear to be made in a secret code. Leonardo was left handed and his writing goes from right to left. It can be read properly if held up in front of a mirror!
Body temperature can be measured by placing the thermometer under the tongue, in the armpits or in the rectum. The basic idea is to place the heat sensitive bulb of the thermometer in close contact with that part of the body which is not exposed as that may lower the reading. It is also desirable that the thermometer be enclosed on all sides by the body part. The armpits are easily accessible and the fear of broken thermometers is also less. So this is the preferred site for measuring temperature in children. For adults, the underside of the tongue is preferred, as the skin is very delicate here, heat conduction is better and the thermometer reading is more accurate.
When one is hit, the force of impact damages the capillaries or the small blood vessels under the skin although the skin may remain unbroken. When a capillary breaks under the skin, blood oozes out and this internal bleeding gives skin its dark colour. Immediately after the injury the colour is red because of the presence of red blood cells. Gradually these cells dry and start losing oxygen and give the bruise a bluish colour. The thickness of the skin also distorts colour. A bruise may change from reddish blue to greenish blue and then yellow before fading completely.
Wounds on the tongue heal fast because the tongue has a rich supply of blood vessels. This helps the which blood cells to easily reach the site of wound to fight any infection by bacteria and other microorganisms which can delay healing. The saliva too helps in healing as it bathes the tongue in a chemical Iysozyme that kills bacteria. Besides, the cells of upper layer of the tongue divide very rapidly and so the wound in the tongue heals fast.
Usually a person’s fingerprints do not change during the lifetime. Minor and superficial cuts that he’ll do not affect the pattern formed by the ridges that cover the skin of the fingertips. Ridges are the impressions which make fingerprints. However, extensive or deep wounds, severe burns, surgery or disease may destroy these ridges and lead to a change in fingerprint patterns. Deep wounds damage the underlying dermis of the skin and healing often leads to scar formation. Since scar tissue does not show secondary modifications such as hair, it does not show the ridge pattern either. However, these are extremely unlikely events and usually fingerprints are for life.
When you meet another person, or are introduced to him, it is polite to say ‘Namaste’ with folded hands, or extend your hand for a handshake. The handshake is the universal form of greeting in the West. However, even this simple gesture varies from country to country.
Pain is felt only when a nerve end is stimulated by a cut or injury. 
Transplanted organs are rejected because of the presence of special protein molecules present in the body of every individual. Called antibodies, these molecules can easily recognize a foreign body by a substance called antigens produced by the later.
The stomach is a muscular bag-like organ that digests food with strong acids contained in gastric juices produced by glands in the stomach lining. To protect itself from being digested along with the food, the stomach lining is coated with a thick layer of mucous produced by mucous cells. This mildly alkaline mucous secretion protects the stomach against the acidic digestive juices.