Hair is a part of the human body that serves a variety of functions. It protects the skull from the sun, provides insulation from dust and other elements, and extends the human sense of touch beyond the skin. It is also important for many animals, including polar bears, to regulate body temperature. Polar bears, for example, have black skin, but their transparent fur gives them a white appearance. They also use hair for camouflage during hunting, and to conceal their cubs in snow.
Hair is made up of 95% keratin, a protein that is helicoidal and insoluble in water. This makes it extremely resistant to moisture, ensuring its impermeability. It contains 18 amino acids, including cysteine, which forms disulfide bonds between molecules and gives hair its rigidity. The hair structure is shaped like a series of scales, each measuring approximately sixty micrometers in length and six micrometers in width.
The porosity of the hair is an important factor to consider when choosing a style. It can help determine the best styling product for your hair. It also plays an important role in determining how long you’ll need to style it. The higher your hair’s porosity, the longer it will take you to style it.
The origins of hair are not completely understood, but scientists suspect that it originated in the common ancestor of mammals, called synapsids. Although there are few fossils of synapsids, there is evidence that the stock of these animals had a hairy head, a feature similar to that of modern crocodiles. Therefore, hair acquisition in the synapsids cannot have occurred earlier than 299 million years ago.
The follicle in the scalp contains cells that help the body heal when it suffers from a wound. These cells can move quickly to the site of the wound and help the white blood cells in the immune system. These cells can also be found in hair follicles, where hair grows and provides nutrients and blood supply.
Hairstyles have become an integral part of many subcultures. Hippies, metalheads, and Indian sadhus often sport long hair. Punks often sport spiked or mohawked hairstyles, while skinheads have hair that is either completely shaved or short-cropped. In the 1920s, bobbed hair became popular among female art students and flappers.
The health of the scalp is vital to any hairstyle. Hair care products should be applied to the scalp after shampooing. This will help prevent product buildup. If your scalp is oily, products will be harder to absorb. A healthy diet will help keep the scalp in a good condition and prevent hair damage. While it may seem trivial, it is essential to look after your hair in order to keep it healthy.
Hair growth occurs in phases. During the anagen phase, hair roots grow and develop melanin. At the end of this phase, hair is pushed out of the skin and begins the transition into the next phase, called the telogen phase. The telogen phase lasts three to four months. This final resting phase is crucial for the health of hair.