Whether it is curly, straight, coily, or wavy, hair is an important part of the human body. It serves to protect the body from physical harm, to give an offensive and defensive sense of touch, and to help regulate the body’s temperature. Depending on where it grows, it may be colored or trimmed, or it may be plucked, shaved, or waxed. In some cultures, the act of cutting and/or styling hair is considered a sign of wealth and status.
Hair is composed of a tough protein called keratin. Its structure is a three-layered cylinder that extends over the skin. The innermost layer is made of amino acids and sugars, while the cortex contains melanocytes, which produce melanin pigment.
The cuticle is a flat, square cell that surrounds the medulla. Its functions include blocking water and chemical insults, and facilitating the removal of dirt from the follicle. The cuticle is covered by a single molecular layer of lipids, giving the hair shine.
The sebaceous gland is located at the base of the follicle and is the site of the production of oil and lipid-rich sebum. It is sometimes called the oil gland. The sebaceous gland produces oil and moisturizes the scalp. It is also responsible for producing lipid-rich sebum that protects the hair and scalp. The sebaceous glands on the head pump out too much oil during puberty. This can lead to acne.
The hair on the human body is constantly growing and replacing lost hair. The rate of growth is dependent on the nutritional needs of the individual, the location of the hair, and the age of the individual. A mature follicle goes through four phases: anagen, catagen, telogen, and resting. The length of the phases and the number of shedding cycles are affected by age, the nutritional state of the individual, and the presence of endocrine and vascular stimuli.
During anagen, the follicle goes through mitotic activity in the secondary epithelium. The process starts with the formation of a bulb that forms the base of the follicle. In the resting phase, the follicle will gradually separate from the papilla, allowing the follicle to be seen. The follicle then expands to a round ball, surrounded by nerve fibers. The follicle then attaches itself to a tiny muscle, called the arrector pili, which forms a heat-trapping layer above the epidermis.
The hair on the head helps to keep the skull warm and cool. It also provides protection against ultraviolet radiation. In addition, it is used to camouflage the bear when it hunts. Several species of mammals, including hedgehogs, have modified hairs.
The follicle produces hair that is thick, long, and pigmented. The hair in the head, however, provides little cushioning for the skull. This is one of the reasons that wearing a hat is still a necessity for some outdoor activities in cold weather.
The most common interest in hair is about the way it grows. It is important to learn about the anatomy of the hair to help treat hair disorders. It is also important to eat a healthy diet and to take good care of your scalp.